2003 rm125 powervalve adjustment?

i have a 2003 rm125 that i just got and first time i went riding i noticed the bike wasn't hitting power band at all! First i thought it was the clutch slipping so i called the guy i bought it from and he said he changed both clutch and basket but he did tell me that when he rebuild top and bottom he didn't really adjust the power valve right and told me to check that before anything else. I wanted to know if anyone can tell me where the adjustment bolt is located and what i need to do.

is this where i can adjust iT?????????


Edited by maks630

Wish I knew how to help adjust, but I can't figure it out from looking at microfiche. You could take the lright side cover for the power valve and see if it moves freely and if the guy actually rebuilt the top end. If he didn't, it would be all gummy in there. Maybe someone else can chime in on how it's adjusted. Some bikes have a cover on the left side that turns to tighten and loosen the spring for the power valve, but I'm not seeing that on yours.

The cover above the exhaust pipe , is really hard to get off , with the frame rails, going down right in front.........I put my cylinder on ....then tried to put on the cover....no bueno'...learned that lesson.

You can , do what the above guy said....and take off the right side p/v cover...disconnect the plastic clip. from the rod....and then try and move the p/v...and get some idea , of your problem......should move freely.

Some say you can adjust the p/v .....I don't have the manual.....so can't really say....but I don't have any issue with my 05 rm 125....except a leaky carb bowl.

Runs like a top.

good luck.


If it's the same as the 03 250, which I'm pretty sure it is, it's on the top left on the cylinder. it's a little hand screw about the size of a silver dollar that has a 8mm head bolt on either side. Loosen off the bolts, let spring return to position, then turn 180 degrees clockwise and tighten off 8mm bolts to hold.

is this where i can adjust it?????

Edited by maks630

The right side is to access the rod .....which goes from the p/v to the crank.

You take off the rod.....to pull the cylinder...

The left side is where the adjusment cover is.....not sure what to do here....as I don't mess with mine.

But it has 2 8mm nuts to take off and then the slotted ( dime size cover) is either the adjuster or the cover to take off to gain access to the adjuster.

Nice pipe.

Good luck.


here is the other side

Thanks for all your help

It'll be top left under those breather hoses. A little different than mine, not sure on procedure. You'll need to obtain a manual or hopefully someone who has the same bike can chime in.

Remove right side cover and see if the power valve is sticking. Try turning it by hand. You may have to adjust it from the front of the motor under the cover above the exhaust. But you may need to pull motor to do that. Unless you disconnect the carb and radiator hoses, spark plug, then bolts and brackets to frame but not swing arm and maybe you could tilt it back far enough to get at the cover. If not, then only swing arm to pull to get it out. Check movement on right side first. Maybe push rod is not connected or something that simple.

You need a new front sprocket !!!!

There is no adjustment on that bike for the exhaust power valve. All you can do is check it for proper operation.

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