Fixing Compression problems in GS1100

[Anonymous]

One of my cylindars is around 90 in terms of compression...the other three are around 130-140. If I'm going to open up the engine and fix the "one"..I'd like to just go ahead and fix them all.

Question: What should be on my shopping list in order to complete this job (minus tools...I have them)?

Thanks!

Rudi
1980 GS1100E

[Anonymous]

Maybe you should just ride the bike for a few months and not worry about it. From what I've read you haven't gotten much riding time out of this bike yet.

Cheers, Steve

[first timer]

put 500 miles on it change the oil ride a little more, test compression. if it is still low, check for valve tolerances, one of your shims may be to thick and not letting the valve close all the way. i would try these things before pulling the motor apart.

ryan

[Billy Ricks]

I agree with the others. Your bike has sat up so long you may have a stuck ring. Ride it awhile and see if it gets better.

[dgeorge]

Rudi, try running the compression test on #3 again if still 90 put about a tablespoon full of oil in it and try compression test again. If compression goes up with the oil in it then it is the rings if it doesn't go up then it is the valves. If you think you might have a stuck ring put some marvel mystery oil in that one cylinder and let it set for about 24hrs this will sometimes free up a stuck ring. Hope this helps, I'm going through about the same thing only all four of mine are down to about 90lbs. So I'm trying to redo the whole top end before spring, if I can get some of my other projects out of the garage so I can get the bike in there.

[cbxchris]

It could easily just be a carboned up valve. Put the bad cylinder on TDC and remove the valve cover. Lightly tap the retainers and check your compression again. Thats all it takes sometimes if you have a valve carboned up. I`m assuming you have checked valve clearances.

[Anonymous]

I agree with the others. Your bike has sat up so long you may have a stuck ring. Ride it awhile and see if it gets better.

You guys may be right...I HOPE SO! It would save me a lot of trouble. Then again, changing the rings isn't too hard, is it?

Also, my bike has 89,000 miles on it...but the oil was change religiously...plus there was an oil cooler attached...which kept the temp down. What are the chances that I'll need to bore my cylindars?

[cbxchris]

With that many miles I would almost bet on a rebore. When you check them your bores will be like a egg. Honestly you will also need valve guides and probably a set of valves. 89K is a lot of miles on a air cooled engine. Local guy claimed to have gotten 400K on a harley...I had a bridge I was wanting to sell but never run into him yet.

[Anonymous]

With that many miles I would almost bet on a rebore. When you check them your bores will be like a egg. Honestly you will also need valve guides and probably a set of valves. 89K is a lot of miles on a air cooled engine. Local guy claimed to have gotten 400K on a harley...I had a bridge I was wanting to sell but never run into him yet.

I just took it to a mechanic..and he said my valves are perfect. I know 89,000 is a lot...but then again the GS engine rocks!

If it WERE needed to be rebored...is that an expensive job? Just trying to gauge what I'm potentially up against.

[Anonymous]

Well Rudi, you'll need a top end gasket kit, oil, filter and a set of pistons/rings. Then there is machine shop labour and mechanics labour not to mention whatever else you find. Like Chris said, maybe you'll feel compelled to do the valves.

Steve

[mcycle-nut]

Machine shops are expensive! Around here it's $40 CDN a hole. With taxes that's almost $200 CDN, which is about $150 US! Does the bike run badly, ie. lags in power and burns oil? If not, forget about it and ride it! 8)

[cbxchris]

I`m assuming he checked the clearances when you say the valves were perfect. If and when you disaassemble when you check the valves where the seat contacts the lip of the valve a very definite lip will be worn in the valve. If its not to bad the valves can be ground and reused.(you cannot do this on a honda but can a suzy) The seats would need be touched up also. If you`re not into performance I would recommend OEM type pistons. I personally would use J&E`s. J&E`s start at around 325 a set. If you go that far probably would be a good idea to replace most of the seals in the engine and take it down completely to inspect. Roller bearing engines are a dream to work on compared to plain bearing engines. New timing chain and guides would be recommended.