Pet Valve Question *****************

Is there a slim chance that a faulty Pet Valve could cause gas in the oil.
I was reading another forum I wont mention BUT, a member said this was so.

 

If your auto pet cock is not shutting down & your carbs are the type without overflows, yes, gas can find it's way into the crankcase.

 

There would need to be either a bad o-ring or weak spring to allow fuel to leak by the petcock. I'm not 100%, but in order for fuel to make it all the way to the crankcase the float needles also need to be worn, otherwise the fuel would rightfully sit in the float bowl with no way to get into the engine.

 

If that does happen, you will need to go through your carbs as well. Your carbs are not supposed to overflow gas into the airbox and down into your crankcase.

 

+1

The vacuum fuel valve is a safety in case the float valves aren't closing tightly. You need to correct both problems.

 

Yep.

If your floats are working properly, you could leave the petcock on PRI for days and nothing bad would happen.

A petcock that won't shut off properly is effectively providing the same result as being in PRI, so if you have gas in the oil, you also have a float issue.

Petcocks CAN be rebuilt if you're careful and patient: http://xjbikes.com/Forums/viewtopic/t=25058.html

But your floats need attention too. You may just have one way out of adjustment or hanging up; or crud in the seats.