cr 125 questions

Use whatever tranny oil you used in the blaster, but change it more frequently. 40:1 premix with proper jetting would be fine. Compression won't tell how worn the piston is, you're better off to do the top end before it fails, then you know what you have.

Pretty much anything clean. People use anything from 89 cent a quart atf to 8 dollar a quart high end tranny oil.

This will explain the difference quite well...............
http://www.dirtrider.net/forums3/showthread.php?t=146867

bel-ray gear saver 80w - run it in all my bike's trannies - never had an issue.

well if you are a normal kid i'll tell you what i recommend(and my book does too)10W30 in your tranny(i ride a kx125)

I have a 2001 CR125R. I run Honda synthetic 80W/85W HP trans oil, and Honda synthetic HP2 premix @32:1 (which is what Honda recommends for this engine. If you want to experiment you may want to read up on jetting a 2 stroke. I would rather see you use a stock spark plug and jet for your locale using the above stock fluids. Of course I can say that Honda fluids are higher priced than some. You can substitute other brands while sticking to the same specifications. BTW, I've had my engine apart multiple times and it always looks new and most parts have little wear. The top end wears quickest and installing a new piston and rings is a good idea when you buy a used bike. This model has no low end really and I found that by swapping the stock carbon fiber reeds with dual stage fiberglass reeds I picked up some low end while losing some top end. Also I went up a tooth on the rear sprocket. The rest of the bike is a great little tiddler even though they got bad reviews.