Evaluating GS550 engine prior to purchase

[teh_engr]

Hello Everyone,

I looked at a 1981 GS550 earlier today and am now looking for more information about a possible engine problem.

According to the seller, the bike had not been started in ~1yr and had the old gas with a stabilizer. Also there was some rust in the fuel tank. Once started, the bike was only running on 3 cylinders. The fourth cylinder plug (the one furthest to the left when facing forward) was removed and showed signs of carbon fouling (possibly oil fouling but I don't think so). The seller replaced the plug with a new one (not properly gapped) and it seemed that the exhaust tube for this cylinder warmed up slightly afterwards but was not too hot to touch. Additionally, there was a small amount of white smoke in the exhaust associated with that cylinder.

I would like help in understanding what this particular issue is with this bike. After getting feedback and doing more research on price to repair other issues, I'll be taking a second look at the bike this evening and (hopefully) negotiating a sell. Advice on additional tests or possible problems and fixes for the engine issue would be very much appreciated. Aside from the engine problems, everything looks okay for the price (expected ~$450-500 after negotiations). Should I run away?

Thank you,
Jack

[Nessism]

Sounds like the bike needs a carb rebuild - simple job that is the right of passage with just about any 28 year old motorcycle. Rebuild instruction series is located on the GSR homepage. I also strongly suggest you update all the basic mainatinance before you put the bike on the road: intake boot o-rings, brake system clean out, valve adjustment, tank clean out, etc. All these jobs are fairly easy but require some work. If you do this work up front the bike will reward you with reliable service. Remember again, the bike is 28 years old and will need some TLC.

Hope this helps and good luck.

[tkent02]

Probably very minor, the carbs usually get plugged up from sitting, cleaning them out should have it running very well. If it has any kind of compression at all it is probably fine, even if the compression is low from sitting it will probably come up after running it a while. Not likely to be ignition as usually you would have problems on two cylinders, they share common coils. Could be a spark plug wire problem.

550 are very overbuilt and reliable.

If you don't want the bike, post the info here, someone will snap it up.
Like me.

[teh_engr]

Thank you for your opinions- I do hope your right. I've just now agreed to purchase the bike (my first bike) for $500 and am picking it up tomorrow.

I'll start a new thread in the future discussing what all needs to be done.

[Nessism]

If you go to repairmanualclub.com, you can download the factory repair manual for your bike.

Carb clean up series http://www.thegsresources.com/gs_carbrebuild.htm

Cycle o-rings:

http://cycleorings.com/#BS_Series_O-ring_Kit

http://cycleorings.com/intake.html

Good luck.