Engine Problem

[550Leric]

Hello,
I am new to motorcycles and just recently purchased a 1985 GS550L. Prior to me buying the bike, it had been sitting in a shed for about two years. Supposedly the bike had ran fine before being stored, and all it needed was a carb rebuild and tune-up. I got the bike home and tore into it, cleaning the carb, with new needles and seats and a petcock rebuild kit. The wiring was a mess, with duct tape used to help splice a few wires together and a few wires cut completely. We fixed most of the wiring and have been trying to get the bike to run. It will not even sputter or run, except on two occasions it ran for less than ten seconds. The first time only the second cylinder was firing, then the next day only the first and fourth would fire. The engine has compression, spark, and fuel is in the carbs. Any ideas why the bike will not run?
Thanks for any input,

Eric
85' GS550L

[Nessism]

When you say you cleaned the carbs what did you do exactly? It's always best to do a complete tear down since the various o-rings get dried out and leak. Also, the pilot circuit is deep inside the carbs and the jet has a very small orifice which most people miss the first time. Lastly, the carb boot o-rings are sure to be hard and leaking if you didn't replace them. All of this stuff is the right of passage for getting a "ran when parked" GS back on the road.

Good luck.

[550Leric]

Yes, my buddy and I completly tore down each carb and cleaned everything, with his dad, who has over 15 years experience rebuilding carbs, checking our work. We also replaced various o-rings, since several did seem dried, and not in the best condition.

[fgh]

It sounds like it must be the ignition. How do you know what cylinders are firing? I would take a timing light and test each cylinder while cranking. If it doesn't flash brightly and consistently on each cylinder then you've got a ignition problem.

[gustovh]

I would start with a new battery. The battery may have enough juice to turn over the motor but not enough to create the spark that you need. Had a 850 that would crank all day but not run, new battery and game over, started right up. For what it's worth.
V

[Steve]

I'm gonna send you back to the carbs.

How did you "completly tore down each carb and cleaned everything"? Did you dip the carb bodies overnight, or did you just spray and brush what you could see? To do a proper job of cleaning, you need to dip them overnight AND poke a strand of copper wire through all the passages that you can see and the holes in the jets, follow that with a spray of carb cleaner (wear your safety glasses :shock: ) then compressed air to make sure it's clear.

THEN you can put in the new o-rings and put it all back together. While you have the carbs out (again), order the new o-rings for the intake boots from Cycle O-rings.


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[nabrams]

OK, here comes my "speech to the newcomer restoring an old bike":

I think you need to see the big picture besides tackling your immediate/first problem. There are MANY possible causes for your problem.

Having said that:
Instead of going about the restoration process piece-meal, why don't you search for the many posts on this forum (some by me) that list the many "sanity-check" steps/verifications needed when restoring a bike that's been sitting (based on what you've said, you definitely should consider your bike as belonging to this category) - and then actually DO the checks.
This will save you MANY hours of frustration and TONS of money.
If you're a beginner (in terms of mechanical skill) you're looking at between 30 and 60 hours of work and a couple of hundred dollars for purchasing tools you'll need (besides whatever parts you need for the bike) - just trying to give you a realistic estimate based on personal experience. In the end you'll have a reliable machine for a fraction of the cost of a new bike.

[jimcor]

Buy some new plugs. You won't be the first to find out the old plugs won't fire under compression, but will arc out of the engine. So you're worse case, if I'm wrong, is you're out $8, but that's one less thing to check.