87 RM250 exhaust valve question

cliffy13 · Feb 4, 2005

Hi all. I just discovered this site and it looks like there are some very knowledgeable people here.
I have an 87 250 RM and wonder about the proper operation of the power valve governor. I've looked at this thing six ways from Sunday and can't seem to figure out how its supposed to work!
The driven gear on the governor (Suzuki's term, from the crankshaft) has what appears to be a clutch on the back side of it which rides on a thrust bearing on the valve actuator. (does that make sense? lol)
Question: Is the clutch thingy activated centrifugally, i.e. with increasing RPM?
That's the only way it makes sense to me but I can't seem to get it to engage.

Thanks for any and all opinions/assistance.

OldTimer · Feb 5, 2005

I'm in the same boat with my Huskie, I came here to post a similar question.
I know it's a different bike, but the manual says that, what Huskie calls H.T.S. exhaust valve, is centrifugal and opens at 6000 rpms. I'll bet yours works similarly(sp). Maybe you have some idea what the darn thing's for?

CRguyStan · Feb 6, 2005

The power valve actuation for these does come from the RPM of the crank. When high enough this gear actuates an arm that opens the power valve (normally partially blocking the exhaust port) and effectively raises the exhaust port while also increasing the opening. This creates the "power band" and provides the top end hit.
Cliffy, when you say you can't get yours to work, do you mean by spinning it by hand, you'll never spin it fast enough. If the valve does not work, this is normally caused by either gummed up valve and/or actuators from premix oil, or by broken levers that connect the drive mechanism to the power valve assy.
Stan

cliffy13 · Feb 6, 2005

Thanks for the reply. I finally bit the bullet and disassembled the governor mechanism last night: NOW I see how it works! lol
I'll just have to reassemble the top end after the bore job and peek through the little window to make sure it's working properly.
Manual? We don't need no stinking manual! lol

87 RM250 exhaust valve question

cliffy13

OldTimer

CRguyStan

cliffy13

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