Amsoil and temporary loss of compression

2 replies to this topic
  • mcoulter

Posted November 01, 2005 - 06:18 AM


First off this is not another "which oil is better thread" - HONEST!

I have a lightly used 2000 WR400 which I'm guessing has less then 200 miles on her. I've put 3/4 of those miles on the bike so I know that the oil and filter has been maintained properly for most of its life. So here's what happened and I can't understand what could have caused this...

It was my 3rd oil/filter change on the bike and I decided to put in Amsoil's full synthetic motor oil. With the crappy weather we've been having in the northeast I didn't ride it after the change for probably 3 weeks or so, but this past Sunday was nice so I took her out. While the bike was a bit harder to start due to the colder weather, I was able to light it up after 6-10 kicks and then let it warm for a minute while I got ready. Well I pull out and the bike stalls (again no big deal) HOWEVER when I went to kick it over I noticed that I didn't have to pull the compression release. In fact I could easily push the kick start through by hand...

While visions of dollar signs were flying through my head I started pulling the valve cover apart expecting the worst.

Well to make a long story short everything looked fine. Timing chain, compression release lever, valves - everything was perfect. I noticed as I was testing things and pushing it through with the kick starter the compression was slowly returning.

Do you folks have any idea what could have caused such a drastic <<but temporary>> loss of compression? Really the only change that I made was using Amsoil. I rode the rest of the day and the bike ran well, there was not any smoke and everything seems perfect. :banghead:

It's just weird - any thoughts on what might have caused this?

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

Posted November 01, 2005 - 06:28 AM


sometimes a very small piece of carbon can catch between the valve face and the seat. producing the symptoms you describe.

  • Frostbite

Posted November 01, 2005 - 06:39 AM


This happens once in a while to my 99 400. I run Polaris 0W40 synthetic. I've had the bike since new and it only started happening after I installed a 430 kit last year. I pop the sparkplug and pour a drop of oil in the cylinder and compression is back 100%.
It's happened to me after the bike has been sitting for a few days and while riding. Strange. :banghead:


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.