cam chain tensioner wr250f

[cw242]

i made the change to yz timing today but i had a question on the tensioner, when you engage it to tighten the chain slack do you let it wind up to its own tightness or do you turn it all the way tight with the screwdriver? it bottoms out probably a 1/4 turn past where it stops by itself, the chain is tight this way but does get somewhat tighter if you turn the adjustment all the way.... thanks cw

 

[wrooster]

cw242,
i did my timing change a few weeks ago. hold the tensioner in your hand. use a small screwdriver to "wind up" the tension spring. now get a third hand, your wife works well. holding the screwdriver to prevent the spring from unwinding, insert the assembly into the tensioner hole. obey the "up" wording on the tensioner housing so you don't put it on upside down. now finger tighten the two retaining bolts (this is where the third hand comes in, you are still holding the screwdriver tension). with the bolts finger tight, slowly relax the screwdriver pressure and let things come to equilibrium by letting the screwdriver slowly spin back a bit. pull the compression release, and using the kickstarter spin the engine over to ensure that nothing is bound up. if OK, then torque the two bolts to spec.

the wrooster

 

[Rich Rohrich]

Once you wind the tensioner in the clockwise direction far enough it will LOCK in place so it can be removed or reinstalled. A quick counter-clockwise turn will unlock it and restore the tension. It's spring loaded and designed to adjust the tension automatically. Based on what we've seen so far on the YZ400s it seems to do a pretty good job.