1999 Yamaha XL760 Stalls at Full Throttle

[geoffism]

I have a 1999 Yamaha XL760 and it stalls when I go full throttle. I have
- replaced all fuel filters even the one in the carb
- I rebuilt the carb
- replaced all fuel lines.
- compression at 140 and 150 psi.
-bypassed vent
-fuel system is basically new except needle and seat and they looked good.

And there is no change. Please help.


Thanks
G

 

[cfauvel]

not familiar with PWC, but based on that description...I would suspect a timing issue. I imagine like most other engines...the more air you put into it, the more advance the motor has to be with a max advance somewhere around 3000-4000....

If the motor is not advancing then the motor would lug...maybe not stall....but....

I'll subscribe to see the outcome.

How is timing done on these machines? Is there a magnet on the flywheel to denote crank position, and to trigger the ignition? I imagine there is a stator to provide voltage (300-400v) range to some CDI components, right?

 

[QBhoy]

Is the new fuel filter running not only the right direction, but also the correct way up ? There is an arrow for fuel flow direction, but also the way up it should be. Fooled me once and had the same symptoms.
Previous to this, I also put a normal in line fuel filter on it and it did the same. Fitted a oem yamaha one and it worked. Think they need a certain way of flowing. If you look at the oem filter it has a very distinctive shape and function.
Good luck.

 

[QBhoy]

Also check the fuel tank pick up pipe and lines are clear. Would cause same symptoms.