how low is too low for compression?
 

I am just curious as far as what compression figures (PSI) I should be leary of in doing a compression test. I have one engine I got 60psi out of (after many pulls) and it was scored to heck... one that was to 90 and looks new inside (but ring gap is in the exhaust port, can't help anything I'm sure) and one that was at 100 or 110 and ran like new. I've only ran the last one I mentioned, I tried to start a ryobi that I measured to 90psi, but it wouldn't run (could be fuel or spark)

I was just curious and figured I'd ask those that have more experience with various random engines...

RE: how low is too low for compression?
 

Homelite blower service book sayes 12 to 15 pulls on starter.
90 psi hot
100 psi cold

RE: how low is too low for compression?
 

somehow I missed your reply... just what I wanted to know!

I've been doing like 4 pulls on the starter. I've never bought a two stroke engine other than two glow engines new in my life, so I haven't seen much in the way of manuals for these :)

Thanks

RE: how low is too low for compression?
 

Anything below 75 psi is pretty well impossible to start.

RE: how low is too low for compression?
 

Over 100 good, Under 100 not so good, Under 80 the only way it will fly is if you throw it in the trash!

Rich

RE: how low is too low for compression?
 

My FeatherLite 18cc would eventually start by hand flipping, but would only turn a 16-6 Top Flight Super M 5700rpm. Compression was 35 to 40 lbs, ring gap .012". This was using gas glow. Does anyone have the service limits for the ring gap on these. Its possible the motor was run hot and removed the ring temper? Or maybe the ring bevel is gone or worn...glazed cylinder etc. We found the weedeater in the dumpster, but they also get pitched when the string won't feed right. The bore looks like chrome and I assume it is, is it advisable to polish with a fine hone?

RE: how low is too low for compression?
 

Specified ring gap in these size engines is usually 0 to .003". Your ring gap is four times wider than it should be. Contact Frank Bowman for the best rings made...

AV8TOR