FUEL IN CRANKCASE?

HI ALL WENT TO CHANGE OIL ON BIKE AND SMELLS LIKE GAS IN THERE. WHAT TO LOOK FOR WHERE TO START? GAS VALVE WORKS FINE. ALWAYS LEAVE VALVE ON NEVER ON RES. ALSO HOW TO FLUSH OUT CRANKCASE, ANY IDEAS? BIKE HAS 9000 ORIG. MILES. ALL STOCK ORIG.



THANX JIM.

1. Always shut off petcock.
2. Could be float level in carb, but unlikely if you have had the bike for a while and haven't mucked with the float level.
3. Always shut off petcock, change the oil, keep yer noise on it for a few miles and see if it occurs again.

Oh, and Jim, just a heads up. It's consider polite to not use all CAPS as it is the equivalent of yelling.

Does the bike have a vacuum petcock or a just a mechanical on/off/reserve?

sorry doubledud hit caps lock. bike has vacuum petcock. sorry for dumb question but what is off? valve has on/primary/res.

You'll probably ned to drain the tank to inspect the petcock(fuel control valve) for tears/holes in the diaphram.

This E-10,E-85 and soon E-15 gas/alcohol mixes are tough on fuel system rubber pieces.

thanx mfolks, will look into that good info.will post what i find soon

thanx jim.

is the bike stored on the center stand or side stand,it sounds like a bad petcock and weak or scored float valve needles

Would change oil and filter before again running engine.

And also assure overflow circuit is fully functional in each carb. Sometimes difficult to clean.

Only takes one obstructed overflow circuit to result in fuel admission to crankcase. Should flow freely from top of inlet tube inside float bowl all the way to exit underneath the bike.

Also determine reason fuel is rising above spec fuel level, and take corrective action.
Often a leaking float valve (worn or dirty), or sometimes a float issue.

Ideally, perfectly functioning carb should not allow fuel level above spec even with petcock permitting free flow into carb.

Good Fortune!

bike is on center stand thanx for info.


jim.

patton the man who shall remain faceless is 100 percent correct. if the bike is stored on the center stand i would definitly look at doing both the petcock and float valve assemblies. the spring in the float valve can weaken over time.

May be just my different carbs but even with new float needles and a rebuilt petcock my carbs will still overflow a bit if I leave the petcock on Prime. I guess my little float valves are just not strong enough to hold back the pressure of all that gas in the tank

So.... I always have the petcock (vacuum petcock) set at On... and no problems

Your bike has a vacuum petcock which means that there is a diaphragm in the petcock. On one side of the petcock there is a valve that can let fuel in and out the other side. this side is in constant contact with fuel. On the other side is a spring pushing on the diaphragm trying to close the valve. On this same side there is a hose going out to the intake of the motor. when there is vacuum in the intake (motor running) it opens that valve and lets fuel flow into the carbs.

So when the petcock is "on" it is just allowing the fuel to flow only if there is vacuum to it. "Res" (reserve) is the same thing except it takes fuel from lower in the tank. "Pri" is prime and this bypasses the diaphragm completely.

Just a little refresher course on petcock operation.