QuestionI would like to know how to re-install the exhaust power valve linkage so that the marks line up.
AnswerMark,
you might need a manual or at least
a parts diagram for this.
http://www.cmsnl.com/img/exhaust-manifold-87-89-cr125r-89-us-partslist-big-HU026...
Here is some info I gathered that might help
if it applies to your situation:
On Hondas and Yamahas there usually is a small hole in the cylinder and a hole or goove in the linkage arm. Adjustment is done by putting a rod, of the right size, in both holes, locking the power valve closed. Now loosen the adjusting bolt on the linkage arm, then tighten it.
To check to see that the powervalve is adjusted correctly, remove the bolt on the left side of the engine (above the shifter). I think it is 17mm. There are 2 marks inside. One is for when the bike is idling. The other is for when the bike is revved. At idle, the groove in the shaft should line up with the"L". While revving the bike, the groove should move and line up with the "H". After removing the bolt on the cylinder, all of this will be very clear.
After you adjust the powervalve linkage take that 17mm bolt off the left side of the cylinder and rev the engine like block said...although just a little rev won't do it...you need to rev it up to around 1/2 throttle or so...I think the Powervalve starts to open at 6,000RPMs..so just grab a handful of throttle and then watch to see if the slot turns to the "H".
http://www.atvlegacy.com/pwrvalve.htm
http://www.dansmc.com/powervalve.htm
You should see the power valve arm move when the bike is reved (with the cover off on the side where the arm is).
If its stuck open, then low end suffers and top end is normal. If its stuck closed, then low end would be normal but top end suffers.
Have you verified its correctly adjusted (use the locating pin to hold it in correct position when the actuating arm is attached)? If you have the manual, it will show this. The bikes came (still do) with a pin which aligns and holds the powervalve assy when you attach or remove the actuating arm. Of course the pin comes out before running the bike.
