GL1100 Compression?

485 Views 5 Replies 3 Participants Last post by DriverRider, Jun 15, 2013

coachk64

Discussion Starter · Jun 15, 2013

When I recently changed the head gaskets on my 83 Interstate I also (because of a dumb mistake of mine) had to replace the right side cylinder head.

Now the bike seems to run well with no leaks, but it starts and idles strangely. When you press the starter switch, the engine turns very fast and you never get the "kick" of the engine firing. But when you let go of the starter button after only a second or so the engine just starts running. Initially the bike won't idle at all without the choke engaged, and after it warms up it will maintain an idle pretty well, but it's very low - around 400-600 rpm's.

It runs smoothly while riding it, but it seems to have lost some power. It still has all the power I need, but I can just tell that it doesn't have the power it had before I changed the head gaskets and the cylinder head.

So far I've only changed the spark plugs with no improvement. Is it possible that this used cylinder head from Fleabay has some defective valves? If so, is that easily repairable? Will continuing to ride it like it is cause more damage?

Looking forward to your input.

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Heffo

· #2 · Jun 15, 2013

You should really do a compression test first. If compression is good, consider rechecking the timing belt marks are properly aligned.

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coachk64

Discussion Starter · #3 · Jun 15, 2013

Thanks for the reply Heffo. I changed the timing belts when I changed the head gaskets, then had the right side off and on a couple of times. I checked each time and am pretty confident that the belts are on properly.

I agree that a compression check is indicated and I intend to do one. From the way the bike acts I'm pretty sure that the check will indicate a compression problem.

If it does, could it be the valves in the new cylinder head causing it? How hard would that be to repair? Or should I be looking for another used cylinder head, hoping for a little better luck? Will it hurt to continue to ride it?

Thanks again for the response.

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DriverRider

· #4 · Jun 15, 2013

I would be checking for tight valves if adjustable and check vacuum advance hose if applicable for proper hook up and advance action.

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coachk64

Discussion Starter · #5 · Jun 15, 2013

Thanks for the suggestions again.

DriverRider, I can't find any vacuum leaks, but I don't really know what you mean by proper hook-up or advance action. I'm not really a mechanic myself, but I try to do all my own work.

I know that until I do a compression check I won't really know what the cause is, and I'll do that as soon as I get the proper tools. But here's the situation right now. I lost a significant portion of last year's riding season because of the head gasket issue and I really don't feel like undoing all of that work right now for this issue. I don't have the funds to just drop it off at a mechanic, who could probably have it diagnosed and fixed in just a few days.

Due to what I've done to it, I really think it's the valves in my new cylinder head causing the problem, but, since it is running OK, I would really rather wait until this season is over to start taking it apart again. The thing I would most like to know is if continuing to ride it might cause more damage, or if I need to go ahead and bite the bullet and start wrenching now.

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DriverRider

· #6 · Jun 15, 2013

If you did the heads the rack was out I assume. The vacuum advance hose might not have been connected up right, it should go to the back of the engine and should make an idle difference when hose pulled on and off.

Even taking your time checking valve clearances is no big deal especially on that one head it should be done if that was the only thing that was changed to affect the running quality.

Like the mechanic used to say pay me now or pay me later.

Check the clearances and do a compression test, no cost and very little time involved. Then with the results an accurate determination can be made. The back yard compression test is to stick a finger over the holes and compare to your known? good side on left.

If after clearance check you have a low compression issue due to leaking valves it is all relative to how badly you need the ride. Whether a valve is burnt a little or alot it still has to be replaced.

Not an 1100 expert BTW.

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