XS-11 Dormant for Several Years

[HankD]

Group,
I recently purchased a '80 XS-11 that was sitting for several years and did not appear to be stored properly. The bottom half of the carbs were a solid chunk of crud, floats, float valves and needles were not salvageable. I replaced these parts with decent ones from a doner set of carbs and replaced the pilot and main jets.

The compression reads, 125, 110, 110, 120, from cylinder 1 thru 4. I have read several notes that suggest riding the bike for a bit and the compression may increase. I don't have this luxury now because the bike is not on the road (licensed) and winter is just beginning here in Canada.

My questions are:
1) When a bike has been sitting, what is the primary cause of low compression - rings or valves?
2) Is there a recommended product I can add to the cylinders (sparkplug holes) that can free up the rings or valves? What about penetrating oil?
3) Has anyone tried adding seafoam directly into the cylinders for cleaning carbon and freeing rings? I have only used it in dilated form as a carb cleaner but I know it is potent stuff.
4) If the head gasket has a leak, how can I diagnose this?

P.S. the bike runs reasonably well considering ..... but when I took it for a quick run around the block, it did not have the power that I was expecting. It was not as quick as my XJ650 so I know it is not up to par.

Thanks in advance
Hank

[Douglas Money]

Hank, if you aren't going to ride the bike at the moment, then the compression is a mute point. When you start to ride the bike, then worry about it. Until then, just work on the other stuff. Good Luck.

[prometheus578]

Usually the rings. the oil on the rings can gum up over the years from sitting and they don't feel like moving and sealing any more. Most of the bikes I get in the shop are non-runners and they smoke like hell when first started up, due to rings. I take a compression check first(which is usually low) but I ignore the readings till it has run for a bit. Your reading are all pretty level, so I wouldn't worry. If you had one or two really low, might be cause fer concern, might not be.
leaking head gasket: two adjacent cylinders with abnormally low compression(One blowing into the other) which you don't have. External oil leak, which you didn't mention. Compression blowing into oil port or cam chain cavity... a lot of blow-by into the crank area.. and smoke out of the breather tube going to the airbox, again, which you didn't mention.
don't be fooled by a lot of crank case blow-by at first running, as... with your compression being low, the pressure is forced past the rings into the crank... but that should clear over time.
sea foam would be good in the cylinders to loosen up things.
Pull the plugs and dump some in there. It'll eventually work it's way down the rings. crank it a few if you feel about it.
How much to add... who cares.
In spring, or whenever you feel like messin' with it again, pull the plugs and try to get the XS seafoam out of there before cranking. Crank it with the plugs out to "spray" the stuff out of they cylinders. (and it will spray!)
Get most of it out, as when it starts up, it will coat your exhaust pipes and then you'll have a real smoker on your hands till that stuff burns off.