Have a 87 lt500 and it seems that when I twist the throttle to wide open it acts as if the key has been turn off. Am really lost as to what can cause this , any help would be great.

Have changed all electrical ( stator ,cdi,coil plug ) Have replaced petcock thinking filter pluged no change, Have rebuilt carb ( got all parts straight from mikuni,) " if it could be removed it was replaced " Removed kill switch, no change. please help ?????

 

tried carb jetting and bike seems to run better with 410 jet and needle set in top clip notch, still not perfect but am worried about running bike to lean any suggestions out there ?

 

If a bigger jet helped, then raising the needle helped more, I'd say you need a bigger yet main jet.
More air needs more fuel.
Sounds like your on the right track.
FYI: I would check the intake boot for cracks. I may even check the reeds.

 

betting air leak .. intake ,crank seals ect ....

 

Ya, me too.

 

have changed intake boot and reeds with factory new parts,
checked crank for play when stator was out didnt find any play at all so am thinking that seals are probably ok, dont know how else to check.
started with a 420 jet with needle set in middle groove, went to 410 jet with needle same, moved needle one notch at a time and the best it ran was with the needle clip in the top notch (wouldnt this make the motor run leaner ? ) so went down to a 400 jet and tryed moving clip one step at a time still ran better with 410 and needle at top groove. also tryed a 370 jet and instead of acting like the key was turned off insteadit bugged out untill it stalled out have not tryed any of this under load all testing has been in the garage.



thanks for the replies they are all a great help keep em coming

 

I run a 410 jet in my zilla when at sea level and a 400 at home. My needle is in the middle position.

 

took the bike out yesterday to jaw bone and ran it pretty hard, pulled the plug and it seemed to be alittle closer to white rather than tan, so i raised the needle one clip and ran the **** out of it the rest of the day, doesnt seem to like to cruise at anything less than 3/4 throttle but still has top end bobble like its trying to cut out. better than it has been but still not on top of its game. this was run with a 410 main and 30 pilot stock ngk plug and a 50-1 mix. bike ran better with this mix than it did with a 40-1 mix using hr-1 oil. any other combos that you guys could think of to try ?
thinking maybe since its an 87 that maybe i might have a bad head gasket maybe leaking into the cylinder instead of the outside?:huh:
what about maybe a hotter plug maybe a 7 instead of an 8 ?:huh:


all good info so far thanks:)