Jump to content

Compression testing with auto decompression?


Recommended Posts

My friends 09' YZ250F suddenly stopped running and I'm afraid he might have fried the rings from running lean during winter. It has good spark, gas and air. It won't even bump start while getting pulled.

So we pulled out a compression tester and did the test at WOT. We got 60psi every time.

Then I remembered about the auto decompression on the cam but don't know how much it affect compression reading. It seems like the engine would never start with a compression of 60. What should a normal reading be even with the auto decompression?

Thank you.

Link to comment
Share on other sites

dont you have to do a leakdown test on those?
I assume so. But I don't think 60 is enough compression to get the mixture to ignite so even with an auto decompression system we 'should' get more then 60.

At least that's what I'm trying to figure out with this thread.

Link to comment
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:

×
×
  • Create New...