Minimum Cyl Compression?

[KevinF]

I'm a little nervous about asking this question but have come to the conclusion that it's time to look the beast in the eyes. I just ran the compression test... Results are #1 = 95psi, #2 = 120psi, #3 = 122psi, #4 = 118psi. Think I can slide by with the compression ratio on cyl #1? I was about to order rebuild kits for both carbs and the fuel pump.

 

[KevinF]

Re: Minimum Cyl Compression?

I forgot to mention that I have not had this engine running yet. It's been giving me a nitemare trying to get it started. If I prime the cyl's it will run for just a few seconds. From what I read in some of the other post's the compression is going to be an issue. Just wanted to get some feedback before I sink any more $$ into it.

 

[Laddies]

Re: Minimum Cyl Compression?

The engine should run on the compression it has, a dry engines compression don't mean much, all one has to do is lube it and you will get a increase so get it running and the see what you have--Bob

 

[Tatorbug]

Re: Minimum Cyl Compression?

No reason this engine shouldn't run with this compression. Get it running and warmed up and then check compression.

 

[Chinewalker]

Re: Minimum Cyl Compression?

If you find that the compression doesn't come back up and even, perhaps even after a decarb, then I would consider a partial rebuild. <br /><br />By that, I mean replacing that one piston and maybe re-ringing the others. As it sits now, it's possible that the piston is scuffed, but also possible that it hasn't yet taken the bore with it. Keep running it with a 25% difference in compression and that piston will deteriorate rapidly, maybe taking the cylinder bore with it. The longer it runs with the problem, the more likely the problem could become catastrophic, .ie tossed rod, broken piston, etc.<br /><br />- Scott