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I have an '81 Suzuki GS850L with 16k on the clock. I had a total rebuild on the carbs last summer (let it sit for 15 years in the garage) and it has been running great until about two weeks ago. My gas mileage started dropping off and I could smell gas when I stopped. I pulled the plugs out and 1,3 and 4 cyla nder were a nice light tanm but #2 was wet and black with fuel. The shop that did the rebuilds suggested running carb cleaner for about 3 tanks of fuel. I also changed out all of the plugs but it still runs rough and stinks. Thanks Tony

Sounds like a float problem.

That cylinder is either running rich, or not firing at all. Spray some water on your down pipes and then start the engine, to see if the water evaporates off it at the same rate, as the others.

If it does, that cyclinder is running rich. I'd expect it to be a straight forwards open up and clean the carbs, then rebalance them.

Otherwise that cylinder isn't firing, so time to look at why. I'd start with cleaning the spark plug up, with a metal brush.

Ted - Could be a float problem. Why would one float go bad?

Nibblet - I just replaced all of the plugs. I am getting spark on #2 but it looks sort of weak to me. Bad plug wire?

WS6DRIVER wrote:Ted - Could be a float problem. Why would one float go bad?

If your bikes been sat a long time you can get rust (amongst other gunk)in the fuel tank, which will eventually make its way into the carbs. This could cause a float to get stuck in the open position constantly pouring fuel into the cylinder when all the other carbs are sending just enough fuel to let the bike idle. In turn this would increase fuel consumption and cause that cyclinder not to fire correctly

WS6DRIVER wrote:Nibblet - I just replaced all of the plugs. I am getting spark on #2 but it looks sort of weak to me. Bad plug wire?

Could be bad plug wire, bad coil, bad connections, or as simple as the spark gap on the plug itself is the wrong distance.
Start with the quick easy checks first.
Does the head of the plug look like its the same as one of the other plugs? or slightly bent out of shape?
Also is the connector on the plug clean?
Try swaping the plug with one from a different cylinder, does the fault follow the plug or stay in the same cylinder?

All of the plugs are fresh out of the box and have been gapped according to the Suzuki manual. I may try swaping the plug wire from a known good plug.

Tony

How can a float go bad?

First determine what kind of floats you have. Metal floats and some plastic may get small holes that can sometimes be fixed. Plastic(solid), foam, or cork floats are coated. On most older bikes this coating is not resistant to ethanol and must be replaced with Al resistant floats. With some plastic (solid) or foam, they can be dried and recoated. Cork must be replaced. The way to check the floats varry. If they have noticable liquid in them they are bad. Others may be checked via weight.

Enough said about floats themselves. First check condition of needle and seat, as well as float level. Your problem is more likely to be this.

Thanks for all of the suggestions. I just did the old 4 barrel trick and tapped the carb with a screwdriver, added some cleaner and took a blast up I-95. It seems to be running somewhat better. I'll keep you posted it the thing blows up or something.

If you tapped it with a screw driver and the problem cleared up, you had foreign matter in the carb. No surprise in a quarter century old bike.

Sat for 15 years? You likely got crap in your tank which moved into the carb.

Don't run carb cleaner.

WS6DRIVER wrote:Ted - Could be a float problem. Why would one float go bad?

Nibblet - I just replaced all of the plugs. I am getting spark on #2 but it looks sort of weak to me. Bad plug wire?

You did all that work and didn't change the wires?