Time for a rebuild?

[Guest]

Seems over the last 1000 miles my 1982 GS1100GL bike had been losing some power and finally took the time to figure it out: cylinder #3 has only 75 PSI on a compression test while the other three cylinders are in the 110 PSI range.

I check the valve clearance for #3 and it is within spec.

On the head I've never taken anything off below the valve cover gasket so this is all new territory and I'll be seeking out suggestions and tutorials.

Just before I begin, is there anything else to try?

Please let me know.

Thanks so much.
-Bob

[SqDancerLynn1]

Go back and check compression again with the throttle wide open...
If it still only reads 75psi It's time for a re ring

[littleroot]

Go back and check compression again with the throttle wide open...

Somehow you knew I had not done it right, eh?

Thanks, I will do that!

[blowerbike]

sinc those radial slides and power will come back

[littleroot]

Here is the compression test results with the throttle open

1-155
2-150
3-150
4-160

Not horrible. I know I have some valve adjustment to do

2E less than .0015
2I .004
4E .004

So just sync the carbs?

Unfortunately I have three broken valve cover bolts, snapped at the head, two were from PO and one I did this week . I had a little leak from the cover-to-head seal just above the #4 exhaust and it either goes right on the pipe or streams down on my leg/boot. So I was half hoping to pull the head. Maybe I will have another go at getting the bolts out or hire someone to do this if for sure I do not have to pull the head.

By the way, the bike has 36k miles now.

Thanks for any and all advice.
-Bob

[SqDancerLynn1]

The only thing I can say is take your time !!! Don't rush the job. Do you have the cam cover off ? Could gain more access> Is it a bolt that goes into the cam hold down/ bearing ?? If you try drilling them ? USE a left hand drill bit !!!!! What I have done Is to drill a hole in a small block of aluminum that is squared on two end surfaces as a guide

[blowerbike]

radial slides on a daily riden bike can go out of sinc a couple times a year.
this will make the bike not run 100% while crusing and run some what rough until the throttle is wide open.

[GSScoobie]

Here is the compression test results with the throttle open

1-155
2-150
3-150
4-160

-Bob

Wow! That is a nice tight engine after all of those miles.

[littleroot]

The only thing I can say is take your time !!! Don't rush the job. Do you have the cam cover off ? Could gain more access> Is it a bolt that goes into the cam hold down/ bearing ?? If you try drilling them ? USE a left hand drill bit !!!!! What I have done Is to drill a hole in a small block of aluminum that is squared on two end surfaces as a guide

Let handed drill bits - never used those. One of the bolts is under the frame but the other two are accessible. Thanks for the tip on the guide

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