Engine cutting out at high rpm By dozer187 (Read 7,869 times)

[Alleyoop]

If one of the lines attached to the AIR BOX is the VALVE COVER VENT that one has to VENT so zip tie it high on the frame higher than the valve cover. What other hoses are connected to the AIR BOX? Only two other things I can think of is you have some emissions and 1 would be the EVAP system and 2 a EGR system. Pictures of hoses and any canisters will tell what emissions if any you have on the scoot.


scooterdoc.proboards.com/thread/9153

[Alleyoop]

One other thing you can test out, plug in the old CDI you could have a bad CDI.

[dozer187]

i think there is only one line into the stock air setup, and my cdis are both fine, i tested the bike with the stock airbox open with no filter in it and it revs up fine past 8k as soon as even just the cover goes back on it bogs just below 8k so its def an airflow issue

[Alleyoop]

Great, your on your way now that you know it's a Fuel Ratio Mixture problem, in your case to much fuel and not enough air on the top end.
Alleyoop

[cyborg]

bingo!!!!!

[dozer187]

got the new filter on there and now shes running lean lol i cant catch a break with this thing, gota wait for my new 95 jet to come in now as my 90 isnt cutting it... do they make 92 jets? and where would i find one if they do, all ive been seeing is 90 and 95

[dozer187]

ok so now i have my new filter on there a manual fuel shutoff in place of the stock vacuum setup as it was failing, so now i cant get the thing fine tuned the 90 jet is to lean the 95 bogs anything higher than 1/4 throttle, im assuming the 95 is to rich?

[Alleyoop]

Dec 19, 2015 19:28:08 GMT -6 dozer187 said:

ok so now i have my new filter on there a manual fuel shutoff in place of the stock vacuum setup as it was failing, so now i cant get the thing fine tuned the 90 jet is to lean the 95 bogs anything higher than 1/4 throttle, im assuming the 95 is to rich?

If it is bogging at 1/4 throttle YOU HAVE AN AIR LEAK, and I since you took off the VACUUM OPERATED PETCOCK you may not have plugged up the Vacuum line going to it.

What your describing would not happen at 1/4 throttle, has nothing to do with a MAIN JET.

[dozer187]

i dbl checked the vacuum cap tightened the ziptie i have on it, not boggin at 1/4 ne more. now just around top end again, i think the 95 is to rich and the 90 to lean

[Alleyoop]

What do you mean YOU THINK the 95 is to RICH and the 90 to LEAN? Find out which it is RICH OR LEAN i told you how to determine what the motor needs. Then if the 90 is to lean and the 95 to rich then get something in between a 92 or 93 or both.
www.quickfueltechnology.com/carb-components/metering-blocks-and-components/gas-main-jets-1.html

[dozer187]

shoulda rephrased, 90 is def to lean, the 95 is doing what it did b4 i got the air filter, let off throttle at full and just stays. thanks for the link ive been trying to find somewhere that had inbetween sized jets

[dozer187]

so after about 6 hours of working on and testing this bike im at wits end, ive run everything from an 88 to a 98 size jet and nothing runs right on top end. have a new plug in there, no airleaks, and 3 different perfectly working cdis and still cant sort out this problem.

[Alleyoop]

What exactly is it doing at Wide Open Throttle? Any motor sounds or what is happening?
Alleyoop

[dozer187]

it sounds normal up to the point that it cuts out then it sounds like a rev limiter on a car, problem is its nowhere near the actual rev limit of the motor, it does it under load and with the rear wheel off the ground. im still running a stock exhaust im wondering if that could be part of the problem

[Alleyoop]

That could do it the Mufflers that come with the scoots are very restrictive to make them quiet. Run it one time without the muffler and see if it solves the problem.