021 Re-Ring?

[KennyW in CT]

Got an 021 that has low compression (85 psi) but runs great once started. I squirted some oil into the cylinder (old trick to test worn rings I was told) and after 4 or 5 pulls started up and ran and idled nice.

Cylinder isn't scored, just seems like the rings have lost tension; they are not stuck.

Can I get away with just removing the cylinder and putting in a new set of rings?

What about the base gasket?

Will I need to get nikaseal stones to hone the cylinder properly or just scuff the cylinder and install the rings?

Thanks,

Kenny

 

[Fish]

No base gasket, just sealant.

Are you sure the psi is accurate?

Just replace the rings if there is no scoring, if you want to.

 

[KennyW in CT]

My Makita DCS340 puts out 145 psi, and it's a well worn saw, also a 372 I had put out 140 psi, so I think my compression tester is probably ok. 85 seemed way low to me too, the rings on the 021 barely have any tension but are free in the ring grooves. Kenny

 

[Rookie1]

I ogree with Fish 85 sounds pretty low to have it start and run fine. Have you put it to some wood? Anyway If you want to rering it you should hone cylinder. I use a"dingleball hone" and dont overdo it. Also engine is a stand alone unit inside plastic cradle,take a look underneath and youll see 4 torx that hold it in. Like Fish says too it takes a gasket maker not a paper gasket.

 

[KennyW in CT]

The first symptoms were that it wasn't starting with tons of mix flooding out of the muffler. Even ether wouldn't light it. The spark is bright, I know it's getting fuel, so I hooked up the compression gage. I also kept it full throttle with open choke to get an accurate reading. An old timer who has taught me about small engines told me the trick about squirting oil in the cylinder to confirm worn rings, and 4 pulls after I did it she started up. That's why I'm thinking just rings. The chain needs replacing so I'll probably do that and try it in some wood. Kenny

 

[KennyW in CT]

Turns out the rings were stuck on the intake side. Freed them up and now she has good compression and starts on the 2nd pull. Thanks to all who helped out. Kenny