Head/base gasket and ring question

[cheezeweezle]

I have a1980 GS850 that I have done a good bit of work to over the last two months. My current issue is low compression on #2 cylinder that I believe is valve related. The compression test was run WOT, cold and dry, then cold and wet, (about a tbsp of 30 weight oil in the cylinder), and both tests yielded the same 30 pounds of compression reading. The other cylinders had 110, 110, and 120 pounds of compression to them.

I obtained a good head with @18,000ish miles on it and intend to replace the stem seals and use this head while I rebuild the original. I also intend to replace the base gasket while I'm at it as my bike has 55,000 miles on it.

What I really want to know is: Is it possible to reuse the rings on my pistons when I put the cylinder back on after replacing the base gasket? Is it advisable given the cold compression readings, or do I really need to hone out another cylinder I have,(20,000ish miles), and re-ring the pistons?

[Larry D]

IMHO, it's a case of..."you might as well, as long as you're in there."

New rings, nice hone, stem seals, gaskets, etc....I'd do the works simply because you'll already have it apart.

[tkent02]

Did you try adjusting the valves correctly?

[rustybronco]

What I really want to know is: Is it possible to reuse the rings on my pistons when I put the cylinder back on after replacing the base gasket?

FWIW... I took my '850 apart with 33K miles on it and reused the rings.

Did you try adjusting the valves correctly?

<<< Do this first.

[hampshirehog]

FWIW... I took my '850 apart with 33K miles on it and reused the rings.

Wow - a bit dodgy. Only another 50k or so left in them......

[tkent02]

Wow - a bit dodgy. Only another 50k or so left in them......

Or maybe 150K.

[cheezeweezle]

Did you try adjusting the valves correctly?

This was my plan for this week to see if it helps. I have never done it before but I have read the tutorials several times and think I can do it with no issues. I think the compression loss is an intermittent issue. I can heart a noise from the left side sometimes that sounds like an air compressor running at low speed, kind of a wet, sucking noise. When I hear that the bike runs a little rough. When the noise stops it feels a lot smoother, like a cylinder picked up and started firing again. I heard it a couple of weeks ago anf then it stopped. Now it's doing it again and I have low compression.

[tkent02]

This was my plan for this week to see if it helps. I have never done it before but I have read the tutorials several times and think I can do it with no issues. I think the compression loss is an intermittent issue. I can heart a noise from the left side sometimes that sounds like an air compressor running at low speed, kind of a wet, sucking noise. When I hear that the bike runs a little rough. When the noise stops it feels a lot smoother, like a cylinder picked up and started firing again. I heard it a couple of weeks ago anf then it stopped. Now it's doing it again and I have low compression.

Adjust the valves. There can be no compression if the valves don't close.