CR125R Power Valve Air Leak

When attempting to pressure test my 2002 CR125R, it won't build pressure as the air is escaping through the power valve shaft.


I don't understand what's going on, the microfiche shows no seal in that location. Only the shaft and bearing, how does a ball or roller bearing seal?


As you can see number 21 is not listed for my year, also the way the drawing is shows that on the opposite side of the shaft. I'm thinking I'll replace the shaft and bearing, maybe the flaps too?


Current condition of the flaps: UDiBUEvl.jpg?2


Apologies for portrait mode...


The flaps should be fine. Get the other parts.

Flaps are so clean now :)


Got all the other parts, but the new bearing/shaft combo is the same. They all even measure down to the same half thousandth. So last night I got to looking more, and found in '03 they changed it from the bearing to an oil seal. I know the cylinder/cases for '03 is different from 00-02, but the valve shaft is the same; it's safe to assume (and only $4) that the seal will work in an '02.


I'll be picking up the oil seal today. Being that it's an oil seal, and knowing the dimensions (thanks Honda), the availability for a 9x18x7 seal is pretty good. Acura even uses the same part number on a transmission seal on an ILX.


I'll update tonight!

Oil seal is .030" larger in diameter and .080" deeper, but it fits so well on the power valve shaft. I'm going to machine the bore to fit.

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