GS1100 Running Rich

[Anonymous]

I have a 1980 GS1100L that I can't seem to stop from running rich. It runs great as long as the plugs are clean, but after a short distance all four plugs are fouled and it runs progressively worse. I checked the fuel cock by applying a vacuum to it with a large plastic syringe, and it seems to be in good shape. Ignition system (ignitor, coils, and plug wires) is all brand new. The air filter is also new, and I there are no obstructions to air flow. As I look into the airbox where the carburetor air intake is, the sides are coated with what looks like a thin film of fuel/oil mixture. Is this a normal output of the breather hose? Also notice evidence of fuel running our the back of the carburetors against the flow of air. I recently rebuilt the carburetors in hopes of fixing this problem, but looks like it may not have helped. Based on what I have read in this forum, I am thinking I need to go back and check the floats and float valves, and maybe replace the main and pilot jets with something a little smaller. Before I dig into this again, I thought I'd get a second (or third, or fourth?opinion). Any ideas? Any recommendations on what size jets to put in? Any recommendations on where to get parts? I have ordered parts from an on-line source, but I am not sure the quality is what I want and it takes a while before I receive them.

Thanks for the help.

[earlfor]

Re: GS1100 Running Rich

Well, a slight oily film from the breather tube on the airbox isnt out of the normal. should be fine.

Fuel running out the back of the carbs is definately not normal. :-)
I would check the float bowl heightss very carefully, and check to make sure the float needles do actually shut off fuel.

I would not consider changing any jet sizes until I had the leaking stopped. I suspect the problem is with the mixture settings and not the jet sizes as I assume the bike at one time did run correctly on the already installed jets. I cant imagine the previous owner riding a bike running that rich and changing plugs every two miles. :-) (my two cents worth)....it seems to me that the most frequent inclination to remedy a too lean or too rich mixture problem is to immediately change jet sizes. My opinion is that probably in 95% of the cases, it is not the jet size that is at fault, but incorrect setup and tuning. A different size of new parts are no substitute for proper adjustment.

(I'm not making any kind of judgement here...just offering an observation) :-)

Earl

[Anonymous]

Running Rich

Thanks for the advice. I will start with the floats and float needles, and check the mixture. Is the mixture adjustment relevant above idle? Most of my riding is on country roads at 45-65 mph, so it doesn't idle much. I bought this bike last summer and put a couple of hundred miles on it, changed the oil, plugs, and air filter, and then for some reason it started to misbehave. I can't figure out what I could have done to cause this, but it hasn't run right since then.

[Anonymous]

If you have noticed the problem since you changed oil, plugs and air filter, you might have done something to any one of them.

Check that your oil level is not too high. If you are splashing oil around too much it can get past the rings and foul up your plugs. It looks like rich running but is really oiling up.

Check that you put in the same grade plugs that the previous owner was running. They should normally be 8s but might have been changed to 7s if the motor was running too cool and fouling them. This plug grade change is normally because of jetting changes.

Check that your air filter is the same quality and not causing air flow resriction.

Kim

[Anonymous]

GS1100 running rich

I don't think it is the plugs, as I tried the 7s and then the 8s with no significant improvement. I have wondered about the new air filter. Probably would be a good idea to change it with another brand just to see if it changes anything. The oil level is a good idea. I will check that. Unfortunately, I will not be able to work on the bike for a couple of weeks. Thanks for the help.