WR400 Compression issues


2 replies to this topic
  • charliemi16

Posted November 18, 2013 - 02:54 PM

#1

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

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Thommo_400f

Posted November 20, 2013 - 08:43 PM

#2

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!



  • Krannie McKranface

Posted November 20, 2013 - 09:23 PM

#3

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...






 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.