'01 CR250 Powervalve not opening - Governor Problem?

[Chupacabra]

I just completed a top end rebuild on my 2001 CR250, and the power valve isn't opening. To confirm, I removed the cover (17mm nut) on the left side and revved the motor to see if the power valve notch rotated from the "L" mark to "H". It stayed at the "L". While bolting the cylinder to the bottom end, I made sure that the linkage fork on the cylinder aligned with the pin/pinion on the bottom end. Before assembly, I also removed & cleaned the valves, and they were moving smoothly afterwards. Upon disassembly/assembly, is it possible that something may have happened to the governor/pinion that made it inoperable? Before the rebuild, everything worked fine.

 

[evenslower]

So you get no movement at all I'd guess the fork on the bottom of the cylinder isn't connected to the little actuator "thingy" on the bottom end quite correctly. I think the two arms (one on cyl and one on case) are at a 90 deg angle with each other when full closed.

Is the slot in the center valve completely clean. Its a pretty common issue and sometimes it takes a small round file to get it absolutely carbon-free. Boogered me up once. Other than those two maybe the actuator arm not in the right position when everything was buttoned up.

Hope that helps. Its been a while since I've had my hands on one of those. Had a manual once.........

 

[Chupacabra]

I believe the valve slot should be really clean, because I disassmbled everything and cleaned. Afterwards, the powervalve assembly moved freely/smoothly. As far as the fork (cylinder) and stub thingy (bottom end) alignment, yes, I believe their positioning is 90 degrees. I'm pretty sure I got the fork inside the pin. The only thing that I can think of is that maybe the pinion/stub on the bottom end wasn't in its correct position. If that was the case, how could I rotate? Lift it and turn to correct position? Damn, I hope I didn't break anything. Looks like I'll be taking it apart again...

 

[James]

If the pin is in the fork, check the clamp at the top of the shaft and make sure it is tight (can you turn the valve manually when the engine isn't running?). Did you have the upper linkage assembly apart? If so, there is a procedure for adjusting the valve assemby after you have it apart. Do you have a manual?

You won't be able to reposition the pinion in the lower case because it is spring loaded.

 

[Chupacabra]

Good point, I'll have to double check the clamp tightness and everything (fork, etc.). If the clamp is tight, then I shouldn't be able to rotate the valve, correct? The funny thing is that I have the owner's manual for reference and I've done this once before without any problems. I thought I was being careful with the procedure, but maybe I messed something up....

Thanks for the advice and pinion (bottom end) reposition info. At least I know that I won't have to mess with that.

 

[James]

That's what I am thinking. If the clamp on top of the shaft is loose, the engine won't be able to turn the powervalve but you should be able to by hand with little resistance.

One thing that helps me get the fork and pinion aligned when reinstalling the cylinder is to have that top clamp loose and the clip out so the shaft with the fork hangs lower than the bottom surface of the cylinder (it may fall out but I haven't done that yet) so I can set it on the stub/pinion in plain sight and then lower the cylinder down into position.

That thing is what makes the whole top end job a pain. It is pretty easy otherwise.

 

[kuritaro9]

also,it is possible to get the bottom shaft 45deg. opposite. i think the pin is supposed to be on the inboard side. i have done it before. and the bike will fall flat on its face.makes a really muffled sound instead of reving out.

 

[Chupacabra]

Kuritaro9, when the bottom shaft was in the wrong position (45deg. opposite), how did you get it in the correct position? It didn't seem to want to move.

James, thanks for the fork alignment procedure. That should make assembly a lot easier next time.