Bad Compression #s and misc 80 GS550E

[Guest]

OK... background. Put about 60 miles on Wed with no problems, same thing a few days before. Took her out Thurs and began stalling coasting into any stop, clutch fully disengaged. This happened the first time I had her out and we adjusted the idle screw and hadn't had the problem since.

Anyway, I didn't do anything but add oil and took her out for a spin and it didn't happen. I was thinking I had lost enough oil (from a leak in the head, oil showing up in the right muffler pipe end and wet oily plug#1 more on that later) to make the bike overheat?? So maybe with more oil (not much more and I had to drain some out because I overdid it) and it didn't overheat today. Rode about 35 miles with no problems. Could that be it or some other gremlin?

Ok so the compression... checked that when I got home as I'm concerned about oil blowing past the rings. I'm getting oil in the end of the left muffler and plug #1 is black and oily. Here are my numbers, plugs have about 200 miles or so on them and are gapped to spec:

#1 90-100 (plug black and oily)
#2 - 140 (plug black and sooty)
#3 - 140 (not as black and sooty but not quite perfect tan either)
#4 - 115 (whitish lean - maybe just air mixture on carb?)

Could the compression/oil blow by be something simpler than rings? Someone suggested valve clearance. Wishful thinking?

So... how bad is it to keep riding with those compression numbers? What are the odds I can make it through the rest of my season here? [-o<

I haven't checked spark yet (my buddy took me 4 wheeling) Are any of these issues related? Besides checking rings and valve stuff, what else should I look at? What could some of my other symptoms mean if they are not related to the compression issue?

Thanks all... basically I am looking for quick fixes until I have to put the bike away for the Winter and a basic idea of what I will need to do then.

[Nessism]

Standard follow up step to low compression numbers is to put about 1 tbs of oil in the cylinder and double check the compression. If they go up, you have ring problems. If not, check the valve clearances.

As far as whether or not you can get through the season, hard to say. The condition of the engine is not likely to improve if the rings are to blame. To fix you are going to have to rebuild the top end with new rings (at least). It's recommended to measure the bores to see if they are still in spec. If they are, rings are enough. Otherwise you need either new cylinders or to have the engine bored oversize.

Sorry for any bad news this presents.

[MissFabulous]

Standard follow up step to low compression numbers is to put about 1 tbs of oil in the cylinder and double check the compression. If they go up, you have ring problems. If not, check the valve clearances.

Will do this next! UM suggested MMO in each cylinder. Will do this tomorrow or Monday.

As far as whether or not you can get through the season, hard to say. The condition of the engine is not likely to improve if the rings are to blame. To fix you are going to have to rebuild the top end with new rings (at least). It's recommended to measure the bores to see if they are still in spec. If they are, rings are enough. Otherwise you need either new cylinders or to have the engine bored oversize.

Or stuff a 750 into it... or something. Good cheap engines
can be had from time to time. If that is worse case scenario, it's not the end of the world, a long as I can wait until season is over to do it. :-D I can see from what you're saying tho that if it is rings I could be doing more damage each time I ride.

Sorry for any bad news this presents.

Not at all! Pretty much what I am expecting. I want best case and worst case scenarios! but I do want to ride... I can totally understand having several bikes roadworthy and titled at once. Thanks - exactly the kind of info I am looking for! Any idea on my stalling gremlin? Backfiring?

[chef1366]

Did you overfill the oil?
Take off all the spark plug boots and make sure they have alot of wire to grab onto.

If you overfilled the oil and had the bike on the side kickstand you might of filled the #1 cylinder with oil.

[MissFabulous]

Did you overfill the oil?
Take off all the spark plug boots and make sure they have alot of wire to grab onto.

If you overfilled the oil and had the bike on the side kickstand you might of filled the #1 cylinder with oil.

Well, yes, but it was black and oily before I did that which was just yesterday. I actually changed all the pugs because they looked so black (and the one oily) after I got it, so it's not a new problem. This was actually the only time I've ever let it really run for any length of time on the side stand since the first week or so I had it. The #1 plug is consistently black and oily. This is also the cylinder with the slow leak in the head. Crud got in though the hole and screwed it up??

[Nessism]

Well, yes, but it was black and oily before I did that which was just yesterday. I actually changed all the pugs because they looked so black (and the one oily) after I got it, so it's not a new problem. This was actually the only time I've ever let it really run for any length of time on the side stand since the first week or so I had it. The #1 plug is consistently black and oily. This is also the cylinder with the slow leak in the head. Crud got in though the hole and screwed it up??

I don't understand that statement. What kind of "slow leak" in the head?

Honestly, too much oil is not going to give you low compression numbers. Sounds like you have a bad cylinder; rings are either bad and/or the cylinder is worn. It won't hurt anything to ride it as is. Just bring spare plugs with you in case one fouls.

[MissFabulous]

I don't understand that statement. What kind of "slow leak" in the head?

Here is the thread plus pics: http://www.thegsresources.com/_forum...highlight=weld

End result is that I cleaned it from the outside and used JB Weld again and it's not leaking as bad as it was, but it is still leaking.

Thanks again!

[red bandit]

Hey Fab, the afore mentioned oil leak was not into the head but rather in the top of the head in the cam resivoir. The front part of the upper head above the the valve port was damaged when a shim came loose and was pushed out through the sidewall. It did not leak into the cylinder(I can't spell for S#*&), I never had a problem with oil in the #1 plug. This is not to say that it could be bad rings but I don't think the upper leak is the problem.As for the idle problems, if it seems to idle high the fall off it could be a vacuume leak. I had the vacuume line from the carbs to the pet cock(aka fuel valve) blocked because the pingel valve has not vacuume port. i had some similar problems as you describe when that plug in the line develpoed a leak. It may be a leak in some other line or a carb boot, but they are new and should be good. anyway remember that there is a part bike available in Buffalo.

[Jimmyd]

Compression Issues

Hey guys
I never say a new post on this issue.
I have a guy telling me a he has a GS 1150 with compression numbers in three cylineers between 140 abd 160 with the fourth cylinder reading 60
Yes I was told 60.
Is there any way that bike can be running even decent. With a difference in compression that big I have to guess this bike is about to overheat, blow at some point.
Any ideas on where to start?

[tkent02]

Could run OK, might idle roughly. They can run with near zero compression if the rpm is kept high enough.
60 is usually about what they read if you forget to open the throttle during the compression test. Could that be the trouble?
Could also be valves too tight, or something expensive.

[Jimmyd]

Compression Issue

Could run OK, might idle roughly. They can run with near zero compression if the rpm is kept high enough.
60 is usually about what they read if you forget to open the throttle during the compression test. Could that be the trouble?
Could also be valves too tight, or something expensive.

OK
Can you explain the compression process to me. I have never done a compression test on a bike.
How is it done?

Just seems logical that 140 to 160 in three cylinders and 60 in the remaining cylinder indicates a MAJOR issue in progress or about to happen.
I'm having a difficult time seeing that it may be just a valve adjustment.

[Jimmyd]

Compression Issue

Could run OK, might idle roughly. They can run with near zero compression if the rpm is kept high enough.
60 is usually about what they read if you forget to open the throttle during the compression test. Could that be the trouble?
Could also be valves too tight, or something expensive.

Also I have to guess that even if done wrong (don't know never did compression test) the compressions numbers would all be similarly wrong.

[SqDancerLynn1]

With just one bad cylinder ? Don't ride it without checking the valve clearances.

[Big T]

OK... background. Put about 60 miles on Wed with no problems, same thing a few days before. Took her out Thurs and began stalling coasting into any stop, clutch fully disengaged. This happened the first time I had her out and we adjusted the idle screw and hadn't had the problem since.

Anyway, I didn't do anything but add oil and took her out for a spin and it didn't happen. I was thinking I had lost enough oil (from a leak in the head, oil showing up in the right muffler pipe end and wet oily plug#1 more on that later) to make the bike overheat?? So maybe with more oil (not much more and I had to drain some out because I overdid it) and it didn't overheat today. Rode about 35 miles with no problems. Could that be it or some other gremlin?

Ok so the compression... checked that when I got home as I'm concerned about oil blowing past the rings. I'm getting oil in the end of the left muffler and plug #1 is black and oily. Here are my numbers, plugs have about 200 miles or so on them and are gapped to spec:

#1 90-100 (plug black and oily)
#2 - 140 (plug black and sooty)
#3 - 140 (not as black and sooty but not quite perfect tan either)
#4 - 115 (whitish lean - maybe just air mixture on carb?)

Could the compression/oil blow by be something simpler than rings? Someone suggested valve clearance. Wishful thinking?

So... how bad is it to keep riding with those compression numbers? What are the odds I can make it through the rest of my season here? [-o<

I haven't checked spark yet (my buddy took me 4 wheeling) Are any of these issues related? Besides checking rings and valve stuff, what else should I look at? What could some of my other symptoms mean if they are not related to the compression issue?

Thanks all... basically I am looking for quick fixes until I have to put the bike away for the Winter and a basic idea of what I will need to do then.

Okay, nowhere do I see a mention that you already adjusted the valves??

[MissFabulous]

Okay, nowhere do I see a mention that you already adjusted the valves??

*ahem* this post was like almost 2 years ago And yeah, that had been done.

It's from the hole in the head. I've JB welded the hole, which so far, has only managed to make the hole smaller (long story) and not completely close it. The bike runs fine despite the hole, just leaks some oil slowly. If you don't have a hole, it could be a piston ring, which is not a good situation.

To do a compression test, grab a compression checker from Harbor Freight (less than $20, or get a better one elsewhere) and follow the directions. A hose screws into the cylinder head where the spark plug goes. Fire up the bike, read the gauge - this is your compression. There are some home brew ways of doing this too, but I don't remember any of them off the top of my head. I think it could also be a leak at the gasket under the head. Maybe not as likely, but still a possibility I guess. IOW, in general, compression loss = leak. Scrutinize the crap out of the whole area to see if anything looks amiss, and as others have said, check those valve clearances.