Three rides ago the throttle on my 2002 yz250 stuck open for a moment . I checked everything ie pulley , cable , spring retainer position , dirt etc . All perfect ! Last ride it happens again ,scary !
While loosening the carb top I hear a clicking sound from the slide being struck by the tps position roller. With slide out of carb I can and pulling tps up , I can easily recreate this condition of the tps stuck in the wfo condition . As i loosened the sender unit screw slightly the binding stopped , tightening it brougt binding back.
On stripping the tps unit I saw a very distinct bright wear mark on the shaft . I used 220 grit emery paper to sand down the shaft and on re-assembly all binding was gone.
the tps unit spring probably accounts for a third of the slide return force and if it is stuck it will send wfo info to the advance/ retard
progam,causing the mystery sticking throttle ( I think ) . Will be
trying it out this weekend !
While loosening the carb top I hear a clicking sound from the slide being struck by the tps position roller. With slide out of carb I can and pulling tps up , I can easily recreate this condition of the tps stuck in the wfo condition . As i loosened the sender unit screw slightly the binding stopped , tightening it brougt binding back.
On stripping the tps unit I saw a very distinct bright wear mark on the shaft . I used 220 grit emery paper to sand down the shaft and on re-assembly all binding was gone.
the tps unit spring probably accounts for a third of the slide return force and if it is stuck it will send wfo info to the advance/ retard
progam,causing the mystery sticking throttle ( I think ) . Will be
trying it out this weekend !