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Air leak

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blckrevo33

blckrevo33

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  1. Bashing
Ok so, i finally got out today to retune the revo after sealing the motor. once it warmed up it ran awesome off the line,wheelie on comand and everything.Then when i started to make high speed runs it would go to shift into 2nd and bog right down and wouldnt shift.So when i went to shut it down by blocking the exhaust it kept running.I am thinking another air leak.I sealed the backplate and carb,so i doubt its leaking from those points. the engine has about a half gallon through it.Could it be a bearing leaking this new in its life?Also the coupler from the header to the pipe is not leaking,that was the first thing i checked.Could sealing it send the tune way off to the point of making it seem like an air leak? Any suggestions?
 
It sounds like your high speed needle is slightly out of tune, more than likely just slightly lean. Try richening it 1/16 of a turn at a time make a high speed run continue until you are getting into 2nd with no bogging. Do not plug your exhaust to shut the engine down, that puts a heavy load on the engine and can cause the connecting rod to bend or break. Pinch the fuel line off the shut the engine down. Yes that does cause a lean condition but at idle and for the short time period that it is lean it does not cause measurable or even significant damage to the engine. if you have an air leak your engine would idle high and run poorly, if you want to do a quick check for an air leak get a spray bottle and fill it with rubbing alcohol (label the bottle so there are no accidents) get your engine running while the engine is at idle spray the alcohol around the front bearing, carb base, head, and backing plate if your engine rpm suddenly goes up you have an air leak in that area. Be aware though you can get a false reading if you get the alcohol in the throat of the carb.
 
Thanks for the advise. i did richen the hsn 2 full turns and it would shift into second,but when i had it like that it would idle real eraticaly, high idle then no idle at all. tomorrow i am gonna put the needles back to factory and give it the alcohol air leak test and see what happens from there. normally i do shut it down by pinching the feul line but i was in a hurry to shut it down because the idle was screaming highand i wanted to shut it down in a hurry. but now that you mention the damage it can cause i wont be in that much of a hurry lol.
 
Well with an erratic idle you just might have an air leak, or a fuel supply issue or your low speed needle could be out of adjustment.
 
ok i can't take it anymore i'm gonna go give it the leak check now. i just went outside and found out the neighbors are gone for the weekend!!! so i will be updating in a few.

Thanks maxxheadroom checking the needles and fuel line. thanks for that one i completely overlooked checkin the feul line.

Well upon closer inspection i found the air leak!!! it was the feul tank lid o ring it was missing a big chunk in the back. replaced it and started at factory settings and DAMN!!!!! it rips now!!!shifts great and idles like a champ.thanks again.
 
Ah man I completely forgot about the fuel tank, good find that will certainly cause a lean high speed condition!
 

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