YZ450F Hybrid issues

[Sandsjbyz22]

I built this quad in 03-04 and it has been very well taken care of. Recently I have been having problems with the engine leaning out. I have been all through the carb, the valves are tight, the air intake boot and the airbox are all sealed. I'm starting to think that it may be in the electrical. When I first start it up and take off its fine then it gets worse.

Has anyone had any problems similar to this? This engine hasn't given me any trouble in 4 years til now. Thanks...

[georgedoggy]

i have the same set up as you, and have had alot of tuning experience with these things!

what do you mean when you say its leaning out? what is it doing exactly?

[Sandsjbyz22]

Well it seems as the more I ride it say 2 or 3 minutes into riding the bike starts to backfire quite abit and when I pull the plug its bright white. It seemed like the timing was off but I checked that along with the valves and everything is where its supposed to be at. It is the first the bike has ever done this. My jetting is spot on with where I have always run it for the summer time and even going way to big with the jetting still didnt do anything to help.

[ss440ex]

cdi maybe going bad????
Does your carb have the tps on the L/H side of the carb?
Ck those wires for any disconnects.

Good luck, keep us posted!

[georgedoggy]

forget looking at the plug, its not a 2 stroke.

if it starts backfiring on deceleration you either have an airleak (pipe fell off, header not tight, airboot leak etc etc) or its your jetting. On deceleration its your pilot jet or fuel mix screw.

the first thing id check is the header bolts and the airboot. then the jetting. it doesnt sound electrical too me..

over and out.....

[jrspawn]

Check the crush/seal ring in the head for the header.

Thank you
Justin

[ss440ex]

[QUOTE]Originally posted by jrspawn
[B]Check the crush/seal ring in the head for the header.

Or any cracks in the head pipe.

[Sandsjbyz22]

Thanks for the help...

georgedoggy; Dont worry I started off on a 250R still wish I had it, but to me a spark plug doesnt lie 2 or 4.

[racerx573]

Did you change the type of fuel you're running compared to the past?