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How bad is it to leave the fuel petcock open for an extended period of time? I forgoten about it from time to time and it hasnt seemed to make much of a difference. I read somewhere it can affect the carbs, how likely is this happen and what might some symptoms be?

buddhacide wrote:How bad is it to leave the fuel petcock open for an extended period of time? I forgoten about it from time to time and it hasnt seemed to make much of a difference. I read somewhere it can affect the carbs, how likely is this happen and what might some symptoms be?

Depends on the bike and the fuel flow setup, but leaving it open can allow fuel to drain through the carbs, into the cylinders, and settle inside the crankcase, fouling the oil.

Check your oil level and see if it smells like fuel.

If your carbs are working properly, you can leave the petcock on all of the time. I haven't turned mine off in 11 yrs. No problem yet.

The problem that Jonnythan describes above only happens when you have gunk or deterioration in the float needle. Basically, since the float cannot shut off the fuel flow from the tank, it causes the carbs to overflow when parked.

If you do have this problem, you'll probably smell a strong odor of fuel, and see fuel pooled under the carb overflow hoses. If that's the case, then it's a smart idea to shut the petcock off when parked. It's also a smart idea to get the carbs fixed, as they are probably running too rich at lower power levels.

If your float needles and carbs are in good shape, it shouldn't matter if you leave the petcock on.

on older bikes it is generally considered a good idea to always close it off. On a CBX, for instance, if it leaks it will fill the last cylinder on the down side and cause the a "hole in one" when started- either holing the piston or bending the connecting rod as it tries to compress the gasoline fluid.

Thanks guys. Good input.