1981 Gs1100e

[Dwayne]

What should the compression be? I am getting 100 on my gauge on each cylinder.

[fgh]

What should the compression be? I am getting 100 on my gauge on each cylinder.

Can't say what it should be! Was the motor at operating temperature when you checked it? If no warm it up and recheck it. Was the choke closed and the throttle fully open when you checked it? If no get it at operating temperature and crank with the choke off and the throttle fully opened.

100 psi is low. I would think 140 is probably the suggested floor.

[Dwayne]

Yes to all. Is this a major concern? Will it greatly affect performance?

[don_gibb6512]

Excellent would be between 150-170psi. Be sure you're checking with a warm engine and the throttle held wide open. Normal on a used motor would be in the 115-140 range. 100psi is on the low end of the acceptable threshold. If you drop under 100psi or more than 15 percent difference on adjacent cylinders, you should consider a rebuild or refresh of the engine. Rebuild is new rings and pistons, honed and/or bored cylinders. Refresh is if the cylinders and pistons are still within spec and you can just hone the cylinders and go with standard sized rings. Get the head and valves checked and freshed up at a machine shop unless you can do that yourself. Not many guys have the expertise or equipment for that. My .02 worth is that if you've got 100psi on each cylinder and you're checking with a warm engine and the throttle held wide open, you will notice a significant improvement if you refresh that motor. Good luck on your decision.

[chef1366]

Check valve clearance before tearing the engine apart.