A little advice on checking the valves for leaks: DON'T use water. I've seen so many people do this thinking that because water doesn't drip out the intake or exhaust, that there's no leaks. The reason you don't use water is because you're putting water on previously oil coated surfaces that are polished, which makes them slightly hydrophobic. With the surface tension that water has on that hydrophobic surface, it can float above small gaps and not bleed through. Instead, use a solvent like acetone, xylene, or even gasoline. They have lower surface tension, and will actively leech through any gaps or leaks in the valves. Hope this helps.
@@austinrobinson186 are you trying to get cancer? Cuz that stuff is super carcinogenic! That's why they banned us using it when I was in the navy, aside from the fact that it causes hydrogen embrittlement on some metal(makes it weaker)
Man! This is GREAT! I'm a 42 year old automotive master technician and I had NO IDEA they made sooo many parts for small engines! You just opened a whole new world up to me! Coolest thing I've seen in years!
Alright, I don't have interest in go karting,, and I haven't messed with engine building for almost 20 years, but I watched this entire video because I follow your interests that you share via videos and the podcast. You have gained so much knowledge from when you started this hobby, which is really awesome to see. Your knowledge and passion is clear in this video. Kudos, and keep it up!
This is one of the best engine build videos I've ever watched. If a person can quickly and simply explain a complicated subject then they actually know what they're talking about. 10/10
When i raced box stock i took new head gaskets to a shop with a 300 ton press. I made 2 steel plates 2" thick , put the gaskets between them and reduced them to the minimum allowed thickness. It helped get that fraction of compression other builders didnt have. Every tiny bit helps as you know. Great video!
Why didn't you simply buy a thinner gasket? Aftermarket gaskets have been around for decades. Smashing them in a press is the most ridiculous thing I've ever heard of. The size of the gasket IS going to expand IF you succeed in getting it ANY thinner. Now it will be hanging inside the bore. NO good. Edit: ALSO, with a flathead engine like these were years ago, reducing the head clearance ALSO reduced your "port flow" as it reduced the clearance between the area between the valve and the surface of the head where the air flows. It is NOT an automatic increase in power with these engines by increasing the compression. There is a VERY fine balance between raising compression and then negating any increase in power because of the reduction of the airflow passage of BOTH the intake AND exhaust area between the valve and the head. The more you lower the head to increase the compression, the more the intake and exhaust airflow has to take a sharper turn to make it in and out of the valve AND the total area of the air passages ends up reduced also. It ISN'T as simple as "shave the head" or "run a thinner head gasket" in those engines and end up with more power.
I started racing when I was 15 sprint kart racing (short course asphalt). It was a great place to learn to drive. Then I got into road racing karts. It was huge in the 80s. Every Christmas our family would race at Daytona. The smallest class I would run still had 50 or 60 karts. Some classes (usually Yamaha) had over 100 entries. It was the most fun times I had with my dad, not just the racing but the hours of preparation we spent in the shop and the travel to the races. It was all good, and I learned so much. It was a great way to grow up. Thanks for bring back the memories, even though we ran two strokes 😜. Be safe and have fun 👍
I was an engineering technician at Briggs & Stratton and worked on kart engines as well as the dragster engines. Fascinating, I never realized the fanatical customer base for these engines.
When you start with a out of the box engine and then drain it before starting your work on it - it is easier to stay clean. Run a few laps on dirt and then start the process and it will be a different story.
Watching from the perspective of someone who grew up on an automotive machine shop, looks like you did a great job. You can build a flow bench and actually play with porting a lot more. There is even a way to smoke it and actually see the flow characteristics and what a subtle change can do.
The best way to check for proper valve sealing is with a vacuum pump. It’s easy to make a plastic plate (add a quick disconnect to the plate) that bolts to the head and use a MityVac vacuum/pressure tester and you’re good to go.
I’ve watched dozens and dozens of videos on small engine building for mini bikes, and none of them teach better than this guy. Awesome video and explanation!
Pretty cool! I built Hi-Po 'Lawnmower' engines in the 70s. Back then, the trick was to use Tecumseh engines (Forced Oiling) and we even converted some from vertical to horizontal flow, shaved the heck outta the heads and changed the oiling pickup. Ignition timing was adjustable on those engines as well. We used 5 HP camshafts in 3.5 HP engines and used two McCulloch chainsaw carbs on an Aluminum manifold. We started these engines on Gasoline then once warmed up, they were run on Methanol-Acetone mixture. Pretty heady stuff for a 15-year-old with a very smart Power Technology teacher and a small dynamometer.
One of the best comprehensive videos on RUclips. You sir have your act together... I am a retired mechanic that will venture into this world of the predator realm with this knowledge. Thx
That brought back memories of my younger days messing around with cars. I did the heads on a 1990 Thunderbird I bought for $500 while I had it parked on a jobsite I was working at 20 years ago, and that was the last time I did any serious engine work. Now I'm thinking gas powered table saw... :) Awesome video, David!
Delta’s “The Modern Motor Driven Workshop” published in 1930 shows how to hook a gas engine to their table saw of the day. They even go so far as to show how to rout the exhaust pipe out the wall of the workshop.
Racers today do not know how lucky they are having videos like this. When I started in the 80s, racers would tell you a little & the rest was bullcrap. You had to get pieces from different racers and put them together to get the whole picture.
When I started in the mid-90's, the guys you were competing against would outright lie to you. The guys you may be competing against in the future would tell you half truths and everyone else would just ignore you. If you wanted to compete, you either needed to find someone that had stopped racing and was just there to "hang out" or find an engine builder that had drivers in other classes.
@@aaronthomas6155 or do engineering. Usually this kind of knowledge you have to pay for.. but with internet being what it is today engineering can be done in your garage with a few videos. I took aerospace manufacturing and aviation maintenance, so I understand the principles that make an engine pur exactly how you need it
@@letitbe90210 I've raced against mechanical engineers. They were great at building engines but were horrible at setup and reading a track or weather. Not everything can be learned on the internet. Somethings only come from experience.
Idk how yt brought me here, but as a mechanic that worked in a bikeshop and tuned engines myself, I was very pleased to watch this. You explain things very well for starters with no needed fluff or editing. Great stuff! Hope you have a great day good sir.
Man, this is presented so well whether for a beginner or even someone like me who knows a ton about many engine types and is just getting into these. I wanted to know the reason why youre replacing certain parts for THIS engine so that was great!
Wow, great video ! I raced a McCulloch 101AA long ago. I think it was turning about 9k rpm on nitro 9 and variants. Of course, that was old technology that has been long surpassed. I never completely re-built one, so watching this was interesting. Even back then, it was amazing just how much science went into better performance. From frame flex, carbs, clutches, carb air flow "shapers", exhaust, tire compounds and on... So I can just imagine what's out there now, compared to then. Thanks for sharing !
As a machinist at a shop, what I recommend during the water leak test, actually fill the port and blow air against the closed valve. If you have air bubbles, gotta fix the seats 👍 Good video and interested in watching my work but on a smaller motor
If you're cutting valves after your lapping you can use blue daikum and it will show your high and low spots if you have any if not it will be a complete circle around your valve and you can see a good seat
My wife wants to get back into gokart racing, she would've been doing races and shit when she was a kid but her dad started making excuses to take her. I'm getting it soon to rebuild and get her back into it. Definitely saving this video, you did an amazing job describing everything and explaining exactly why you make the modifications and their purpose for you. 10\10 my guy!
My dad always did the exact same thing. I would ride my go kart all day everyday when I wasnt in school. My dad would get my hopes up by mentioning go kart racing and I'd think that maybe he was gonna take me and let me do it but anytime I'd ask he would have some excuse why we couldn't. He never failed to have an excuse why we couldn't do something. I caught myself not long ago doing the exact same thing with my daughters and it made me feel bad. I have to learn to find excuses to do more things with them
@@Wreckz_TeaHey, my father did the same kind of thing with/to me, regarding making excuses. When my son was born, I swore to myself and my wife, that I was not going to do that to him. I had a good father, don't get me wrong. But when you tell someone that you are going to do something with them, and then the time comes and you make an excuse, it really messes with their mind. It always made me feel like I wasn't important enough, and gave me poor self esteem. Anyways, when I told my son we were going to do something, I made a point to do exactly what I had said.(But be careful what you say, because day to day life is hard to predict anymore) But I feel like my son grew up with a complete 180 degree view on his self esteem as compared to how I grew up. I am so proud of him and the father that he is, now. Also, he didn't go through all of the drug and alcohol dependency that I did, because of his self esteem compared to mine. Children's minds are very moldable, so don't make excuses for things that you said you were going to do. If you don't intend on following through, don't even bring it up. Just my 2 cents. Sorry for rambling.
Man I have never been into kart racing but I have to say I thoroughly enjoyed this video. From the detailed explanations to your fantastic cinematography and production. Absolutely amazing job with this video. 👏
best thing I have seen this year, when I was 8 I had a 2.5 hp mini bike my grandfather did what your doing .... it changed everything . now I ride an nitrous R1,
When i first came across this video and had little to no experience with building or modifying these (or any) engines, I never got past the first couple of minutes. Now that I have modified several engines and I'm always swapping or grinding something to pull that little bit extra power out of them, this video is way easier to keep up with. I like the fast pace you've managed while being as thorough as this video is. One of the best clone building videos on RUclips, and Im confident because I think I've seen most of them. Great job.
Some very useful information here ....glad to see someone working with what they have and not using extremely expensive machining equipment. To me this shows you can do it with basic garage tools along with a few specialty hand tools. Thanks for a very detailed video.
I used to be into yard carts in my early teens but haven't had any opportunities to play with them since. I watched this entire video from start to finish--man, what a great little intro to engine building! I've been a sub of Cars&Cameras for years, and have seen some of the stuff you've done on their channel, plus a bunch more from you now. Thanks for that. Really enjoyed this. Cheers~
Some of us don’t have friends….😂 I don’t have a kart but want one…recently started seeing these harbor freight engines popping up in my feed…the WANT is high! So much to learn!
When checking the valve seals you should use petrol or diesel, water is way too thick to test an air seal. Petrol will evaporate if left for too long so keep an eye on it
@@davelowets There's a correct way to do a lot of things, if petrol isn't leaking through however the compression is good. No one is buying a tool for a one time job, i certainly ain't
The zinc additive was removed from engine oil by the EPA in 2013. It's essential for any flat tappet or non roller lifter valvetrain. I'd use it past the break in.
grew up with guys like this teaching me in the early 90s. its refreshing to see what i learnt way back when still be very effective today good work man.
Came to this video by chance - was so full of knowledge and reminds me of 2 things - 1. A lot goes into these things, but 2. If one is willing to learn and put in the time, one can do this. Highly appreciated!
I have two karts and have always built my own engines and with the information from Jody and the awesome people at ARC, I've been very successful. And in my opinion your video is very good you hit all the bases without having to hear yourself talk like some do. Kudos to you, keep up the good work!
David, that was brilliant. You are an excellent teacher. I've watched tons of "engine" videos but this made it simple for me because there's only one piston to worry about. Thank you very much for that. New subscriber.
Wow...Just a high school and college kid when I "built" a Ford 289 for my 65 Mustang and a Honda 450 DOHC motorcycle engine. Fiddled around with porting and polishing with a piece of plexiglass and a graduated cylinder from chemistry class. Your video is so detailed, practical, and precise I was remembering my youth and my uncle "MC" who was a master mechanic from a young age. Sure read a lot of "Hotrod Magazine" back then. I do remember a speedy "racer" gocart with a McCulloch 2 cycle engine that we rode around the neighborhood as kids. It made so much noise we got an unpopular reputation in some areas. GREAT VIDEO !!
Do it on your rider.... it'll go faster, you'll get your lawn done quicker, and you're sitting on top of the blade, no getting ankled like you would walking behind your push mower, if the blade decides to go for a cruise.... 😬
Those HF engines are no joke. I've been seeing them used in a lot of places, especially over similar Hondas. similar power and reliability for fraction of the cost. It's pretty cool. I'm debating picking up a Predator engine (non-ghost) for my kids' yard kart just to replace the finicky one that's already on it.
@@brodieodell1974 I have to fix the steering before I worry about the engine. My oldest sent himself to the emergency room when he ran head long into a tree with it. No point in making it go if you can't tell it which direction to go.
Circlip tip (7:30): make sure the opening is facing up or down, relative the stroke. If the opening is to the side, at high RPM the G forces can compress the clip enough that it can come out. Overall an excellent video! I don't even race carts and this makes me want to build one. :) How do these things hold up with splash lubrication?
Easily the best video building out a small engine ive seen and ive seen many you explained everything that you talked about explaining how and why you are doing this modification, well done
A tip I picked up from somebody that rebuilds motorcycle engines is to build yourself a small open square of wood out of two by fours or maybe four by fours and the engine case will sit on top and inside the square and not move around so freely on a flat bench. It’s sort of hard to explain but in essence it’s just an open square of wood that’s tall enough to allow the engine case to sit proud of the bench top. It’s so simple when you actually see it but I never thought of it myself. It really keeps the case from sliding around on the bench.
The Ball hone achieves something akin to a sandpaper finish, the long chain hydrocarbons in the oil that offer lubricity between piston and bore get sheared quicker and the oil fails sooner affecting the rest of the bearing surfaces. Buy two of those 3 arm sprung hones, one with course stone and one with fine stone and build the hone finish properly. Piston rings are designed to hydroplane along the cylinder wall on the oil caught in the "deep" hone. The initial overlayed shallow hone atop the deep hone is meant to abrade the rings to a mating surface H7 fit. The light hone is at the same time abraded away to form plateaus atop the deep hone peaks, this is the breaking in process (breaking off the minor peaks). The deep hone valleys anchor the splashed oil till the rings shear through this oil then, hydro glide across the plateaus. That said the ball hone is a mongrel tool that doesn't deliver the engineered principles desired. Yes ball hones seem to work but not like the proper hone finish. When you're chasing performance (HP & longevity) for 7000rpm average make a torque plate and bolt it down to simulate the head, this will twist and bulge the barrel, the course honing will return the bore to cylindrical, reduce piston flutter and oil shear so more power. Apply the course hone with faster reciprocating action for a more acute (60/30) hatching in line with the bore to allow for easier oil shedding, the light hone can stay at 45. Coning the bore off perfect cylindrical 2-3 tenths larger at the bottom for reduced friction adds HP and longevity as the effective pressure is so much lower at the bottom and doesn't need rings shearing the oil to form as great a seal. The piston could do with an oil hole drilled through each wrist pin boss for better friction management so more power. The piston skirts narrowed give better engine acceleration and lower peak impulse load on the bearings, the piston skirts aren't cylindrical and examining an old piston will show the "contact" patch you can machine a new piston skirt upto. Finally turning the piston around will give you slightly more compression but more slap and wear, it's a geometry thing. You skipped over performance valve and seat prepping, guess that's where you've keeping true to promise.
First, love the video! First time I've seen any engine builder go through step by step of what is necessary for a competitive motor.... for any kind of racing. I can say that in the car engine world the rings vs. bore finish have come a long way. Very thin rings vs. finely finished bores etc. The ball hone gives you the cross-hatch pattern which helps leave some oil on the walls. Then there is ring gap.... It used to be the bottom ring (3 ring package) was gaped smaller than the top. But apparently that leads to flutter on the top ring. Of course you want to go with the lightest piston (reciprocating mass sucks for power). Roller bearings on the cam.
@@confuse9 What's come along way is thermal management. What's changed is the compromise delta. As bores maintain cylindricity over the wider thermal range, manufacturers have reduced compensatory design (clearances for thermal change, ring pressure, film viscosity). Shorter chain oils, and lower spring pressures means lower drag so better (fuel tank) economy. This requires a very accurate ring on oil to bore calculation. Throwing a ball hone in modern, low ring pressure, engines cant achieve plateau requirements as it cant in older engines either. Look at Audi over the last 15 years and you'll find increased oil consumption rates as they chased the low internal friction delta. Audi's bore finish breaks in almost immediately and has the right ratio of scratches (valleys) per area for oil retention but not (**see service manuals and law suits) over retention. Best use for a ball hone is to remove grease and rust from a block prior to proper machining. Aging a block in the back yard or grabbing a high mileage block from the breakers is valid but really harsh on workshop machine tools. Emery taping the deck faces and ball honing the cylinders saves expensive carbide inserts from cutting abrasive oxides, that's a good use for a ball hone, as a heavy duty cleaning brush.
I agree with you 100%. The cost and time to hone the cylinder correctly will add longevity and keep more HP longer. Definitely worth buying a set if you are going to build more than one engine.
I will 100% watch every video like this you make. I love the mechanical workings and visibility of all the gears. Not to mention I love tearing down and rebuilding small engines like these.
Great video David! I'm a FAA A & P, , and I'd like to share nothing happens without "ignition". I hope you'll find the aviation version of the internal combustion cycle to be more accurate. Which is: 1) Suck, 2) Squeeze, 3) IGNITION, 4) Bang, 5) Blow. Great tech video, , you point out ALOT of very good tech points and assembly processes for high output engines! Lastly, you have really good production (sound, lighting, layout and editing) values. Loved it!
@@genefogarty5395 Gene, yes they do. Please reference any aircraft mfgr's piston or gas turbine engine operation discriprion. You are misinformed or do not know the facts with gas turbine or high bypass gas turbines. These are commonly called "jet" engines. . I'd recommend reviewing the Continental IO540, a 540 cubic Inch "Opposed Piston" with ovhd vales. Or the Pratt &Whitney 4000 GTF (Geared Turbine Fan). A typical jet engine has multiple rows of compressor blade. Then multiple rows of blades in the "hot" section. The air enters a typical gas turbine and is very highly compressed. In some engines it's compressed from static atmosphere pressure of 14psi (sea level) to >200psi. in the "Compressor" section. This very compressed air flows into the hot section. Kerosene is injected at very high pressure and inside this "hot section are "IGNITORS". There are two types of ignitor systems. The continuously "sparking" ignitor or the continuously "Hot". These "ignitor's" are needed to ensure that the kerosene gets ignited in a very high pressure and very, very turbulent gas flow! This flame front then expands the pressure in the "hot" section by 5X or more! This pressure then expands as it flows across/through compressed hot section blades, creating a massive pressures and force. This gas the exits the jet engine via a third set of compressor blades called the "Re-Heat" stage. So, in a nut shell, it's Suck, Squeeze, IGNITIO, Bang, Blow! I hope you have benefited from today's class. All the best, TAC
@@WestKyCrime This was a 4 stroke ICE, not a jet, dude. It's still intake, compression, ignition or bang as you call it and exhaust. Ignition and bang are one and the same. There's no delay, it's an explosion. But thanks for the "Class"
@@genefogarty5395 sure, we all have our opinions. Let's walk thru what happens in a ICE ignition event. And I'll try to see if I can convince you why Ignition is its own "event" in the ICE operating process. The crankshaft magnet on the flywheel (engine in the video) passes by the stepup voltage transformer. The magneto (AKA a very strong magnet). The step up voltage coil then excites the main voltage step up transformer (AKA as a "coil pack"). Once the voltage exceeds the ignition systems regulator (AKA as a special type of capacitor), this high voltage then seeks a path to ground. And "wah-La", it's ignition time. Bang occurs AFTER this above ignition event. In closing, I bet you will agree, that the first thing experienced technicians ask when trouble shooting a ICE is, "Is it getting Spark"?. Next question is likely "is it getting "Fuel"? So, I hope you can now agree that "Ignition" is its own event in Petrol ICEs. All the best Gene.
@@WestKyCrime It's a 4 stroke. If there's no intake air coming in it won't start, no compression, no start, no spark, no start, no exhaust going out, no start. Pretty simple.
I think i learn more from youtube than i could in college. One day I'm learning how to change belts in a tape deck, the next day how to build furniture, then the next day how to re-build a go kart engine. I didn't even seek this out, it just got recommended to me like everything else. But, now I know how to do it.
Thank you David for putting this video out. I have been curious about the process and this will be a GREAT resource in the future for lots of people. You first teased this on the podcast and it had me intrigued, great information throughout the video. 👍🏻👍🏻👊🏻👊🏻
Commonly I see isopropyl alcohol used for checking the valve seal before the first heat cycle, but always remember that if you have teeny tiny itty bitty leak, the chances of it sealing after running for a break in are almost 100%
This just popped up on my feed, and it's such a well done and organized video, you can litterally feel the amount of effort put in as you watch it. I decided to subscribe and go through your channel and you litterally do everything, which is so cool to me. Will be watching many more videos from you.
I don't even have a kit car, but there is a kit car track track in my small city where I live. It's 2:00am after getting off work watching how to build a built engine for a serious go kart track. Well done sir!
I will never build my own engine/cart. I will probably never use this knowledge in practice but it was nice 43min with you and even as I'm non native speaker I had no issue to follow what are you doing and why. Great job. Thanks to people like you, the internet is better
@@dondelchulia3189 the Predator is gaining traction FAST so it depends on the region and if its "box stock & sealed" rules or not...you can build a BADASS predator for about $650 all in that a box stock $600 Lo206(Undressed at that) cant even compete with. And that can be upgraded even further without much more than a cam/spring swap. Around here, almost all Kart classes allow predator based engine....even some predator based Jr. Dragster classes are common at the strips around here now
7:43 With a Trabant engine the entire cylinder is a piston ring compressor, it's tapered and installs after the piston to the block. Off topic but just realised how neat it is
Awesome! I learned more about engine building, building any engine, than I've learned by osmosis in all my years of working with gasoline engines. Excellent material. A Master-Class in engine building.
Just a question: by changing the connecting rod and piston, as well as removing material from the crankshaft, wouldn't the crankshaft require rebalancing to accommodate the changes especially since it will now be turning at 8,000 rpm?
You have to remember that these motors are a single piston motor not a traditional motor with 8 cylinders that spin the crank at once. So take the side cover off of a motor and turn the motor over. There is only one point where the motor is perfectly balanced and that is when the crank is completely in line with the rod and piston. The other 99% of the time the crank and counter weights are not going to be in that position. I hope that was easy to picture in your mind. But to answer your question plainly no you never have to balance a crankshaft in a single piston motor. The only thing that you really should do is make sure the bore is true.
@@SomethingAboutMaking Another tip that people don't really let out is call JC Specialty up and order hardened side cover bolts this keeps the side of that block from flexing with those oem bolts. I know it probably sounds silly but it adds a substantial amount of strength to a predator block. Considering that predators are the weakest blocks of all the clones this is a must for every one I build.
@@JakeSeiner well excuse my ignorance. Just assumed swapping out stock heavier con rod and piston for lighter components would require balancing, especially taking an engine meant to rotate at lower rpm's and pushing it out to 8k. But I have never souped up a lawnmower enigine.
Too bad you dont have a way to dyno before and after. I'd be interested to see the difference it makes. Also, can you please explain why tf you have a background that makes it look like you're rebuilding go kart engines in a preschool? It really makes me feel uneasy about this whole thing
Wait, so you can't install a separate stroked crankshaft because that's against the rules, but lengthening and increasing the compression is totally acceptable? That makes literally no sense 😂
Ya, my friend did this kinda stuff carting as a kid. 40yr old MF'er still proudly displays his trophies. You're all frigging cheaters who, like Tom Brady (who I like for a lot of other reasons) must win at ALL COSTS. What cost is it when I think you're a frigging idiot cheater? If you do this with children, you are seriously mentally deficient and need your head examined.
To check valve seal I always used brake clean (thinner than water) and used a air gun and a rag to "seal" and look for bubbles. Not sure how correct this is but I've identified leaky valves this way
Is that drill Festool? Looks like it but doesn't sound like it. I've been using mine daily for almost 15 years. Incredible quality. Thanks for an interesting production.👍
The most concise and detailed video on RUclips for building a Predator engine. Thank you for taking the time to explain the steps that go into the art of building a race engine. You have a natural talent for teaching. I am a new subscriber, and thanks again for the information.
I don't have a go-kart but love to play with engines this video was so complete i watched it from a to z.Thank you for taking the time to make this video. Even a noob can have a good idea of how a gasoline engine works.
Respect for diving into a subject, parsing the info, and presenting it in an easy to understand medium. ::side note:: I bought a dirt bike when I was 15, disassembled it to repair, and never got it back together! 🤣
65+ years of studying engines and you did a credible job of explaining the rationale for modification in less than an hour. Great job! Definitely can’t afford to do what you have, but the bug is still there. An additional note - 1.3 million views, 50K subscription, 21K likes. …? As if it costs a second to acknowledge that you did a ton of work using a thousand plus in “props” doesn’t seem credible. I had to scour library’s, spend limited income, and thousands of hours of research and today it’s difficult to actually click on the thumbs up icon. Huh
Excellent video, easy to understand everything. As an old kart racer back in the early 80's you brought back some great memories. Now i just rebuild Vittorazi Atom 80cc to stock.
That was a great ending building video. I used to build those engines for a friend who raced. I did not know all those cylinder head tricks except for stiffer springs and milling the head. I started safety wiring the side cover bolts cause of a failure where they loosened and ithe engine blew up. He had the same header as you, I wrapped that with DEI header wrap to prevent burns. I made a tool for holding the crank to the block for torquing the flywheel nut. For removing the stock flywheel I drilled and tapped the stock flywheel 3/8 nc and used a steering wheel puller to remove it. The same steering wheel puller with different studs would remove the ARC racing flywheel.
I am not used to seeing people working on these types of engines as go-karts. In Australia we mostly see the smaller and much much faster 2 stroke engines in our professional go-karts. If it cant reach a minimum speed of 100kph / 60mph then it is considered a toy for small children. Your work in stripping and then altering and hotting up the engine is well done and amazing to watch. Well done! :) It isn't uncommon to spend $6000 to $10,000 on professionally built 2 stroke Go-kart engines. Good friend always told me it was cheaper racing Formula Ford that it was racing in the Go-Kart State and Country wide Nationals.
I do Most of this when I build stroker scooter engines and alot more little secrets. I'm old-school kart builder but we only had flathead engines back then, but we went over and beyond of what people thought was impossible back then alot of secrets Lol. This is a very informative/awesome video for anyone that needs a little more kick on their mini bikes or karts.
Mate I’m a heavy duty mechanic by trade and build manuals and do maintenance consulting. There is companies that would pay to have you do their rebuild and educational videos. You’re concise, well informed and the presentation is easy to follow. Seriously something to look into.
I've never raced carts and likely never will. However, this video was a super fun watch. I like engined and tinkering with things. So, thank you for the informative and interesting video!
sir i am NOT engine savy but as im watching ur vid, it makes me wanna go build my own go kart. the vid was very detailed and easy to understand.. also very enjoyable to watch.
Really love the explaining everything in detail. Someone like me has general knowledge, but has never taken part of motor feel after watching your video could tackle a job like this 😎
Man your awesome I have been looking 3 years for videos like this I enjoy restoring and creating modified go kart people throw away, I bring back to life
New sub....anyone that explains a process so well and clear with no fluff means they completely understand what they saying great work good video thanks
You know what? You do an excellent job in every aspect of a how to video. Probably why you have success in the other hobbies you do. I wish you luck in your races!
i like that your going through all this. back in the early 2000's i used to race a class that was based on the briggs animal 6.5hp. It was an open class, the only requirement was that we had to use the briggs block, everything else was fair game. At one point we had a dome piston, roller rockers, custom cam, and even had machined the head to accept valves from a honda civic along with many other things done to the head. made almost 50hp. raced on a short flat dirt track, if you can imagine we ran a 11thooth on the clutch and 68-70tooth sprocket. I would say our most reliable versions of the engine had flat top pistons and briggs valves with mainly a worked head and custom cam making about 30-35hp. Our big engine does hold the lap record though.
Nice job. The details were great but the racing video at the end is the perfect finale. Looks like a real blast racing those small karts in such a tight little track.
Damn bro, you definately earned that thumbs up! From idea to running bike is brain shaking. And how smooth it runs! All yours bro. Amazing! One of the most ambitious projects I’ve seen pulled off on RUclips.
I raced in IKF 4-cycle Stock Heavy and Super Stock classes on dirt tracks in the Midwest for 15 years. I was also one of our local club's technical inspectors. This was back when IKF ran the 5 h.p. Briggs horizontal shaft engine. We ran on 100% methanol. We always clearanced our engines which reduces friction and increases hp substantially. We would always run a worn out top oil scraper ring to reduce friction. IKF 4-cycle engine technical rules didn't allow the oil ring to be completely removed. It just had to have one. Since oil consumption isn't a concern we just ran a worn out one. The IKF Stock light, medium, and heavy classes had to run the stock Briggs carburetor. We ran Tillotson carburetors with billet aluminum intake manifolds in the super stock class. I actually ran Klotz KL-200 fully synthetic 2-cycle oil in all my engines. I had absolutely no carbon buildup whatsoever. Since Klotz didn't specify the SAE weight for their KL-200 oil at the time I measured it myself. I was a mechanical engineering graduate student at the time and was performing SAE viscosity testing on biodiesel fuels at the time. I measured the Klotz KL-200 fully synthetic oil to be in the range of an SAE 50 oil. The one thing you don't want to do when running on methanol fuel is to leave it in your engine for extended periods of time. That's because methanol is highly hydroscopic and will attack non silicone (red) gaskets and seals. On my superstock kart I had a quick connection in my fuel line running between my belly pan fuel tank and Tillotson HL336 carburetor. It was a quick connection with automatic shutoff valves on both sides. I made a gasoline flush tank from a one gallon plastic gas can with a short fuel line and male quick connection with shutoff valve just like the one connected to my kart's fuel tank. After every race day I would unplug my quick connection on the kart and plug in my flush tank. I would then start the kart on methanol left in the fuel line and carburetor until it was running on gasoline from my flush tank. I had to pump the throttle lever on the carburetor to keep it running on gasoline. I didn't connect the methanol tank to the carburetor until the next race day. By flushing out my carburetor with gasoline in this way, I never had any methanol related problems. Since methanol is highly hydroscopic always keep your methanol fuel sealed up tightly. Otherwise it will absorb moisture from humid air.
A little advice on checking the valves for leaks:
DON'T use water. I've seen so many people do this thinking that because water doesn't drip out the intake or exhaust, that there's no leaks. The reason you don't use water is because you're putting water on previously oil coated surfaces that are polished, which makes them slightly hydrophobic. With the surface tension that water has on that hydrophobic surface, it can float above small gaps and not bleed through. Instead, use a solvent like acetone, xylene, or even gasoline. They have lower surface tension, and will actively leech through any gaps or leaks in the valves. Hope this helps.
Well said
Yep! You need the most oil-eating liquid possible.
@@Kootwoot MEK! lol
Gasoline works very well. Never use water
@@austinrobinson186 are you trying to get cancer? Cuz that stuff is super carcinogenic! That's why they banned us using it when I was in the navy, aside from the fact that it causes hydrogen embrittlement on some metal(makes it weaker)
Man! This is GREAT! I'm a 42 year old automotive master technician and I had NO IDEA they made sooo many parts for small engines! You just opened a whole new world up to me! Coolest thing I've seen in years!
I'm a master technician super mechanic.
YOU SOUND PRETTY BAD AT WHAT YOU DO !
Those predator motors are popular among racers , and mud boaters .
“Master”😂
Master Og way 😂
Alright, I don't have interest in go karting,, and I haven't messed with engine building for almost 20 years, but I watched this entire video because I follow your interests that you share via videos and the podcast. You have gained so much knowledge from when you started this hobby, which is really awesome to see. Your knowledge and passion is clear in this video. Kudos, and keep it up!
Thank you Chris! I always appreciate your kind words!
Guy has info I have not found in other channels
same here! not into small engines but this video is making me reconsider it!
💯 agree!
A
Qws31 God damn all right
This is one of the best engine build videos I've ever watched. If a person can quickly and simply explain a complicated subject then they actually know what they're talking about. 10/10
It’s a toy mate it’s not that hard😂
When i raced box stock i took new head gaskets to a shop with a 300 ton press. I made 2 steel plates 2" thick , put the gaskets between them and reduced them to the minimum allowed thickness. It helped get that fraction of compression other builders didnt have. Every tiny bit helps as you know. Great video!
Why didn't you simply buy a thinner gasket? Aftermarket gaskets have been around for decades. Smashing them in a press is the most ridiculous thing I've ever heard of. The size of the gasket IS going to expand IF you succeed in getting it ANY thinner. Now it will be hanging inside the bore. NO good.
Edit: ALSO, with a flathead engine like these were years ago, reducing the head clearance ALSO reduced your "port flow" as it reduced the clearance between the area between the valve and the surface of the head where the air flows. It is NOT an automatic increase in power with these engines by increasing the compression. There is a VERY fine balance between raising compression and then negating any increase in power because of the reduction of the airflow passage of BOTH the intake AND exhaust area between the valve and the head. The more you lower the head to increase the compression, the more the intake and exhaust airflow has to take a sharper turn to make it in and out of the valve AND the total area of the air passages ends up reduced also. It ISN'T as simple as "shave the head" or "run a thinner head gasket" in those engines and end up with more power.
I started racing when I was 15 sprint kart racing (short course asphalt). It was a great place to learn to drive. Then I got into road racing karts. It was huge in the 80s. Every Christmas our family would race at Daytona. The smallest class I would run still had 50 or 60 karts. Some classes (usually Yamaha) had over 100 entries. It was the most fun times I had with my dad, not just the racing but the hours of preparation we spent in the shop and the travel to the races. It was all good, and I learned so much. It was a great way to grow up.
Thanks for bring back the memories, even though we ran two strokes 😜. Be safe and have fun 👍
im afraid you are now part of the automotive community and you may never stop making automotive content. Congratulations!
Ive been telling people for years to flip these small engines to lubricate them before the first start
Its good to see someone actually doing it
pull it over slowly a few times or pull it over a few times before actually trying to start it. Small engine or big engine - same idea.
When resurfacing a head with the flat glass/sandpaper technique, work the head in a figure 8 motion to avoid uneven material removal.
And a slight concave backing plate to get it flat.
I was an engineering technician at Briggs & Stratton and worked on kart engines as well as the dragster engines. Fascinating, I never realized the fanatical customer base for these engines.
You are the cleanest mechanic I have ever seen. You rock Dave. “Some of us don’t have friends “ You always crack me up with your humor.
When you start with a out of the box engine and then drain it before starting your work on it - it is easier to stay clean. Run a few laps on dirt and then start the process and it will be a different story.
CLEAN... USE OF DREMEL SENDS SHARDS OF METAL AND ALUMINUM IN THE CRANKCASE BEARING..
Hey, I don't have any friends and I don't even have a life. That's why I'm watching Dave's life.
You say humor but it's true😂
@@eddyraye5825truth
Watching from the perspective of someone who grew up on an automotive machine shop, looks like you did a great job. You can build a flow bench and actually play with porting a lot more. There is even a way to smoke it and actually see the flow characteristics and what a subtle change can do.
The best way to check for proper valve sealing is with a vacuum pump. It’s easy to make a plastic plate (add a quick disconnect to the plate) that bolts to the head and use a MityVac vacuum/pressure tester and you’re good to go.
You are correct sir. It's called a leakdown test, and it does work well.
proper for a shop...you can use a solvent if doing yourself at home. guessing this is for the budget racer.
I’ve watched dozens and dozens of videos on small engine building for mini bikes, and none of them teach better than this guy. Awesome video and explanation!
Pretty cool! I built Hi-Po 'Lawnmower' engines in the 70s. Back then, the trick was to use Tecumseh engines (Forced Oiling) and we even converted some from vertical to horizontal flow, shaved the heck outta the heads and changed the oiling pickup. Ignition timing was adjustable on those engines as well. We used 5 HP camshafts in 3.5 HP engines and used two McCulloch chainsaw carbs on an Aluminum manifold. We started these engines on Gasoline then once warmed up, they were run on Methanol-Acetone mixture. Pretty heady stuff for a 15-year-old with a very smart Power Technology teacher and a small dynamometer.
how did you guys make forced oil in these engines you guys make your own oil pump?
@@ephenj Techumseh engines have an oil pump.
One of the best comprehensive videos on RUclips. You sir have your act together...
I am a retired mechanic that will venture into this world of the predator realm with this knowledge. Thx
That brought back memories of my younger days messing around with cars. I did the heads on a 1990 Thunderbird I bought for $500 while I had it parked on a jobsite I was working at 20 years ago, and that was the last time I did any serious engine work.
Now I'm thinking gas powered table saw...
:)
Awesome video, David!
John, a gas powered tablesaw is worth at least 30 million views!!!
@@SomethingAboutMaking have you ever been to Keim Lumber in Charm Ohio? I think they have gas powered table saws for the Amish
@@beaushaw I've been! That place is incredible!
@@SomethingAboutMaking Are you a mechanic by trade? Great video btw! I subbed.
Delta’s “The Modern Motor Driven Workshop” published in 1930 shows how to hook a gas engine to their table saw of the day. They even go so far as to show how to rout the exhaust pipe out the wall of the workshop.
Racers today do not know how lucky they are having videos like this. When I started in the 80s, racers would tell you a little & the rest was bullcrap. You had to get pieces from different racers and put them together to get the whole picture.
When I started in the mid-90's, the guys you were competing against would outright lie to you. The guys you may be competing against in the future would tell you half truths and everyone else would just ignore you. If you wanted to compete, you either needed to find someone that had stopped racing and was just there to "hang out" or find an engine builder that had drivers in other classes.
When I was building a jet ski engine in the 90’s you waited every month for the current issue of Jet ski magazine.
@@aaronthomas6155 or do engineering. Usually this kind of knowledge you have to pay for.. but with internet being what it is today engineering can be done in your garage with a few videos. I took aerospace manufacturing and aviation maintenance, so I understand the principles that make an engine pur exactly how you need it
@@letitbe90210 I've raced against mechanical engineers. They were great at building engines but were horrible at setup and reading a track or weather. Not everything can be learned on the internet. Somethings only come from experience.
My 9 year old and I are getting into our first build. I'm sure I will be watching this video for many years. Awesome job and SUPER helpful. Thank you!
Idk how yt brought me here, but as a mechanic that worked in a bikeshop and tuned engines myself, I was very pleased to watch this. You explain things very well for starters with no needed fluff or editing. Great stuff! Hope you have a great day good sir.
Man, this is presented so well whether for a beginner or even someone like me who knows a ton about many engine types and is just getting into these. I wanted to know the reason why youre replacing certain parts for THIS engine so that was great!
Wow, great video ! I raced a McCulloch 101AA long ago. I think it was turning about 9k rpm on nitro 9 and variants. Of course, that was old technology that has been long surpassed. I never completely re-built one, so watching this was interesting. Even back then, it was amazing just how much science went into better performance. From frame flex, carbs, clutches, carb air flow "shapers", exhaust, tire compounds and on... So I can just imagine what's out there now, compared to then. Thanks for sharing !
As a machinist at a shop, what I recommend during the water leak test, actually fill the port and blow air against the closed valve. If you have air bubbles, gotta fix the seats 👍 Good video and interested in watching my work but on a smaller motor
Water has a lot of surface tension, kerosene or gas would be better for just a gravity test, but perfect for a 'pressure' test.
If you're cutting valves after your lapping you can use blue daikum and it will show your high and low spots if you have any if not it will be a complete circle around your valve and you can see a good seat
Lapping sooo important. Glad you covered that. So many people think the key holds the fw in place.
Pull your torque wrench instead of pushing. You're able to apply more force easier. Excellent video, very efficient.
Pulling is the correct way to use a torque wrench. Never push. You are absolutely correct
I'm learning! Thanks!
My wife wants to get back into gokart racing, she would've been doing races and shit when she was a kid but her dad started making excuses to take her. I'm getting it soon to rebuild and get her back into it. Definitely saving this video, you did an amazing job describing everything and explaining exactly why you make the modifications and their purpose for you. 10\10 my guy!
Depending on where you live, tires are a nightmare at the moment.
My dad always did the exact same thing. I would ride my go kart all day everyday when I wasnt in school. My dad would get my hopes up by mentioning go kart racing and I'd think that maybe he was gonna take me and let me do it but anytime I'd ask he would have some excuse why we couldn't. He never failed to have an excuse why we couldn't do something. I caught myself not long ago doing the exact same thing with my daughters and it made me feel bad. I have to learn to find excuses to do more things with them
@@Wreckz_TeaHey, my father did the same kind of thing with/to me, regarding making excuses. When my son was born, I swore to myself and my wife, that I was not going to do that to him. I had a good father, don't get me wrong. But when you tell someone that you are going to do something with them, and then the time comes and you make an excuse, it really messes with their mind. It always made me feel like I wasn't important enough, and gave me poor self esteem. Anyways, when I told my son we were going to do something, I made a point to do exactly what I had said.(But be careful what you say, because day to day life is hard to predict anymore) But I feel like my son grew up with a complete 180 degree view on his self esteem as compared to how I grew up. I am so proud of him and the father that he is, now. Also, he didn't go through all of the drug and alcohol dependency that I did, because of his self esteem compared to mine. Children's minds are very moldable, so don't make excuses for things that you said you were going to do. If you don't intend on following through, don't even bring it up. Just my 2 cents. Sorry for rambling.
Man I have never been into kart racing but I have to say I thoroughly enjoyed this video. From the detailed explanations to your fantastic cinematography and production. Absolutely amazing job with this video. 👏
Same here, took a huge dab and found this rabbit hole. This guy is super easy to listen to and watch and learn.
best thing I have seen this year, when I was 8 I had a 2.5 hp mini bike my grandfather did what your doing .... it changed everything . now I ride an nitrous R1,
I don’t even have a go cart. I’ve seen videos of people working on things, you are at the top in all categories.
When i first came across this video and had little to no experience with building or modifying these (or any) engines, I never got past the first couple of minutes.
Now that I have modified several engines and I'm always swapping or grinding something to pull that little bit extra power out of them, this video is way easier to keep up with.
I like the fast pace you've managed while being as thorough as this video is. One of the best clone building videos on RUclips, and Im confident because I think I've seen most of them.
Great job.
Some very useful information here ....glad to see someone working with what they have and not using extremely expensive machining equipment. To me this shows you can do it with basic garage tools along with a few specialty hand tools. Thanks for a very detailed video.
I used to be into yard carts in my early teens but haven't had any opportunities to play with them since. I watched this entire video from start to finish--man, what a great little intro to engine building! I've been a sub of Cars&Cameras for years, and have seen some of the stuff you've done on their channel, plus a bunch more from you now. Thanks for that. Really enjoyed this. Cheers~
Some of us don’t have friends….😂
I don’t have a kart but want one…recently started seeing these harbor freight engines popping up in my feed…the WANT is high! So much to learn!
This video was so well done, much better than everyone else who just says you need this part and it goes here, but never explain why or what it does.
This video had top quality production value. Well shot, paced, and very informative. Kudos to you sir.
When checking the valve seals you should use petrol or diesel, water is way too thick to test an air seal. Petrol will evaporate if left for too long so keep an eye on it
Yep....thats EXACTLY why you use gas! its a better indicator of leaks since its so thin and runny and water has too much tension.
A vacuum checker is the correct way to do it. The tool isn't that expensive either.
Yea we used acetone in my shop it’s super thin.
@@davelowets There's a correct way to do a lot of things, if petrol isn't leaking through however the compression is good. No one is buying a tool for a one time job, i certainly ain't
@@mrcaboosevg6089 Do the job right, or dont do it at all.
The zinc additive was removed from engine oil by the EPA in 2013. It's essential for any flat tappet or non roller lifter valvetrain. I'd use it past the break in.
Rotella T Triple and T6 both still contain zinc, the former in 1200ppm+ range.
grew up with guys like this teaching me in the early 90s. its refreshing to see what i learnt way back when still be very effective today good work man.
Came to this video by chance - was so full of knowledge and reminds me of 2 things - 1. A lot goes into these things, but 2. If one is willing to learn and put in the time, one can do this.
Highly appreciated!
I don't know why you waited so long, this is fascinating. I have no interest in go carts but I'll watch this all day.
Ha! Thanks Nick!
Thank you for the time and explanation !!!!
I have two karts and have always built my own engines and with the information from Jody and the awesome people at ARC, I've been very successful. And in my opinion your video is very good you hit all the bases without having to hear yourself talk like some do. Kudos to you, keep up the good work!
Jody Powell knows a this or 2
David, that was brilliant. You are an excellent teacher. I've watched tons of "engine" videos but this made it simple for me because there's only one piston to worry about. Thank you very much for that. New subscriber.
I have been into karting since 1985 started in jr. stock and have raced Stock Appearing and Open Modified. It’s such a blast.
Wow...Just a high school and college kid when I "built" a Ford 289 for my 65 Mustang and a Honda 450 DOHC motorcycle engine. Fiddled around with porting and polishing with a piece of plexiglass and a graduated cylinder from chemistry class. Your video is so detailed, practical, and precise I was remembering my youth and my uncle "MC" who was a master mechanic from a young age. Sure read a lot of "Hotrod Magazine" back then. I do remember a speedy "racer" gocart with a McCulloch 2 cycle engine that we rode around the neighborhood as kids. It made so much noise we got an unpopular reputation in some areas. GREAT VIDEO !!
I don't race, but this video makes me want to modify my lawn mower engine...
I was thinking the same thing until I thought about the blade coming off at 8000 RPM
Do it on your rider.... it'll go faster, you'll get your lawn done quicker, and you're sitting on top of the blade, no getting ankled like you would walking behind your push mower, if the blade decides to go for a cruise.... 😬
😅right
Those HF engines are no joke. I've been seeing them used in a lot of places, especially over similar Hondas. similar power and reliability for fraction of the cost. It's pretty cool. I'm debating picking up a Predator engine (non-ghost) for my kids' yard kart just to replace the finicky one that's already on it.
That sounds like a plan Dad.
I know so many people where if price is a big factor, predator is always the immediate choice no matter which version
Get the Ghost!! The extra few bucks is completely worth it otherwise the cart will sound like a log splitter
Get it, I put one on my daughters go cart and it does about 35 with me on it at 200lbs. Non ghost
@@brodieodell1974 I have to fix the steering before I worry about the engine. My oldest sent himself to the emergency room when he ran head long into a tree with it. No point in making it go if you can't tell it which direction to go.
Circlip tip (7:30): make sure the opening is facing up or down, relative the stroke. If the opening is to the side, at high RPM the G forces can compress the clip enough that it can come out. Overall an excellent video! I don't even race carts and this makes me want to build one. :) How do these things hold up with splash lubrication?
Don't ask me how I found out circlip location was critical.
@@mmi16 How'd you find out circlip location is critical?
And that's why I love Spiro Locks instead of Circlips for wrist pins haha.
Easily the best video building out a small engine ive seen and ive seen many you explained everything that you talked about explaining how and why you are doing this modification, well done
A tip I picked up from somebody that rebuilds motorcycle engines is to build yourself a small open square of wood out of two by fours or maybe four by fours and the engine case will sit on top and inside the square and not move around so freely on a flat bench. It’s sort of hard to explain but in essence it’s just an open square of wood that’s tall enough to allow the engine case to sit proud of the bench top. It’s so simple when you actually see it but I never thought of it myself. It really keeps the case from sliding around on the bench.
The Ball hone achieves something akin to a sandpaper finish, the long chain hydrocarbons in the oil that offer lubricity between piston and bore get sheared quicker and the oil fails sooner affecting the rest of the bearing surfaces. Buy two of those 3 arm sprung hones, one with course stone and one with fine stone and build the hone finish properly. Piston rings are designed to hydroplane along the cylinder wall on the oil caught in the "deep" hone. The initial overlayed shallow hone atop the deep hone is meant to abrade the rings to a mating surface H7 fit. The light hone is at the same time abraded away to form plateaus atop the deep hone peaks, this is the breaking in process (breaking off the minor peaks). The deep hone valleys anchor the splashed oil till the rings shear through this oil then, hydro glide across the plateaus. That said the ball hone is a mongrel tool that doesn't deliver the engineered principles desired. Yes ball hones seem to work but not like the proper hone finish. When you're chasing performance (HP & longevity) for 7000rpm average make a torque plate and bolt it down to simulate the head, this will twist and bulge the barrel, the course honing will return the bore to cylindrical, reduce piston flutter and oil shear so more power. Apply the course hone with faster reciprocating action for a more acute (60/30) hatching in line with the bore to allow for easier oil shedding, the light hone can stay at 45. Coning the bore off perfect cylindrical 2-3 tenths larger at the bottom for reduced friction adds HP and longevity as the effective pressure is so much lower at the bottom and doesn't need rings shearing the oil to form as great a seal. The piston could do with an oil hole drilled through each wrist pin boss for better friction management so more power. The piston skirts narrowed give better engine acceleration and lower peak impulse load on the bearings, the piston skirts aren't cylindrical and examining an old piston will show the "contact" patch you can machine a new piston skirt upto. Finally turning the piston around will give you slightly more compression but more slap and wear, it's a geometry thing. You skipped over performance valve and seat prepping, guess that's where you've keeping true to promise.
I'll apprentice under ya
First, love the video! First time I've seen any engine builder go through step by step of what is necessary for a competitive motor.... for any kind of racing.
I can say that in the car engine world the rings vs. bore finish have come a long way. Very thin rings vs. finely finished bores etc.
The ball hone gives you the cross-hatch pattern which helps leave some oil on the walls. Then there is ring gap.... It used to be the bottom ring (3 ring package) was gaped smaller than the top. But apparently that leads to flutter on the top ring. Of course you want to go with the lightest piston (reciprocating mass sucks for power). Roller bearings on the cam.
@@confuse9 What's come along way is thermal management. What's changed is the compromise delta. As bores maintain cylindricity over the wider thermal range, manufacturers have reduced compensatory design (clearances for thermal change, ring pressure, film viscosity). Shorter chain oils, and lower spring pressures means lower drag so better (fuel tank) economy. This requires a very accurate ring on oil to bore calculation. Throwing a ball hone in modern, low ring pressure, engines cant achieve plateau requirements as it cant in older engines either. Look at Audi over the last 15 years and you'll find increased oil consumption rates as they chased the low internal friction delta. Audi's bore finish breaks in almost immediately and has the right ratio of scratches (valleys) per area for oil retention but not (**see service manuals and law suits) over retention. Best use for a ball hone is to remove grease and rust from a block prior to proper machining. Aging a block in the back yard or grabbing a high mileage block from the breakers is valid but really harsh on workshop machine tools. Emery taping the deck faces and ball honing the cylinders saves expensive carbide inserts from cutting abrasive oxides, that's a good use for a ball hone, as a heavy duty cleaning brush.
Been building for years, only now did I come across such detailed and invaluable information. Thank you.
I agree with you 100%. The cost and time to hone the cylinder correctly will add longevity and keep more HP longer. Definitely worth buying a set if you are going to build more than one engine.
I will 100% watch every video like this you make. I love the mechanical workings and visibility of all the gears. Not to mention I love tearing down and rebuilding small engines like these.
Thank you!
Great video David! I'm a FAA A & P, , and I'd like to share nothing happens without "ignition". I hope you'll find the aviation version of the internal combustion cycle to be more accurate. Which is: 1) Suck, 2) Squeeze, 3) IGNITION, 4) Bang, 5) Blow. Great tech video, , you point out ALOT of very good tech points and assembly processes for high output engines! Lastly, you have really good production (sound, lighting, layout and editing) values. Loved it!
Aircraft engines don't operate on the 4 strokes, intake, compression, ignition, exhaust?
@@genefogarty5395 Gene, yes they do. Please reference any aircraft mfgr's piston or gas turbine engine operation discriprion. You are misinformed or do not know the facts with gas turbine or high bypass gas turbines. These are commonly called "jet" engines. . I'd recommend reviewing the Continental IO540, a 540 cubic Inch "Opposed Piston" with ovhd vales. Or the Pratt &Whitney 4000 GTF (Geared Turbine Fan). A typical jet engine has multiple rows of compressor blade. Then multiple rows of blades in the "hot" section. The air enters a typical gas turbine and is very highly compressed. In some engines it's compressed from static atmosphere pressure of 14psi (sea level) to >200psi. in the "Compressor" section. This very compressed air flows into the hot section. Kerosene is injected at very high pressure and inside this "hot section are "IGNITORS". There are two types of ignitor systems. The continuously "sparking" ignitor or the continuously "Hot". These "ignitor's" are needed to ensure that the kerosene gets ignited in a very high pressure and very, very turbulent gas flow! This flame front then expands the pressure in the "hot" section by 5X or more! This pressure then expands as it flows across/through compressed hot section blades, creating a massive pressures and force. This gas the exits the jet engine via a third set of compressor blades called the "Re-Heat" stage. So, in a nut shell, it's Suck, Squeeze, IGNITIO, Bang, Blow! I hope you have benefited from today's class. All the best, TAC
@@WestKyCrime This was a 4 stroke ICE, not a jet, dude. It's still intake, compression, ignition or bang as you call it and exhaust. Ignition and bang are one and the same. There's no delay, it's an explosion. But thanks for the "Class"
@@genefogarty5395 sure, we all have our opinions. Let's walk thru what happens in a ICE ignition event. And I'll try to see if I can convince you why Ignition is its own "event" in the ICE operating process. The crankshaft magnet on the flywheel (engine in the video) passes by the stepup voltage transformer. The magneto (AKA a very strong magnet). The step up voltage coil then excites the main voltage step up transformer (AKA as a "coil pack"). Once the voltage exceeds the ignition systems regulator (AKA as a special type of capacitor), this high voltage then seeks a path to ground. And "wah-La", it's ignition time. Bang occurs AFTER this above ignition event. In closing, I bet you will agree, that the first thing experienced technicians ask when trouble shooting a ICE is, "Is it getting Spark"?. Next question is likely "is it getting "Fuel"? So, I hope you can now agree that "Ignition" is its own event in Petrol ICEs. All the best Gene.
@@WestKyCrime It's a 4 stroke. If there's no intake air coming in it won't start, no compression, no start, no spark, no start, no exhaust going out, no start. Pretty simple.
Second person that I am aware of that can explain everything simply, not over-complicated, and not too boring.
I think i learn more from youtube than i could in college. One day I'm learning how to change belts in a tape deck, the next day how to build furniture, then the next day how to re-build a go kart engine. I didn't even seek this out, it just got recommended to me like everything else. But, now I know how to do it.
Thank you David for putting this video out. I have been curious about the process and this will be a GREAT resource in the future for lots of people. You first teased this on the podcast and it had me intrigued, great information throughout the video. 👍🏻👍🏻👊🏻👊🏻
Commonly I see isopropyl alcohol used for checking the valve seal before the first heat cycle, but always remember that if you have teeny tiny itty bitty leak, the chances of it sealing after running for a break in are almost 100%
I second the isopropyl alcohol...
Alcohol's for drinkin', lighter fluid's for checking valve seats 🤣🤣🤣
This just popped up on my feed, and it's such a well done and organized video, you can litterally feel the amount of effort put in as you watch it. I decided to subscribe and go through your channel and you litterally do everything, which is so cool to me. Will be watching many more videos from you.
maybe it is you that is responsible for that abortion called the Animal.
I don't even have a kit car, but there is a kit car track track in my small city where I live. It's 2:00am after getting off work watching how to build a built engine for a serious go kart track.
Well done sir!
I will never build my own engine/cart. I will probably never use this knowledge in practice but it was nice 43min with you and even as I'm non native speaker I had no issue to follow what are you doing and why. Great job. Thanks to people like you, the internet is better
This is super cool man! Been playing KartKraft in VR and would love to do some IRL racing.
Do it
Nothing like real life!
If you’re doing street course racing buy a Briggs Lo206. They run them about everywhere while the predator stuff isn’t ran anywhere I know of
@@dondelchulia3189 the Predator is gaining traction FAST so it depends on the region and if its "box stock & sealed" rules or not...you can build a BADASS predator for about $650 all in that a box stock $600 Lo206(Undressed at that) cant even compete with. And that can be upgraded even further without much more than a cam/spring swap. Around here, almost all Kart classes allow predator based engine....even some predator based Jr. Dragster classes are common at the strips around here now
7:43 With a Trabant engine the entire cylinder is a piston ring compressor, it's tapered and installs after the piston to the block. Off topic but just realised how neat it is
“Some of us don’t have friends” That really hit home
Awesome! I learned more about engine building, building any engine, than I've learned by osmosis in all my years of working with gasoline engines. Excellent material. A Master-Class in engine building.
I have no need for a "competitive kart engine, but what a great video, clear and well edited. (Two stroke tuned scooter fan)
Just a question: by changing the connecting rod and piston, as well as removing material from the crankshaft, wouldn't the crankshaft require rebalancing to accommodate the changes especially since it will now be turning at 8,000 rpm?
Possibly but I have not had issues
You have to remember that these motors are a single piston motor not a traditional motor with 8 cylinders that spin the crank at once. So take the side cover off of a motor and turn the motor over. There is only one point where the motor is perfectly balanced and that is when the crank is completely in line with the rod and piston. The other 99% of the time the crank and counter weights are not going to be in that position. I hope that was easy to picture in your mind. But to answer your question plainly no you never have to balance a crankshaft in a single piston motor. The only thing that you really should do is make sure the bore is true.
@@JakeSeiner That was a fantastic explanation. Thanks Jake.
@@SomethingAboutMaking Another tip that people don't really let out is call JC Specialty up and order hardened side cover bolts this keeps the side of that block from flexing with those oem bolts. I know it probably sounds silly but it adds a substantial amount of strength to a predator block. Considering that predators are the weakest blocks of all the clones this is a must for every one I build.
@@JakeSeiner well excuse my ignorance. Just assumed swapping out stock heavier con rod and piston for lighter components would require balancing, especially taking an engine meant to rotate at lower rpm's and pushing it out to 8k. But I have never souped up a lawnmower enigine.
Too bad you dont have a way to dyno before and after. I'd be interested to see the difference it makes. Also, can you please explain why tf you have a background that makes it look like you're rebuilding go kart engines in a preschool? It really makes me feel uneasy about this whole thing
Wait, so you can't install a separate stroked crankshaft because that's against the rules, but lengthening and increasing the compression is totally acceptable? That makes literally no sense 😂
I didn't make the rules.
Ya, my friend did this kinda stuff carting as a kid. 40yr old MF'er still proudly displays his trophies.
You're all frigging cheaters who, like Tom Brady (who I like for a lot of other reasons) must win at ALL COSTS. What cost is it when I think you're a frigging idiot cheater? If you do this with children, you are seriously mentally deficient and need your head examined.
This is the kind of quality content that makes RUclips worth existing. Thank you.
Informative, not overly technical, but touching on all the key areas of modification. Well done!
You are watching my 2nd channel. I don't post here very often. Check out my main channel for all the cool builds! ruclips.net/user/makesomething
To check valve seal I always used brake clean (thinner than water) and used a air gun and a rag to "seal" and look for bubbles. Not sure how correct this is but I've identified leaky valves this way
the bearings will love all that metal shavings from the milling.
How much you charged to get one build man
Is that drill Festool? Looks like it but doesn't sound like it. I've been using mine daily for almost 15 years. Incredible quality. Thanks for an interesting production.👍
Did you grind on your crank shaft? Doesn’t that create harmonic imbalances?
The most concise and detailed video on RUclips for building a Predator engine. Thank you for taking the time to explain the steps that go into the art of building a race engine. You have a natural talent for teaching. I am a new subscriber, and thanks again for the information.
I don't have a go-kart but love to play with engines this video was so complete i watched it from a to z.Thank you for taking the time to make this video. Even a noob can have a good idea of how a gasoline engine works.
Respect for diving into a subject, parsing the info, and presenting it in an easy to understand medium.
::side note:: I bought a dirt bike when I was 15, disassembled it to repair, and never got it back together! 🤣
65+ years of studying engines and you did a credible job of explaining the rationale for modification in less than an hour. Great job! Definitely can’t afford to do what you have, but the bug is still there. An additional note - 1.3 million views, 50K subscription, 21K likes. …? As if it costs a second to acknowledge that you did a ton of work using a thousand plus in “props” doesn’t seem credible. I had to scour library’s, spend limited income, and thousands of hours of research and today it’s difficult to actually click on the thumbs up icon. Huh
Excellent video, easy to understand everything. As an old kart racer back in the early 80's you brought back some great memories. Now i just rebuild Vittorazi Atom 80cc to stock.
That was a great ending building video. I used to build those engines for a friend who raced. I did not know all those cylinder head tricks except for stiffer springs and milling the head. I started safety wiring the side cover bolts cause of a failure where they loosened and ithe engine blew up. He had the same header as you, I wrapped that with DEI header wrap to prevent burns. I made a tool for holding the crank to the block for torquing the flywheel nut. For removing the stock flywheel I drilled and tapped the stock flywheel 3/8 nc and used a steering wheel puller to remove it. The same steering wheel puller with different studs would remove the ARC racing flywheel.
I am not used to seeing people working on these types of engines as go-karts. In Australia we mostly see the smaller and much much faster 2 stroke engines in our professional go-karts. If it cant reach a minimum speed of 100kph / 60mph then it is considered a toy for small children.
Your work in stripping and then altering and hotting up the engine is well done and amazing to watch. Well done! :)
It isn't uncommon to spend $6000 to $10,000 on professionally built 2 stroke Go-kart engines.
Good friend always told me it was cheaper racing Formula Ford that it was racing in the Go-Kart State and Country wide Nationals.
I do Most of this when I build stroker scooter engines and alot more little secrets. I'm old-school kart builder but we only had flathead engines back then, but we went over and beyond of what people thought was impossible back then alot of secrets Lol. This is a very informative/awesome video for anyone that needs a little more kick on their mini bikes or karts.
Mate I’m a heavy duty mechanic by trade and build manuals and do maintenance consulting. There is companies that would pay to have you do their rebuild and educational videos. You’re concise, well informed and the presentation is easy to follow.
Seriously something to look into.
Take it ez🤣😂
@@mc4492 yeah what do I know lol
haters gunna hate
I've never raced carts and likely never will. However, this video was a super fun watch. I like engined and tinkering with things. So, thank you for the informative and interesting video!
sir i am NOT engine savy but as im watching ur vid, it makes me wanna go build my own go kart. the vid was very detailed and easy to understand.. also very enjoyable to watch.
Really love the explaining everything in detail. Someone like me has general knowledge, but has never taken part of motor feel after watching your video could tackle a job like this 😎
Thanks, I’m glad Harbor Freight offers an engine of high enough quality that you can take advantage of their prices.
I can’t get past you had this other account for something else than woodworking! 👏🏻 🙌🏻
Man your awesome I have been looking 3 years for videos like this I enjoy restoring and creating modified go kart people throw away, I bring back to life
By far the best small engine guy I've seen in a long time 💪
As said by others. I'm not into karts but this video kept my attention all the way through. Well done.
Just got into mini biking and damn this is the definitive video. Great job.
New sub....anyone that explains a process so well and clear with no fluff means they completely understand what they saying great work good video thanks
You know what? You do an excellent job in every aspect of a how to video. Probably why you have success in the other hobbies you do. I wish you luck in your races!
For leak testing your valve seats I always used alcohol with a little bit of food coloring in it because alcohol is thinner than water. Great video 😎
I've never seen anyone so serious about amping up what starts out as essentially a lawnmower engine. Cool project!
I USTA use gasoline., or rubbing alcohol to check valve sealing. It's a little thinner than water. Great explanation on everything. Great video
i like that your going through all this. back in the early 2000's i used to race a class that was based on the briggs animal 6.5hp. It was an open class, the only requirement was that we had to use the briggs block, everything else was fair game. At one point we had a dome piston, roller rockers, custom cam, and even had machined the head to accept valves from a honda civic along with many other things done to the head. made almost 50hp. raced on a short flat dirt track, if you can imagine we ran a 11thooth on the clutch and 68-70tooth sprocket. I would say our most reliable versions of the engine had flat top pistons and briggs valves with mainly a worked head and custom cam making about 30-35hp. Our big engine does hold the lap record though.
Just listened to the podcast yesterday where you said probably no one would watch this, glad you were wrong! What a great video and response
ha! Thanks Craig!
Bravo! You were very thorough. I can’t imagine what little secrets you were keeping. I’ll have to give that some thought. 😊
Nice job. The details were great but the racing video at the end is the perfect finale. Looks like a real blast racing those small karts in such a tight little track.
Damn bro, you definately earned that thumbs up! From idea to running bike is brain shaking. And how smooth it runs! All yours bro. Amazing! One of the most ambitious projects I’ve seen pulled off on RUclips.
I raced in IKF 4-cycle Stock Heavy and Super Stock classes on dirt tracks in the Midwest for 15 years. I was also one of our local club's technical inspectors. This was back when IKF ran the 5 h.p. Briggs horizontal shaft engine. We ran on 100% methanol. We always clearanced our engines which reduces friction and increases hp substantially. We would always run a worn out top oil scraper ring to reduce friction. IKF 4-cycle engine technical rules didn't allow the oil ring to be completely removed. It just had to have one. Since oil consumption isn't a concern we just ran a worn out one. The IKF Stock light, medium, and heavy classes had to run the stock Briggs carburetor. We ran Tillotson carburetors with billet aluminum intake manifolds in the super stock class. I actually ran Klotz KL-200 fully synthetic 2-cycle oil in all my engines. I had absolutely no carbon buildup whatsoever. Since Klotz didn't specify the SAE weight for their KL-200 oil at the time I measured it myself. I was a mechanical engineering graduate student at the time and was performing SAE viscosity testing on biodiesel fuels at the time. I measured the Klotz KL-200 fully synthetic oil to be in the range of an SAE 50 oil. The one thing you don't want to do when running on methanol fuel is to leave it in your engine for extended periods of time. That's because methanol is highly hydroscopic and will attack non silicone (red) gaskets and seals. On my superstock kart I had a quick connection in my fuel line running between my belly pan fuel tank and Tillotson HL336 carburetor. It was a quick connection with automatic shutoff valves on both sides. I made a gasoline flush tank from a one gallon plastic gas can with a short fuel line and male quick connection with shutoff valve just like the one connected to my kart's fuel tank. After every race day I would unplug my quick connection on the kart and plug in my flush tank. I would then start the kart on methanol left in the fuel line and carburetor until it was running on gasoline from my flush tank. I had to pump the throttle lever on the carburetor to keep it running on gasoline. I didn't connect the methanol tank to the carburetor until the next race day. By flushing out my carburetor with gasoline in this way, I never had any methanol related problems. Since methanol is highly hydroscopic always keep your methanol fuel sealed up tightly. Otherwise it will absorb moisture from humid air.