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carb half open?

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F

fasterdenu

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my buddy that introduced me to nitro rc's has been having this problem that none of us can get figured out... Grudge and i went to his house yesterday to run on his track and we ended up having a blast but my buddy (we call him Kaz) still can't get this figured out...

the only way his revo will run and idle is with the carb half open, the rpms sound normal, the clutch isnt dragging or anything, weird cuz you have to have the carb halfway open, but the rpms dont represent a normal carb being at half throttle... we even tried a different carb, and while the problem improved, its still not right

its a stock 3.3 mill, trinity pipe, motor saver filter...

once he could get it to run, the power it produced seemed normal, temps were fine, the only problem he really experienced was not being able to use the brakes... we centered the servo, adjusted the linkage, etc, pretty much everything we could think of... the idle screw is all the way in and the slide is no where near resting on it when it will finally idle...

any ideas?.... we are totally stumped :\
 
Sounds like a bad casting or your tuned far too lean. Wrong idle screw maybe? Although, you said it was the same with a different carb... I'd send it to traxxas and ask them to sort it out. Worst they can do is send it back... knowing them though, as long as it wasn't abused, they may end up giving you a new engine.
 
i needed to add that this engine was the original 3.3 from when the revo was purchased new, and it was rebuilt with a new piston and sleeve once.... the problem has been since the break in procedure was done on the new piston and sleeve.... throughout the break in, the motor ran normal... he has tried different pipes... buku, single chamber resonator and trinity... buku exaggerates the problem, trinity seems to improve it somewhat, but best results are with resonator

thanks for the help so far guys...
 
I'd pull it back apart and inspect it. Maybe the sleeve was put in crooked or the piston put in backwards or a head shim was forgotten... any of those could give you weird issues.
 

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