Compression Test Advice

[hotspur]

Hey Fellas,

Need some advice on compression etc.

Did a compression test today.
First run dry: #1cyl 110 #2cyl 90 #3cyl 90 4cyl 110
Second run wet #1cyl 120 #2cyl 140 #3cyl 140 #4cyl 140
It is a 1980 GS850G with 98600 kilometres on it. When I got the bike it hadn't run in 4 years and in the process of putting it back on the road.
It was my first bike, sold it 7 years ago and then found it again so it has sentimental value but I dont want to spend a house deposit on it. It will be an every now and then ride, couple thousand kilometres a year, as I have a BMW as my main tourer.

What do you fellas think? Leave it as it is and get it on the road fix it when it dies or do the rings etc now.

Any advice from you wise sages would be fantastic


Cheers

Kieren

[Greg O.]

Sounds like the rings are bad. Maybe just suck from sitting. You could try pouring some Marvell Mystery oil inside the cylinders and let them sit for awhild, and this will sometimes free up stuck rings. I have seen this work on a Chevy 350 marine engine, mine. It had one cylinder that was 40 pounds lower than the rest. I let it sit over winter with MMO in it and the compression came up in the spring.

Oh when you do a compression test, be sure to open the throttle all the way. If you didn't do the test again.
Greg O.

[jetta90]

Kinda hard to argue against the "oil in the cylinder" results, and at 98,000 kms the bores/rings will indeed have some wear...................
but be sure you have your valves properly adjusted.
If they are a little on the tight side it might just be enough to skew your compression results.
Have you checked your valve clearances?

[hotspur]

Haven't checked/adjusted the valves yet, but that will be my next adventure.

[mark]

Your "wet" number aren't bad. If it runs O.K and the basic maintenance is up to speed, I'd say ride it.