Jump to content
Sign in to follow this  

1999 rm 125 compression question

Recommended Posts

Hi,i have a 1999 rm 125 and it has 120 psi of compression,i just put fresh piston and rings in it.i have been told that that is bad compression for a 125 and that it should be 135-150 psi.just wondering what you biker dudes have any advice you can give me on what to do.should i resleave or re nickisil plate the cylender and what would be the cheapest,or should i go for a eric gorr 144 big bore kit? :thumbsup::confused:

DSCF3027.jpg

Share this post


Link to post
Share on other sites

120 seems low. I get 155 cold on my 2001. How does it run? Also, just to make sure, did you check the compression with an open throttle? If so, it could be a few things such as an air leak somewhere, or a worn out jug. Is the cylinder scored?

Share this post


Link to post
Share on other sites

it runs ok,have to have the idle screw almost all the way in for it to idle and ir seems to run a wee bit hot,what does doing the compresion test with an open throttle do?im prety sure there aint a airleak because it aint reving high or anything like that,just rebuilt the top end and tourqued everything to spec,the cylender wasnt scored at all,infact it looked pretty good to me.it had 120 compresion before and after the top end rebuild so i suspect that the cylender plating is warn out.it just dont seem to have all the snap that a 125 should have.

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:

Sign in to follow this  

×