1981 gs850gl low compression

[syren]

Did you hold the throttle open?
60 is about what they read with the throttles closed.

No, I didn't. I didn't know I had to. Doh! I dont hold the throttle open when I am trying to start it though do i?

[Steve]

Doh! I dont hold the throttle open when I am trying to start it though do i?

No, you shouldn't hold the throttle when starting the bike.

BUT ... you are not trying to start the bike, you are trying to get compression numbers.
The correct procedure for getting compression numbers is to hold the throttle wide open. Ideally, the engine should be at operating temperature and all spark plugs removed.

The difference between "wet" and "dry" readings refers to doing the test "dry" first. Just hook up the gauge and get some numbers. If they are low, add a teaspoon or so of oil to the cylinder, then try it again "wet". If the rings are bad, the oil will help seal the rings and the compression numbers will rise. If they don't rise much, your problem is likely with the valves.

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[reddirtrider]

Changing the head gasket can turn into one of those "snowball" projects.

Bumping things enough to get the head loose will usally disturb the base gasket, so you had better figure on replacing the base gasket, too.

Of course, you have to remove the cylinders to change the base gasket. Since the cylinders are off, check the rings. How many miles on the engine? You might want to change the rings, too.

If you replace the rings, you will want to hone the cylinders.

Whether you do the base gasket or not, the head is definitely off. Since the head is off and you likely got new seals with your gasket kit, you may as well replace the valve seals.

Don't forget to check the cam chain for proper length before you button everything back up, too.

Time:
To remove the head, maybe 15-20 minutes. Another 10-15 minutes will have the cylinders off, too. Depending on how the previous gaskets were installed, you may have clean mating surfaces or you may have to do some scraping. Figure about an hour for putting things back together, then a bit more for re-checking things, including valve adjustment. Overall, 4-6 hours, depending on how much gasket scraping you have to do. Best part is that it can all be done with the engine in the bike.

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You forgot about splitting the cases to install the new cam chain. Then replacing crank seals, ......, and on and on..... Good list though!