Sign in to follow this  
Followers 0
charliemi16

WR400 Compression issues

3 posts in this topic

Hello everyone,

I have asked similar questions before, but am now trying to get the bike running again.

I've got a 2000MY WR400. Over time it got harder to start, particularly when hot. So, I checked and adjusted the valve clearances. It had been put away after washing and lacked compression, so at the advice of people on here, I put a little oil down the bore, and it started straight up. Since then it's refused to start, and I think it's a low compression issue.

I don't have access to a leak down tester, but have compression tested it, and get around 70psi. With a little oil down the bore, I get around 90psi.

Can someone tell me what values I should be expecting, as I can't find anything in the manual?

I'm thinking maybe it's time for a piston, as some on here have already suggested. What are people's thoughts? I'd like to be sure it's that before tearing it apart.

Thanks

Charlie

Share this post


Link to post
Share on other sites

I would think anything under 150 psi would require rings / rebuild. Normal range is 170 - 240 (I think...)

Only thing running on 70-90 psi is a lawn mower!

Share this post


Link to post
Share on other sites

You have no auto decompression system, so you are absolutely low on compression, BUT, YOU ARE TESTING A COLD MOTOR which means just about nothing

 

A 14 year old motor; if you have not rebuilt it, if you have no proof that the prior owner has rebuilt it, it's time to rebuild it. The top end anyway...

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

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0