Jump to content

At My Wits End - 2002 RM125 Stutter

Recommended Posts

So I'm working on my co-workers 2002 RM125 that he picked up last summer for $500 - down the molehill we go.

He asked me to fix it up on his dime, so I did all the normal stuff to the chassis, new tubes, replaced some spokes, new cables, repacked the silencer...blah blah etc.

Now the problem - The engine has a mean stutter when riding it when it tries to come on the powerband - wont clean out and almost sounds like a misfire. Will clean out an run well when warm on the stand.

Here's what I've done and checked: Nothing has worked. (FSM = factory service manual)

-Head re-cut back to stock specs by Williams Moto Werx
-New piston ring
-Piston has 2~hrs on it
-Cylinder measured in spec (End of spec it has a steel sleeve) on a CMM
-Cleaned PV
-New Boyesen Reeds
-Cleaned carb
-Jetted per FMF spec
-Reset float height per FSM
-New Plug
-Verified PV is functioning
-Re-set PV spring tension per FSM
-New Airfilter
-Brand new FMF Factory Fatty
-Verified Electrical components (Coil, stator, kill switch) with multimeter and FSM

I'm leaning towards a bad CDI box, or maybe slight chance of left side crank seal leak (All thats left to check lol).

Anyone have any insights, sanity check, or a 2001-2007 RM125 CDI box laying around I can borrow to check bikes performance? Or that they want to sell?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×