Will a leaky Petcock affect Engine Performance

Got one ordered but until then I have what I have. Stan

A guy showed up with an old 900 Ninja recently. the petcock was leaking so bad that it filled his crank case up with gas. How much gas? It was leaking out of the breather on the top of the crankcase.

I took the oil fill cap off and something resembling a milkshake came pouring out :ohmy: Two full drain pans later, it was all out. [pulled the drain plug at that point.

Bike was pushed aside because it's in such poor condiation. Two weeks later he wants to dump money into it against my advise. Another full drain pan of pure gas this time from the oil drain plug.

So if you have one leaking, you might want to check your oil level :S

What bike are you talking about ?

Is it leaking past the shut off or just around the out side of it and dripping on the engine?

On my 78 kz1000 and my son's 78 KZ650 they both leaked around the out side and just needed to be taken apart and cleaned.

If it leaks past the shut off you may have to replace a gasket, no big deal depending on your year and model.

Don't run it if you think that gas is getting into the crank case, look at the color of your oil and take the oil fill cap off and have a sniff.

JD

A bad petcock diaphragm can cause the bike to run like crap. Last year when my bike started running horribly, I discovered that fuel was spewing out the side of the diaphragm assembly while the engine was running.

A test you can try is to remove the vacuum line & cap the vacuum ports, then set the petcock to PRI to ride the bike. If the diaphragm o-ring is good & it seats properly, the diaphragm assy should now be bypassed.

With the vac line disabled, the petcock will now serve as a manual fuel valve: PRI will function as ON, while ON & RES should function as OFF. make sense? Note: do this as a temporary test, as there will be no fuel tank reserve when running the petcock this way.