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HELP 472 supercub jetting, tried everything but still nuthin!


bansheeboie

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472 supercub,vf3,35pwk air strykers,k&n pods,sea level,pump gas,+5 timing,30-50 degrees,BB inframe shearers. Current jetting is 155main,48pilot,cel needle mid clip. I don't think a supercub jetting shud be that small on the main IMO

 

This is what my plugs look like(has oil on tip/wet)

25332F6A-C87C-4235-9227-8F94DB400B02-499

58D4C1A2-1BA8-4D9B-A6CA-9CB7A045D64C-499

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I'm going to say that with the motor only running 35's your getting a VERY strong intake pulse. (I had this issue with a 472 Cheetah) Your motor is sucking SO HARD thru the carbs that the jet is flowing a lot more fuel than if you had bigger carbs.

Your jetting will need to be crazy lean compared to what you think it should be. (142 mains and even 35 pilots) But don't just jump down that low....work your way down to a happy combo. Or get some 39's like most would run and your jetting numbers will match everyone else's usual jetting.

 

But I think the issue is the Air Strikers in a 35mm.

39PWK's would be what most would run for that motor

Plus those pods are robbing air flow and costing you 2-3 HP. Get the longer filters if you buy 39's. 

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Ok I got 39 pwk's I'm about to order some intakes for them NOW! Lol

Yeah, way better move than chasing jetting on carbs that are just too small for that motor. 

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ha ha  good choice...  

 

make sure your ignition and rest of the motor is 100%.  check resistances on the plug caps, thoguh the coil itself and even do ground drops to ensure all your grounds are solid.  make sure you have a strong ( preferably stock oem) stator and the pulse is spaced correctly and your flywheel isnt damaged at all....   just a few things to check..  

 

i have ran stock banshee carbs on 421 cubs'   the usual mains i end up with were 410-430's...    i have ran down to 145's on similar builds with 35mm pwk's/.   the larger motor will like the 39's better tho..

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If it's not a ported cylinder you might be just fine with the jetting (The motor will be around 68 to 78 HP depending on your pipe choice) So the motor might not be breathing hard enough to have the excessive intake pulse that can cause the drastic suction on the jetting circuits that I was describing. 

But the 492 cheetah I had was fully ported with custom domes and I even had my 35's taper bored to 37's and the jetting needed to be VERY small due to the amount to fuel that would get pulled thru those jets.

We had the same issue with the 485 "Nickisgod" had that F.A.S.T ported. He was running 38 Air strikers. But again....Those were fully build motors. If your machine is happy with the jetting you have, don't let anyone talk you out of what works for you. Stay happy with what you have and be glad it's working. 

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Well, I'm ported by wildcard racing, 19cc domes cut by Titan Racing. My motor is BigRed350's old 485pv setup. Running Vito's fat bastard pipes, c12 and klotz r50 40:1.

 

Nick made like 95hp on his setup. Maybe I should buy his carbs off him.

 Yes he did. I dyno'd it. LOL.

So you got Big Red's old motor. Congrats. I advised him to have Tim cut those domes because the standard ones Trinity sends are detonation prone. He always said he was very happy with that motor. Plus like you said, it is ported, so it will be making more power. 

If your happy with it and the plugs look good...stick with that. Just about everyone I talked to advised 39's but they also said the 35's were only hurting the peak number by maybe 5 HP. If your not duning or full dragging.....I might not be worth the money and effort to switch.

 

What kind of riding do you do with it? Where?

Any thoughts of making a road trip out towards the Michigan dunes some time?

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