My 05 750 when I start it up its fine, but if I let it set for a bit at idel the it fluctuates between 500 and 1000+ RPMS sounds like it burping. When I rev it it sounds like it is choked up, and just sounds bad. I just put a Micron exhaust on it and a K&N air filter. I dont have the upper fairings on it because I need a new one (cracked the old one) so I dont have the Ram Air intakes on it.. could this be a problem? or is it a bigger problem?

 

It could be, but it almost sounds like you forgot to hook something up. There was a guy that had Gixxer 6 that forgot some vacuum tube or something of that nature once, and it countered the problem by pouring tons of fuel in, running so rich anytime he let off the gas at a mid-RPM range it'd light a fire coming out his exhaust(And only getting 80 miles to a tank). So in short, check all wiring and hoses first, I don't see a reason why lack of ram-intake tubes would do when it's sitting still anyways.

 

with a pipe and a filter....have u put a power commander on it yet??....what does it sound like on the decel?....if it is popping a lil that is ok.....if it is whining like a 2smoker on the way back down...its too lean...

 

no power commander yet... it just sounds choked as hell

 

a choked sound is usually a higher rev..thats all...so i know that your bike is FI....no choke lever....so u could be running lean causing your idle to be higher....too much air and not enough fuel....what color has your pipe turned from the heat??

 

Take out the K & N and see if it stops. I used to run K & N's but they made almost every bike I rode run like garbage. Most mechanics around here say the same thing.

Try putting in the stock/old filter if you still have it and see what happens. Shouldn't matter with the tubes off, I had mine off for a while and it ran fine.

 

ok... just went out to the garage and tried it no difference

 

All my parts came in today so I will put the ram air tubes back on and see if it makes any difference

 

also Im running Elf racing fuel in it could that cause the problem?

 

I run jet fuel in my bike an it dose make it sound funny, it will rev funny also, watch how long you run it because your bike will get hooked like mine, can not run anything else with out it feeling like it is going to cut off or it has no power. Are you running half and half or st8 race jet fuel?

 

40% race fuels 60% 93 ethnol

 

+1 i forgot to put a vaccum hose on once and it was running really rich and spitting unburnt fuel out of the pipe blah blah blah. got home and thought i would change the plugs and found the hose.

 

The exhaust does smell extra gasy

 

Yeah it can be the fuel mine is 105 and the factory told me any thing higher will burn the motor up. The smell dose stink so that is normal. Like I said my bike got trained on it, so it was like crack and ran like **** with out it. It is ok the way you are running it because you are mixing it, my bike is carbarated and yours in FI right? May be a big diffrence, I have heard of something happeing to the injecters because the bike sat to long, so they are in a way weaker than carbs for race mixtures. Any lights coming on? my friend has a 02 gix 750 and runs full jet fuel been running it for a year and half no probs. To bad you do not live her I could get 1 of my friends to put it on the machine and tell you what your mixes are looking like.

 

Ya its FI, I may put some low octane in it maybe just to balance it out. When I do rev it there is some smoke that comes out of the exhaust. Im moving to Dallas in about 1 year, transfering to UDT.

 

Im having the same problem with my bike i opened my air box and cut my exhaust now when i let off it throws a flame.and it dosent like to idle when its warm

 

You completely changed the intake and back-pressure required by the engine.......so of course its' going to run like crap until you get the carbs rejetted. Definately running rich, which is ok for a cold engine, but once it's warm, you get what you got.

 

well close erik....but FI not carbies....so yeah ...YOUR FUEL MIXTURE IS RETARDED....

 

It is not uncoman to throw flames at high revs, You prob should take it in have them put it on the computer and see what your charts looking like. Both you you have new bikes and if you have been getting your regular service they should not act like that. Maybe it is a default and can be fixed free any reacalls on those bikes?

 

Alright the bike is 100% back to normal... Ram air all the stuff is on, and it still sounds poppy and choked and when it is reved to 6k it blows some black smoke... I have no clue what to do no it has about 600miles on it