1981 GS650G Katana with Mikuni BS32SS flooding

[Anonymous]

HELP... carbs are flooding out of the small "air passage?" opposite the air jet on the right hand side of each carb air intake. Fuel pecock functioning correctly, no air filters fitted. I took off one of the float bowls and put the petcock to prime then gently lifted the float to see if it stopped the fuel, it did so I'm assuming the needle valves and o-rings ok, float height adjusted as far as possible to cut off fuel sooner (probably messed that up now). I'm not talking a small amount of fuel here either, not drips but a constant flow. Engine does run but cuts out as soon as flooded. I'm on a low income and am really reluctant to strip the carbs unless absolutely necessary.. any ideas as to what's causing this?

[Anonymous]

You definitely don't want to adjust float level to try to stop overflow. You should set the floats per spec (probably as they were), and don't do that again. :? I don't know how reliably you can simulate the action of the float/valve by hand. I doubt that really tells you anything. There are lots of questions to ask, before one can know what is causing this. Is the valve needle grooved or worn, where it meets the seat? Is there possibly sediment in the seat? How do you know the petcock is working properly? If it were, there couldn't be fuel leaking with the bike off (unless set to prime). The truth is, if the bike is leaking while off and set to "run" or "reserve," that means that one or both needle valves are not seating right, AND the petcock diaphragm valve is leaking. I have had the same problem, and it can be frustrating, but don't worry about the cost aspect. It will just involve lots of tinkering, not a lot of parts.

[Anonymous]

follow up

I'm pretty sure the petcock is ok; It only flows when I suck the tube. I'd forgot to mention that the carbs were only flooding when the engine is running or when the petcock is set to prime... I find it difficult to believe that all four needle valve o-rings or valve seats would go at the same time, but the bike had been laid up for about 6 months till I bought it a few weeks ago, so maybe. I have read loads of previous threads which mention flooding carbs and a lot of them say that it is normal only when the petcock is set to prime. I can't get my head round this, as on other bike's I've owned with "normal" fuel taps the float bowls stop any overflow. Are GS's susceptable to failures of the needle valve seats and o-rings.

[duaneage]

I had the same problem. Dirt under the needle seats. If you drain the gas from the bowls and flush carb cleaner spray down the fuel line for 30 seconds you might be able to clean them off. Keep the carb cleaner off the paint and the clear coated engine cases, put rags over things to catch gas and cleaner runoff.

Or else you can tear down the carbs and that is a fairly big job and you'll need kits for all the carbs.

[Anonymous]

follow up - carbs still flooding GS650G Kat

Still Flooding - I've now reset all the float heights correctly, and I removed and inspected all the float needle valves and seats. All seem to be ok and the o-rings look alright. Nothing has changed though and when I set the petcock to prime, the float bowls fill and then fuel pours from the small "air passage?" (opposite the air jet on the right hand side of each carb air intake).. All four carbs flood at the same time, and it's a LOT of fuel, more than I think would leak through the o-rings on the needle valve housing if they did need replacing. Also, unfortunately, my hair is too short to pull out!! Any ideas anyone??