Petrol smell

[erki52]

Morning all. Over the weekend I rode from Plymouth (UK) to Thruxton for our local round of British Superbikes. Distance was approx 140 miles each way. Bike ran absolutely great but when I stopped at the circuit and at the rest stop along the way I noticed there was a strong smell of petrol. The carbs weren't leaking but the starter motor cover plate looked damp. I'm thinking I might need to re-set the float heights and replace the float bowl gaskets.
Anything else anyone can think of? All advice / suggestions gratefully accepted.

Apologies, my bike is a 1978 GS750

[tom203]

I’d suspect the petcock…or its gasket mounted to tank.

[rphillips]

If float height problem, I'd think fuel should drain through overflow tubes & the bottom of the tubes are usually hidden. May be an idea, put bike on center stand, disconnect drain tubes from bowl nipples & run eng. for a few minutes, watching for a drip out of one of the nipples, or possibly a drip off a bowl, if a gasket problem.

[erki52]

Ta muchly for the responses. I will check the fuel tap gasket, the float bowl drains aren't visibly dripping but I will give them a clean off and check.

[allojohn]

Float height for me also.... fuel is likely soaking your bowl gaskets and it's slowly evaporating.

[Big Block]

Float height would likely muff up how it runs though.

[erki52]

Morning all. Might have found the issue, the drain screws are weeping fuel. More so on the left side which would make sense as this side is lower when it's on the side stand.

Found some o rings in work that fit just need to replace the rest and see if things improve.


Thanks again for all the help.

[salty_monk]

When that happened to me it was at the core caused by a leaky petcock... As it was a relatively new one I was able to clean some dirt out of the diaphragm and it cured it. If yours is old I'd replace it...