Yamaha XS1100 Cafe Racer Project - Episode 51 - CV Carbs & Pods v Velocity Stacks and Airbox
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- Опубликовано: 6 окт 2024
- A look at air intake options to help make an informed decision on what is right for you. Pod filters, velocity stacks or factory airbox.
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Perhaps the best educational motorcycle channel on RUclips
I've been working as a mechanic for a few years and have only recently gotten into performance tuning and moding bikes. I have a good understanding as to what it would take to bulster performance, but this was so informative and hit a lot of points I would never have really thought of! Thank you so much!
As always... excellent in depth detailed knowledge in how to make your own trail where others may follow. Thank you.
Great show Andy. (again!) Personally, the chromed shape of the air box enhances my attraction to the xs's beautiful lines. If only one could marry the air box to the flatslides....
Great work Andy, you always seem to make everything so interesting, and I find myself totally absorbed in your videos, well done mate.
Awe...shucks. Thanks mate
Love that can do Aussie attitude, thanks for the lesson and encouragement.
Cheers David
Very good. Excellent. I don't like multis, especially in line 4's, but my god, your XS1100 just sounds gorgeous! Congrats.
Excellent explanation mate, also reminds me of why I miss Australia so much (spent some time there in 2001 and wish I could have stayed, sadly never made it back, maybe one day) I feel you on the hoarseness, spent over 18 months croaking and only recently my voice is mainly back.
Weighing my options up for the Gpz I'm working on currently
I found that my cv carbs on my xs400 worked better with the stock inlet rubbers with spaces on the end to mount the pods. If you put the pods straight on the carbs the pressure wave would hit the back of the pod filter and return to the carb to soon and upset the carburetion.
Rd250lc two-stroke was the same, it needed 3-4in spaces between the carb and the filter.
THAT IS CORRECT! THE US NAVY FLOODS ITS AIRCRAFT CARRIERS WITH SMOKE SO AS TO DISPLACE OXEGEN AND FIRE SINCE WW2 WORKS GREAT EVEN A GINT SCALE YOU DAD WAS A SMART GUY
EXCELLANT AS ALWAYS
Hi Andy another great vid, i love to watch them as I pick up a few things but more it brings it back (the memories especially on the XS). I didn't mess with the air filters on my bike but my bro did on his. He was a great believer in staying close to standard unless changing a lot of stuff for the reason the manufacturers were not far wrong though also new restrictions for emission laws.
I will try recall, the velocity stacks he modified by shortening them and fixing bell mouths to them though still in the standard air box, the air box he removed the inlet tube and made the opening much bigger, he also diverted the crankcase breather though to atmosphere behind the back wheel (Triumph) and fitted a K&N air filter, It still looked standard, I know it had great mid range and at at around 70mph top gear roll on I had to notch it down a gear or two to try stay with him. Before doing the mods though simple he did do a lot of calculations ( he was petty smart)
When he was a student and mid term working for the council doing a garage clear out he was given a bottle of Mercury, about a litre. He then got glass tube from a medical suppliers plastic tube and carb adapters for the intake manifolds, my old man made, he clipped the glass tubes to a bit of old pallet with wire with the bottoms going into the cut off bottom of a fairy liquid bottle 1/2 filled with mercury, with the plastic hoses on the end of the glass tubes going to the manifold adapters and he was balancing carbs. This was 1977 and it was on a 75 Gold Wing, and the smoothest Gold Wing you ever heard the 2 Honda main dealers in Belfast at the time or any other marques didn't have vacuum gauges then.
I still have the remnants of them somewhere and about 1/4 litre of mercury. A friend of his spilt the mercury over his garage floor and instead of brushing it into a pile where it would have come together he brushed down the drain.
Sorry for going on a bit been enjoying the vids on the carbs.
Mercury down the drain? That can't be good.
@@ANDY5 I know idiot.
This is the first video of yours that I saw. Liked it and learned so much, I started at the beginning with Basketcase, now here I am again. Also learned about the pitfalls of Delboy from you and Matt as a result. RUclips had coughed up a random video (you know, with those new algorithms they just started using) and the guy was talking carburetors and mentioned velocity stacks. I was very familiar with carbs, but had never heard of velocity stacks, so I googled that, and found this video. Hooked ever since. Also love the K&N video BTW. I used to be a Delboy fan, but not a fanboy, and now I'm done, after his 'depression' comment. Possibly more to come on that, stay tuned. Keep up the great work!
Awesome video and a lot to think about. To your point about the length of the stock rubber stacks being optimized to reduce noise first and foremost.... I'm not so sure about that. Intake tract length tuning has a *LOT* to do with velocity of the charge and you get into some crazy stuff with resonance and "sonic" tuning. Long runners (traditionally) imply a stronger low-mid range response. So in addition to the priorities regarding thorough filtration and noise regulation, I think the factory air boxes are tuned for optimal smooth low-mid range response. Seems like most of the shorter "racy" velocity stacks and pod filters prioritize high rpm performance for the race track or drag strip, to the detriment of linear response on the street. I have an XS1100E as well, with a stock airbox and RC-Engineering 4-1 pipe with a baffle and my favorite part of the bike is the very strong "roll-on" mid range response. Wonderful touring bike for burning up fast miles on in comfort.
You are the man. Thanks for doing what you do.
fantastic video with tons of great information. Thanks for the contribution
Great chat thank you!
Hey mate, love your work on here mate, nice to see some Aussie blokes getting the info out there.
Anyway, I’m building a cafe inspired 87 CBR600F1 and want to run pods however to add to all the other pod related issues I can’t understand how to attach a pod to the flat faced carbs, they have no “nozzle” the flat intake side just attaches directly to the base plate for the stock air box.
I’m assuming I’d have to fab up a nozzle that can be bolted down to the flat side of the carb but is there another way?
Hope that makes sense
Cheers,
Daniel
Now this I'd like to see! Those old Hurricanes really responded to rejetting, pods, etc. My '89 had a rack of CR flatslides and full exhaust, kept up with F3s no problem.
A mate had a Lotus 7 with a little 4 cylinder engine with possibly a fair bit of cam overlap. The carbs were a pair of Weber 40DCOEs, without the longish stacks on the carbs the fuel consumption was dire, we thought it was due to "stand off" of a cloud of fuel just outside of the carb. Unlike the bike the air blew across the carbs (no airbox and engine round the other way).
I found a good compromise between stacks and pods on my xs1100. I took the original rubber stacks, and squeezed them inside some oversize UNI pods. Runs much better than pods alone!
Hi JJ, thanks for the comments. I did mention that option at one point, but I think I said to try and fit the conical pod type, same outcome. Andy
Oh, I missed that part in the video. The long UNIs are nice, as you can completely hide the rubber stack within it, with plenty of room on the end for breathing. You just have to remove the spring that is usually inside the UNI. You can see them installed here: i.imgur.com/tsNMNrO.jpg
Air intake manifold on a fj1100 fitted to the xjr big difference, they line up better with the casting of the head
So after thinking I've decided I'm gonna use velocity stacks. I thought about using the pods but after seeing the rubber and how it blocked certain things also thought about using the factory airbox but well its a pain to remove and install. 1979 Yamaha XS750 Special
here in the US I run 95 octane on my Triumph twin engine with the CVK with K&N pods and it runs better than it ever did from stock with the airbox with a completely open exhaust. I run 152.5 main jets and 42 slow jets with a .5mm shim on the needle. I did all of this on my own and I have never in my life adjusted or even opened carbs. I just wasnt willing to pay someone a couple hundred dollars to do it and it never run like I want and then after all that money and time I still wouldn't know how to do it.
Those pod filters you have there Andy are shocking, I ordered a set of those, threw them out, that lip blocks up the air intake ports on the carbs.
Found a pair, exact copies of a K and n no lips very reasonably priced, got a pair on my CBX, Yamaha xjr, and will put a set on the GS vm33 smoothbores
Brilliant, thank you for explaining it
I've got an aftermarket AIR-BOX on my '82 CB900F (aka "CB900K0 Bol Bomber" check it out sometime) This new "air-box" is made by "DIMO" from Fiberglass - Thing is, it's really only a plenum it doesn't have a filter element - So what I'm hoping to do is EXTEND the thing, to make a really big lightweight air-box, more volume a bigger filter and hopefully not too heavy. Got some ABS sheet, but I'm also considering using more Fiberglass for the additional sections. The PLAN is to set this all up with some Keihin round-slides, CR29's or CR31's perhaps - it's a 985cc big-bore, or so I gather - I didn't rebuild it myself, though it is definitely a rebuilt engine. I bought the bike with K&N pods on the stock CV carbs, but hadn't even made a mental note of that, 'cause I was so turned on by the WOLFE pipe and the CAL-FAB swing-arm, the Tarozzi rear-sets & fork-brace etc etc. So - thing is I NOTICED the pods-vs-CV's thing without LOOKING at 'em - It was when I was RIDING the bike, I felt a lag in the low mid-range, and this being my first CB900F it didn't feel as hot as my old '82 CB750F (two of 'em actually) So YEAH - there had to be something wrong! It could only be explained by the inlet side when there's such a hot pipe on the exhaust side - Right? So YEAH - I don't even HAVE a factory air-box, I had to replace it, but thought if I'm gonna spend the $$$'s doing THAT, I might as well go "whole-hog" and do it "PROPERLY" ha-ha. BIt off a bit more than I can chew? Guess we'll see. WISH ME LUCK! Ha-ha.
+SoyBoySigh sounds like you're all over it mate 👍 I will check out your bike, thanks for tuning in.
Well thanks for the kind words, and do check out the bike - just keep in mind that it's a "work in progress" ha-ha. I'm "SoyBoySigh" on the bike forums, and "Binky Sigh" on Facebook, which seems to be the last place to view pics anymore thanks to the Botophucket meltdown. Hopefully it'll all come together soon, this winter I suppose. Our short riding season here in Alberta Canada gives plenty of time to work in the off-season, that is IF you're able to bring the bike indoors for the winter!
Even the distance the carbs are spaced from the heads make a difference, a bit here a bit there all ads up, when you look again 10 hp
Yes intake tract length is critical
Hi and like your show, I want to run air filter pods on my Ducati900cr, and maybe velocity stacks for track day. Can you tell me what size filters and velocity stack will fit the stock carbs?
I plane on switching to FCR carbs when I can afford them.
What about fabricating a better looking air box? Or would you still be looking at something the same kind of size at a stock one? Also I guess the carbs would likely still need re jetting
I just learned a ridiculous amount of information from this video... Holy crap. One question about that air joint you mentioned though. If you eliminate the stock air box, could you replace that air joint with a straight line? Or should you just leave the T joint and flip it down like you mentioned?
Thanks for this video, and this channel!
Just point the tee down, don’t add extra hose.
Hey Andy: do you think you can do a video on valve adjustments when one of your bikes needs it? Thanks and another very informative video!
Hi Miller, episode 15 shows how to re-shim the valves for clearance (lash) If you are talking about camshaft timing I am planning to do one soon. Andy
+Andy's Motorcycle Obsessions I must have missed that episode. I'll go back and watch. Thanks!
Hi Andy great video. I have a friends, bike that l have brought back from the dead for him. I will not bore you with the detail but in sort, he had started a cafe racer look and had chopped lots of wires and hoses and removed lots of hardware. I have fixed all the wiring and sorted out all the hoses. The carby was also a mess, pulled it completely apart cleaned and serviced. Bike runs well when stationary revs and good throttle response. Set timing, vacuum lines, new fuel lines and filters. Taps set to prime, air pods off. Carbies synced and all seems good. But when l take it for a road test bike pulls very strong up till aprox 5k and then Boggs down. I assume it's a jetting problem but not sure here to start. I am in Victoria and would greatly appreciate any advice.
G’day mate, what type of bike is it?
It’s a 1979 XS1100
Hi Andy- thank you for all the guidance in this series, your notepad sessions in other videos have taught me so much. I'm working on a 1981 xs1100 that i bought as a rolling chassis. I'm really just trying to get it back together enough to make a no-comprises bobber. I am a big fan of the look of the velocity stacks, and would love to run them on my project. Do you remember where you sourced your set? Any thoughts on running them with Ramair sock filters on occasion?
It's your engine mate, do what you want. I have a set of Ramair twin stack filters that I have had on there from time to time. Mostly I use my K&N oval pods.
@@ANDY5 I picked up a set of velocity stacks from dime city cycles. I'm going to give them a shot, just have to conquer the electrical system first. Your wiring videos have been a huge help. Thanks again.
It's strange when people and professionals do not recommend porting &/or polishing intakes and promote a rough intake surface is needed as "...the air has to tumble into the combustion chamber...which improves air flow...". I've been seeing this contradiction of airflow dynamics for a very long time, in this sense, velocity stacks help with airflow direction and volume, stopping the tumbling of air into the combustion chamber. This contradiction is apparent in certain car magazines here in Australia and is seen on a couple of YT videos about intakes. It makes perfect sense that the velocity stack improves airflow/volume quality, so would these people hawk that porting and polishing does not apply to the same aspect of airflow/volume dynamics?
Because it’s on the other side of the carburetor. Once you atomise fuel with the air you want to start swirling it around to help keep the fuel in suspension. Exhaust ports however can be like glass. As for porting intakes there is definitely o issue there, many improvements opportunities can be lurking in a factory intake port. Thanks for watching mate, Andy
Is there any difference between tumbling and swirling? Same horse different Jockey? I can see the swirling effect is more suitable for intakes due to the induction resonance of a running engines intake, volumetric efficiency, and that fuel/air mixture likes to bounce off smooth objects rather than rough surfaces. It makes perfect sense to me that rough surfaces produce more than a residual loss in the swirling and resonance effects, in the same way sound waves dissipate with multiple objects in it's line of travel. I wonder if the velocity stacks help counter much of this loss off resonance and swirling because of the mini supercharge they produce?
That’s the theory, getting the correct intake tract length for the pulse you want at the RPM you want is where the science lays, and flys straight over my head
I like a smooth entry lol.
vent your crank through a filter, i don't fancy dirt in my crankcase
While the factory airbox might be big, clunky, and less than sexy I think they provide the utmost protection in making sure clean air goes through those carbs. I don't underestimate Japanese research and development quality. If they put it on the bike, then I'm sure they spent many hours running tests. Whenever I see pod filters, I wonder how they prevent rain from eventually getting sucked in. I think we've all been stuck in torrential downpours at one time or another. I also have to do some riding on Midwest USA rural gravel roads that can produce choking clouds of dust. My factory airbox is staying in place.
Horses for courses mate. I 100% agree with what you say. The factory airbox is your best option for stock carbs and ultimate protection, like I said, engine wear is X 4 with pods. BUT, if you want the look you can get CV's to run. Can you get them to perform? Probably not. If you want performance you have to do what I did and shell out $$$ for race carbs. A lot of guys make the mistake of cutting the mounts for the air box off the frame, finding they can't get the bike to run, and then can't go back. They get disparaged and end up walking away from the project. Investing in another set of carbs would see them smile all the way down the road.
Hi Andy. Is it an illusion or is your right clip on shorter that the left one?
Andy what's your opinion on the Ramflo 400 filters? Same potential jetting issues as with the pods?? Cheers
Awesome video! This video helped me a lot!
Hey andy how does the exhaust come into play with tuning the carbs aswell? I heard around the bush about back pressure and flow?
I'm new to all this and just finished top end rebuild of a Suzuki X7! Lots of smoke and ting haha
G'day mate, thanks for tuning in. exhaust will impact jetting as well. back pressure is not an issue on bike engines so if anyone tells you it is you should ignore what they said, and anything they say following. I have a straight through 4 into 1 on my XS and no baffles in my Ducati. the best place to start if you have intake and exhaust mods is two and a half sizes up on the main jet and lift the needle one position. you will need to be sure it's not leaning out so run it at above half throttle for 20 sec and hit the kill switch, then check your plugs. if you need to wind your mixture screw out more than three turns you will need a larger pilot jet, or if you go up three sizes on the mains. Hope this helps, Andy
+Andy's Motorcycle Obsessions
Thanks Andy!
Being two stroke is anything else I should worry about?
Oh crap!! Exhaust id HUGE on two strokes. As long as you retain the expansion chamber the muffler won't make a lot of difference. Ignore what I said about the jets now. What type of bike is it mate?
Hahaha it's all good should of established that earlier.
It's a 78 Suzuki GT250 X7 it's got stock exhausts which have expansions on them, I've got pods on it and it's running ok. I've currently got 107 mains and once size up pilot (can't remember the pilot size) coming up from std 87.5 mains. Right now riding with the needle clip to the very top and it's pretty responsive. Yeah I can't afford microns or all speed chambers so wanted to take the muffler out just for more TING hahaha
Oh, cool, they are an awesome old bike. Mate you want to be careful when mucking about with two strokes, they will lean out and melt pistons much quicker than a four stroke. Also your fuel/air mix goes into your crankcase so filters are more important too. Enjoy your ride mate, keep her safe and upright, and thanks for tuning in, Andy.
I think if I'm correct you have a set on the xs
K&N oval. Yes they are a cheap and crappy set of pods and they do impede the air correction jets
I wish you were my neighbor. We'd be buds
Thanks too much for me
Does flatside mean Mikuni?
No, Mikuni is a brand, flat slide is a design type. My flat slides happen to be Mikuni RS36’s.
Andy's Motorcycle Obsessions Thanks. I’m an Aussie in Japan. Have a W650 and put pods and a sweet custom made titanium two into one exhaust made for it. And my bike rides like a dog most of the time. Here is the thing. It is not consistent. Some days it will pull and other days it just splutters and coughs and is almost unridable. Almost at the point of giving up, I saw your video and it has been a hugely significant learner for me. So now I am thinking that maybe a flat slide carb like a Mikuni might be better. I assume I have the ‘other’ ones. Local mechanics don’t really seem enthusiastic about helping this strange foreign guy with such a pesky task as to tune his carbs. I will suggest your,’rule of thumb’ but every-time I suggest something I feel I just scare them away even more. Standard air box long ago ditched. I couldn’t tour this summer it was so bad.
Tommy my advice is to contact Mikuni, they are a Japanese company so it shouldn’t be too hard. Ask them what carburetor they recommend for your specific setup. I have found that they are very good, at least Mikunioz are, and the recommended carbs are almost always plug and play. That’s what I would do.
@@ANDY5 Thanks. Reason is, u mentioned flat slide carbs are easier to deal with pods etc. I also saw a dude on a KZ900 with Mikunis modded onto his bike and he said they were great. No doubt they cost a fortune, but I wanna ride the thing and the two into one I had especially made. (Not knowing if would be a dog!)
You should have been a teacher mate
My xj was absolute nigthmare to get working on pods......Well it was easy to make it run..cinda..... but to make it perform..... oh lord jesus it was slooooooow process..... well i got it to perform but not perfect BUT there is BIG problem whit the pods that confuced me when i was tuning the carbs..... Well i ride everyday in all weathter, in winter whit small bike so, 1 and 4 pods get more shit to them.... and that fucks up the tune..... so i did big mistake for going on pods, they dont fit my ridin style what is all year in every weather, spend too much money on tuning because the problem whit 1 and 4 pods getting more shit on them and i didnt realize it at first.... then i was like oh i just buy original airbox......well i cant because it wont fit anymore..... how about custom airbox.....well yeah but didnt have money and time for that.....then assload of more small things started to come and i just said fuck it and sold the bike....... Alot learned from that bike and now i know better..... But hey who said learning is free :D
+TT GarageRat sorry to hear it didn't end well mate. Yes a daily ride is not the bike to make these mods on. You're right about the outside carbs, they also get cooler air than the inside carbs which can screw things up. Andy
So basically, the success of a bike running well on pods would be greater on a 4 stroke, 2 cylinder bike?
I went to sleep.
+Mark Walters thanks for tuning in. Sadly not everyone has the required attention span, but thanks for trying 😊 Andy
Andy's Motorcycle Obsessions
Andy I tuned in with the best of intentions. What attracted me was the SX 1100. I bought a used one in about 89. I'm not a mechanic and to tell you the truth I didn't know it was a tutorial. I still gave you a thumbs up as I do to almost everyone who is at least out there doing something for the world.
+Mark Walters thanks mate, most of my videos are about the build. there are some ride vids so check them out. Thanks again, Andy
+Andy's Motorcycle Obsessions saw a CBX parked the other day at the Veterans Hospital. Beautiful but the tank was in original condition. Hey Nick or two and rushed otherwise really nice. Wasn't smart enough to take a picture and when I came back it was gone.
Can also put a foam filter over your stacks and it looks good like a racing kart engine thing to me. That's my plan.