Yamaha RD400 Race Build- 65 HP
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- Опубликовано: 12 сен 2024
- Sharing my build of a 1976 Yamaha RD400 full race engine.
Techniques shown include engine assembly, measuring port timing, carb build, expansion chamber exhaust design and fabrication, dyno test and more.
The RD400 is a long stroke version of Yamaha's RD350 two stroke. The same tuning techniques can be used to build a RD350 race engine and exhaust.
This is not a full tutorial on everything involved with an engine build. It does not show final jetting or proper operation. Air cooled two strokes require precise jetting to allow full power available and not seizing or detonating the pistons. The life span of the pistons is short compared to a street engine.
Motorcycles are dangerous. It is the responsibility of the mechanic to build a safe engine. A blown up engine or oil leaked on a tire can cause a crash that may seriously injure the rider.
This video is backed up with decades of professional motorcycle mechanic experience. This is not a how-to video for a novice.
Viewing notes:
Click on the settings icon to playback at a faster speed.
Highlights:
0:06 Engine assembly
31:23 Measuring two stroke port timing
41:14 Ignition timing with PVL analog
41:46 Carburetor build
52:12 Exhaust design- expansion chamber
53:24 Exhaust fabrication
1:42:49 Dyno testing on Dynojet 250i
I've never split the casings on my rd400 because I was absolutely terrified of what was in there, but now I see that it's not so bad! Thank you for such a detailed video now maybe I'm not so terrified if I have to get in there.
Just take some photos of it as you take it apart, I did mine once and now I'm confident - easy bro
I bought a 1978 RD400 from Freddie Spencer's dad in Shreveport back in the day. He built it for a box stock race Freddie won on the bike. They had milled the ports as you have. It just sputtered until it hit about 6000 RPM's and then ran like a dream. That bike would smoke 750 Honda's like they were standing still. Hard part was keeping the front wheel down. Wish I had kept it!. Thanks for the video.
The sputtering could have been fixed with the correct carb settings... Knowledge is far more widespread now, as is miss information.
We raced against Freddie and that bike at a WERA race at AIR in 1978 and both he and the bike were fast. He ran in several classes that day and I think may have won all of them. Just a sample of what was to come.
Interesting. I did the same to a 350B engine in a 250C chassis back in the day. We probably optomistically guessed it was around 60 hp, but never had it dynoed.
I rode the RD 400 for two years and it was the second bike in my life. I'm still dreaming of this little beast, love it!
Built my racing RD400 back in1981 down here in South Africa. Did all my own porting, pipe calculations, etc after studying a book by Gordon Jennings, Two Stroke Tuners Handbook. Was always amazed how the engine did exactly what the calculations said it would. My own idea was fitting 32mm Mikunis and reedblocks from the YZ. They were power jet carbs that had 2 main jets that opened at 1/4 throttle and then at half throttle for better mix through the range. Won a number of races with it and always mixing it up with the "big boys"..
Awesome Stan, takes me back to the 80's brilliant stock bikes but tweeked were awesome, we used to have a tuner in the UK called Stan Stevens, reknown for Yamaha tuning.
Thanks for the comment, giant killers for sure.
One of my life’s greatest regrets is not keeping my RD’s, I miss those little screamers so much I dream about them constantly.
Every neutral light switch in the whole wide world has at least one screw hole crack.
Mine had one from the factory in 1975, and STILL does.
IMO, the best motorcycle ever!
Don't tight these bolts all the way just use thread lock and back them out just a little after contact
True about the stock plate and because of this they leaked. Best to make a block-off plate and carefully seal it (w/o the ball bearing and spring ). Don't need a light to tell you you're in neutral . Do ya ?
Very nice. I have a 77 RD400, CNC machine shop, Haas MiniMill-2 , and Solidworks. I also thought about building my own chambers. This video is a perfect for me. Thanks a million!
I use to race a RD400 back in the 80s. Best setup was lightly ported cylinders, 34mm Mikunis, Erv Kanemoto’s pipes, motoplat ign. It would pull strongly from 6-9,000 and outrun most TZ250s. Last build was with Fahron cylinders, TZ350 dry clutch/primary gears, and cr gearbox. Never got the setup right and retired from racing. Still have the bike, old setup w/cylinders and oem clutch/gearbox, brand new RD400 cases, extra cranks, pistons, etc.
Thanks for sharing.
Hay Stan, it's Joe Reisinger. It's nice to see your still in it building motors. Hope you're doing well. Take care and Happy racing....
Thanks, you too Joe!
hi stan something you may find intresting the harry barlow interview 91 92, me and harry took the engines in the interview to microns dyno with getting to engine to 86 bhp which at the time was the fastest rd in europe at the time , but one faster in the states at that time, but think with todays metals and tech , and measurement it be easy to beat now , one of the main things we had to cope with was getting rid of the heat, and thats why it all went watercooled ps farhon did a watercooled kit for the 400 which i raced aganst which was no faster at the time , got down to some really cracking time on my rd then 55.9 at mallory and 1,11, 3 at cadwell in the end was good on holding together , even use to run them in on the road in a road bike
Stephen, thanks for your excellent comments. Harry tuned the fastest RD400 vintage (Classic) roadracers that showed in the n US, Chuck Quenzler and Chris Spargo, both reported to dyno at 75HP at the rear wheel. Barlow was and is the master of RD400 tuning, probably the fastest bikes at the drag strip. Road racing an air cooled bike, unfortunately, has to abide by the rules of physics, there is a limit to how much heat can be dispersed. Actually, air cooled race motors are tuned over that limit, and rely on excessive fuel to cool the engines. Water cooling and nikasil aluminum cylinder bores was the solution that allowed full power cooling on the TZ race engines. I am representing a more-than less reliable roadrace tune,
Cheers, Stan
@@stanlipert8513 it was great for me to be one of Harry's sponsored riders here in the uk before Harry went to the States we even had a last team meeting and meal the day before he went . I was going to try and get out there but never got . Think he ended up at star racing . But told he's back in the uk somewhere . At the time he and rex sorted some programable box's for the timing which mega at the time as even works yamahas had only just got them . Was a big part of my life then . Wish I could turn the clock back now. But great memories.
What a beautiful restoration
Nice!
I have an newly purchased RD350 1975.
Looking forward to restoring it.
Thank you for the upload, from Norway 🇳🇴
Fascinating. I owned a 400DX bought new in 1979 and did a bit of work to it and it was pretty quick but I didn't modify the porting to shift the power band to higher rpm as the long crank length would stress the stock pistons. The most insane RD400 I ever rode was a full race tuned model (or maybe even beyond race tuned). The barrels had been jacked up at least 3-4 mm and this thing didn't even start to make interesting power until around 8000 rpm and would pull all the way to around 11,000 rpm indicated (way past the stock red-line). My friend let me ride it and it was insanely fast - it absolutely smoked a Kawasaki 4-cyl Z650 which in its day was quite a fast bike). Revving to that level however, was not good for the pistons or crank and the pistons did let go at some point . . . . they had been radically modified with the skirts cut away and the metal between the "holes" removed.
Yes, a 11K redline has a very short fuse indeed, this bike is tuned to a 9.5K RPM redline for better reliability.
Great video. Dedication, enthusiasm and skill, all in one.
Great video!!! and outstanding work!! I got a 79 RD400F Daytona Special I need to get back on the road.
Wow. There's alot going on in this video. Great job and thanks for putting it up. And thanks for not putting goofball music in it.
Play you own music!
Amazing work. I’ve watched your video a couple of times now so I could prepare for my own RD400 rebuild. Thank you!
I would really like to build my own expansion chambers. I know that each design will be specific to the build, but I’m wondering if you’d share the files you have so I could save myself a lot of head scratching?
The Ian Williams Tuning software is a good place to start in designing your own exhaust chambers.
Thoroughly enjoyable watch from beginning to end, thanks for posting.
Nice build, saved it for my rebuild.
Nice bike, sounds lean on the pilot though. With my tuned 350 I needed more cc on the recut heads to stop pinging when hot, I used 21cc and then a Zeeltronic to map the ignition to suit and now its got the torque and revs more freely.
stan the man. post more.
Stan- verry impressive - thnx for your sharing your knowledge!
Excelente trabajó
you are welcome, just sharing my experiences.
Awesome video! You are really fast, and no shaking hands - heh heh.
Thank you so much for your time so cool 😎 I have a 79rd400f,,apart right now,, this video and all the pictures I took and some payers and some luck,, I will get it done
after watching this, I wish I still had mine!
Awesome skills, great video. Thank you
That was excellent, thank you Stan.
Nice! Looks like you might have done this a time or two lol
oh…wow! I didn’t know This was going to be This, and This is incredible. especially for those of us who are willing to go these depths, but haven’t completely assembled or rebuilt one before.
thank you for sharing your skills & abilities here.
is there any or much difference between the RD350cc & 400cc engines?
-not asking for a friend
Thanks for watching!
Nice bike, i wish i still had mine.
You can tell this guy knows what he is doing by looking how he works and handles tools. Clearly a veteran technician and has had this bike apart dozens of times.
I’m doing a resto mod of 79 400f. I’ve heard the crank is junk. For near stock hp, will it hold up fine for street and the occasional track day?
Also lots of people hated on me for using prox lc pistons at 20 thou clearance. What say you???
Beautiful bike,you've done an amazing job
A real fire breathing beauty!!
I rebuilt a 76 RD400 back to complete stock set up.. from what I read online Yamaha states 44hp but I just dont buy it. The bike isnt a complete slouch or anything.. just doesnt feel like near 45 hp to me. Still love the bike. I love that you built your own chambers.
Motorcycle manufacturers typically give horsepower ratings measured at the crank or output shaft. A stock RD400 measured on a dyno is around 33-34HP.
44 stock hp rip wheely's on that light bike. Few years later Yamaha was getting 80-90 hp out of there F2 250 technology Friend on mine races go karts competitively was using cr 250 single trans cut off. Collapsible expansion chamber. Making 80 hp. Had to compete in the 450 4 stroke class.ranked 17 nation few years back. Then he dropped his pants went 4 stroke. I miss my Kawasaki triples my rds Got a 01 1200 bandit roller. Thinking about 2 stroke 1000 twin 800 triple snowmobile motor. Drag race it. Be Cheeper fun.
They made around 36-37 at the rear wheel so not as many as a current Ninja 400 but they were excellent for the day.
@@guylr7390 - yes - I just got back into riding recently after a very long break. I bought a Ninja 400 in order to break myself in gently and also for my son who was a new rider (its fast enough to have fun but not so fast to really get into trouble on). The Ninja is certainly faster than my old (1979) RD400 but it delivers peak power at 10,000 rpm vs the 7500 rpm of the RD400. While I like the Ninja, I was surprised at how little things have really advanced in roughly 30 years although the Ninja has much better fuel consumption than the RD would ever get. I subsequently bought an FJR1300 which is a lot more comfortable and does everything I need effortlessly.
Nice Build! Sounds good!
I replaced the shifter forks on one of those.
However, I was living in a bed and Breakfast in London England.
The Landlord was not happy when he found the engine under my bed.
Well done sir, thank you very much.
You are very welcome.
Out standing job!!!respect!!
great job well done
Real Nice! If I were putting a bike like this together to ride on the street would it be better to keep the oil injection or is pre-mix ok to run for extended miles?
Honestly, you would not ride this on the street, unless you were either full throttle or closed throttle. If this is ridden at half throttle, the pistons will overheat from the exhaust gasses.
Fit a thumb operated ignition cut-out, so you dont have to use the clutch when changing up, throttle wide open, touch the cut out and change
I chop the throttle for up-shifts, works well. Some transmissions need to be nursed gently.
@stanlipert8513 when Racing one Never Never Never, closes the throttle,, Never
Nice work, this has helped quite a bit. Can you suggest someone in the US that still works on RD's. Ive got 5 Daytona's, one from high school in 85. I'm at a few impasses on different bikes. Need help, will drive them anywhere in the US. Thanks
Kon Tiki motorcycles in San Diego has a long history of rebuilding 2 cycles. I think that I am going to take my 77 RD there.
@@gregorypenniston7742 ThanksGreg, appreciate the help.
Super talented!!!!
Super cool. Is there a particular reason you used gas welding instead of TIG or TIG?
My TIG welder sucks (lift-start). Oxy Acetylene works well.
great job loved those engines we raced them back in the late 70's and early 80's put them on mini sprints . have you run them with the 3rd hole in piston ?
Excellent. thanks for sharing that.
beast mode
Hi, great video. Question. Does the clutch cover needs a gasket, sealant or did I miss something? Thanks
24:00 Gasket is on the cover.
Nice .
Stan, nice work. Are you for hire to do CB350F engine work?? Thanks. Don
Sorry, no. I only work on my own bikes now. Mechanic for 37 years. Thanks for asking.
Was a extremely fast rd400 in Sydney Australia methanol munching drag bike known as TIME BANDIT
Piss easy too rebuild splined centres on crank my daughter could rebuild
@@garrylawless6758 yep.
So schöne Yamaha, und die Doppelte Leistung getunt ,gutes Ergebnis .
superb.
Brilliant helpfull video . Does the ignition use a battery ?? The tuning software , expansion pipe design ??
The ignition uses no battery, the software is as displayed in the video.
Is the Ian Williams Tuning software, is it better than other offerings for pipe building? I noticed that you didn't show the head pipe build. It appeared to have longitudinal welds rather than small cone build. Would you be so kind a get me straight on it.
David, The headpipe is reused from another chamber set as a matter of convenience. I have not tested and built chambers from all of the other software, but this software compares well with my previous RD chambers and tested on the dyno.
In the early seventies Yamaha rd350 was the fastest motorcycle ever built to make it Coast to Coast Non-Stop. Never see a 400 make 65 horsepower at 9000 RPMs with 29.8mm carburetors good job, bigger reeds and carbs and modified petcock, get's more Power
🔝🆙️ Well done! Sir, Outstanding Work thank you very much.👮♂️🏍💪💫
Hey stan I would love that you build my rd350 1975 , Also being ur apprentice I would love that
I noticed no modifications were made to the reeds , why was that? Is this maybe built to a formula to race in a class that doesn't allow mods to the intake? Because if you fit a set of Vforce 4 or even 3 made for the YZ85 is a drop in mod and if you complement with a set of Mikuni TMX 30 you gain a massive improvement on the mid range and also top end
I see now you know all this and much more better than me. It was a pleasure to watch you work with a staggering level of confidence. Very nice thanks
I did hog out cylinders at one point and dyno tested big reed cages and big carbs, but no real increase in power. One of my old competitor's uses big V-force reeds and big carbs but dyno's at the same HP. He is not a mechanic or tuner, so he is sold on what he is told. Thanks for the comments.
@@stanlipert8513 hey thanks for your reply. I own a RD (RZ in US) 350 and it was bone stock still with stainless reeds and then the Vforce for the banshee came out which is exactly the same reeds and when I switched them wow it made a heck of a difference specially in the low to mid range I was pleasantly surprised and later the flat slide carbs which are just 30mm made it even better all the rest is stock. I thought it would work for any bike but I guess I've got some learning to do. All the best thanks
You're both right. The stock 28's to 29.6 are the same as the TMX30 carbs and Fernando did not say hog out anything but drop in diff. reeds and/or cages. But he's still talking apples to oranges because an RD and a RZ top end are way different. Still, 65 hp is no joke and this is a GREAT video ! Kudos to you Stan ! Sean, old AFM #137. @@stanlipert8513
Hi, are you in the UK or over the pond USA?? Thanks 👍
Ohio, USA
Hey man, thanks for the great video. What reed valve do you recommend for a 77 rd 400. The original ones seem too small to me. But maybe l am wrong. I am thinking of putting 32 mm carbs on also. Someone mentioned yz85 reed valves or rz350, with reeds spacers and opening the intake to be able to make them fit. Do you think getting one of these ones or just getting carbon fiber or another material reeds for the stock ones. Could you please let me know what will work better for more power. Cheers
This engine uses 30 mm carbs, stock reed valves and fiberglass reeds. I tried big valves and carbs but it didn't make more power. Many racers go big but few have dyno'd back to back as I have.
sweet !!!!!!!!!!!!!! ..........................just sayin ...........................:)
fucking brilliant
God knows how you balanced the pipe to do the last section 😁
Masya Allah...like that bike
I realy cocked up putting the two ha.fs of the crank casings together the two inner crank bearing moved so the locations pins weren't in place as I tightened it up it cracked the 2 bearing
You know what I'm sorry it happened it sure is a gross mistake as you shouldn't bolt down a part that's not join together with the mating surfaces tight and try to force it with the bolts. The crankcase is now warped aswel.
If you can get ahold of TZ750 pistons these bore out to 440cc
Can I use the same porting timings on a 350 ? Or are they different?
Thank you for this cool informativ video :)
Port timing as measured in degrees are the same, but expansion chambers will be different.
@@stanlipert8513 thank you, that’s what I thought. 👍🏻👍🏻
Those port timings you gave were they standard?
Or were they your new figures? 126 196 . . . I was told the magic happens at 60 degrees apart e.g130 190
35 degree blow down you have here. . Wow she going to rev then.
Not standard port timings. You can see the marker lines on how much the ports are changed. This is full race but kept to a reasonable redline RPM and compression. Thanks for asking.
@@stanlipert8513 I love your work. My dream
@@stanlipert8513 do you lose bottom end power with your tune? Does it shift the power higher up in the ranges?
@@coco-te1op A little loss in low RPM power, but this tune has a low 9500 RPM redline, best for racing on the track. More power is available for a shorter crankshaft life.
where are you. i have one of these and a 350. i need some help.
65 HP on electronic ignition . chambers look similar configuration to Spec II. God that bikes sounds exactly like my 350 resto mod. What about Dave F carbs; Bigger V Force reeds and UFOs and boost bottle .
Dave F carb mods were a replica of R5 specs. The stock RD400 carb bodies take the mods well as are shown in this carb build. I have dyno tested Big RZ reed cages and boost bottles. At this restricted RPM range, there was minimal or no gains. Don't believe the hype.
UFO are excellent for round slide carbs, not needed for PWK flat slide carbs. Racing an air cooled two stroke, UFO's are good for four strokes, not necessary for two stroke. You can ride around the mid range.
R5 piston ported ? RD has reed cage ? So The R5 wakes up 5 up RD little sooner. Had a friend owned a Daytona Special all stock. I 74 H2 with every goodie made back then. I racked 2000 of tickets in 2 months on sketchy fun as F machine I bought off a one line classifieds add before the net.for 450.00 I need a smoker.
Para que el soplete 🤔
Oh, just looked at my playback speed 2x ... heh heh.
Playback faster if you wish!!
Hello sir, did u ever check individual weight of each flywheel of rd 350 B crank shaft. It has 4 pieces . Shoudnt both cranks which are timed at 180 deg angle have equal weights . Need info from you and anyone who has it on this channel. Thanks.
There will always be rocking couple, this is why the RD400 engine is rubber mounted. Live with it.
@@stanlipert8513 thanks sir...
But in india the rd 350 that were sold were not rubber mounted....yet i hv ridden many that have practically no vibrations. Frankly till about 100 km /hr ....never tried going beyond cos of utterly useless hopeless indian traffic common sense. But the question still remains....what should b the weight of the 4 individual parts and both the sub cranks that make up the main crank. It will b an honor if u could ask in your circle of friends and help me out . Thanks again.😎
Vakwerk 👌👌👍
Hi bro I’m Gopal contacting from India any Social media link to get in touch with you ?
I own a Yamaha RD 350,
Regarding the bike
Thank you
Sir, if you want to sell it. Please let me know.
I won an rd400g and restored it, it took 8 years…. Also accumulated a ton of spares, I have two spare engines and a frame, I’m thinking about doing a track bike out of those…. My skills are far from yours so probably let a pro do the porting.
Can I run a rd400 crank and cylinder on a rd350
No, the 350 and 400 have different strokes.
Nope. Wouldn't be an improvement even if they did fit.
Invest in handling upgrades first is my advice.
@stanlipert8513 Meaning the deck height from center crank case is different?
@@homie3461 .... Yes , the cyl. stud spacing is identical on all the air cooled models, ..... however the studs are LONGER in the 350 cc engines and MUST be used if running a 250 bottom end.
@@homie3461 There may be small discrepancies in the matching between crankcases and cylinders, ....... easily matched with a little work with grinders or hand filing . ...... have fun, BUT don't go too far, .... its easy to remove a bit more metal , ....but much harder to replace it !
He visto restauraciones de otras motos y se ve al detalle todo lo que hacen, en este vídeo hay detalles que no se ven o bien por el ángulo o bien porque las manos del operario no lo dejan ver. 👎🏾
Show me your video...???
Yamaha RX please reduction🙏🙏
Sorry, there are no RX in USA. The same techniques can be used. Research what other tuners have done first. Cheers, Stan.
Find urself some power jet carbs
My first setup was with Keihin PWK
with power jet, the best 2-twostroke carbs. As a vintage/classic race bike , one has to follow the club rules....
I see now why no Vforce reeds or flat slide carbs