Brief description of how a the power valve works, and a detailed description of its operation an proper installation. Specific to 1989 Honda CR125R. Hoping to help someone in need not make the same mistakes I did.
I just watched your video you explain it well, I'm rebuilding a 1987 CR125 and the linkage was missing for the power valve. Where can I find the linkage and the little half moon plate spring and screw? I've checked E-Bay but unable to locate them for an 87. Will other years work as well like an 88? Any info would be appreciated thanks. Phil
Oof thats a tough one. Your best bet would be finding a top end or whole motor on ebay or facebook. They do come up. As far as year compatibility i know the 89 and 90 are unicorns, but im not sure about the earlier models. You may get lucky. You could always try to make one! Good luck phil
Thank you for your reply. I'll find the parts I need sooner or later sometimes you need to be patient. I'll send some pics when I complete the build Thanks again😎@@calebmacgray4588
I am in need of your advice lol I installed the linkage like you said and pushing down with all the slack out the holes line up perfectly.but… looking in the cylinder with a camera the exhaust valve is shutting the subchamber off when reved it’s opening the subchamber so it’s reverse from what that picture shows the bike is running like a dog
Are you working on a bike with the same setup as this 89? If so maybe you have the linkage assembled incorrectly? Id double check the pictures. 2:22 shows how the system should operate. Or it might be possible the valve is in the wrong position, if the flat face 8:13 is screwed up
So the case cover definitely has to come off? I just took the power valve actuator cover off, and unscrewed the arm linkage and small parts from the actual power valve, slid the power valve out and found that the opposite back end of the power valve which has the Phillips screw was completely broken off so the power valve could rotate 360 degrees. I ordered a new one of those and a new cover. Do you expect the timing to be off when I receive and install the new one ?
If the timing was initially set properly it wont change unless the case cover is removed. Make sure to line up the flat surfaces and align the half moons.
Replacing what exactly? Before i replace anything id be sure its properly tuned. But if parts looke like they are worn its never a bad idea to replace them. A properly functioning power valve will give you more low end and a broader powerband
i’ve got a 1989 cr125, it’s got motor and carb work done to it but still has no bottom end. never touched the power valve or sprokets. how can I give it some bottom end??
Honestly I'd just start by ensuring all these components are working correctly, the linkages probably have slop and the seals and bearings could be replaced. After that you could mess with the ignition timing by rotating the stator, especially if you do a lot of trail riding. The 89 125 was notorious for it high end performance, no so much low
If the carb/reeds/plug are okay, you can check if the power valve is moving correctly. Details in the video. The linkage cover behind the pipe can be removed to observe its movements
