Fuel Shut off

I hava a 1983 Yamaha Maxim 650.... The petcock has 3 positions "ON", "PRI", and "RES" how am i able to stop the fuel from flowing?

 

the fuel tap is vacuum operated and should not allow fuel to pass in the on or res position when the engine is not running, if it does it is maybe full of crud stopping it seal properly or the rubbers have perished and failed

 

is there any way to run the bike dry?

 

sorry dont totally understand what your wanting to do, are you wanting to empty the tank to take it off?

 

no i would like to get rid of any fuel in the system while leaving the tank full

 

On position won't run the tank dry (unless you don't have your in-tank filter in place which sets the res level), you can run it dry on prime or res.

 

unhook the fuel and vac lines (petcock on ON or Prime) and run the bike till it dies will leave the tank full and the rest of the system empty

 

depends a little whether the tap holds or not, you could pull the hose off the tap but be prepared that it may still flow fully, if it does pop the hose back on, my tap doesnt hold so I have a small length of hose ready that has one end plugged with a bolt and hose clip and swap them over quickly. drain the float bowls and let gravity do the rest with the open hose you have pulled off the tap

 

Assuming the petcock is working correctly, you can put it on RES or ON, and disconnect the vacuum line on the back of the petcock. Plug the vacuum line so the bike will idle/run correctly. Since the petcock operates off the vacuum in RES and ON, no gas will flow to the carbs. Crank it and let run until it dies. If you do get gas flowing with the vacuum line disconnected and the petcock set to RES or ON, then you have a problem with the petcock. ( Remember. PRI allows gas to flow without the vacuum and is used to initially refill the carbs after working on them or running out of gas.)

 

Here's one more tip, open the bowl drain valves, and spray your favorite brand of carb cleaner thru the drain hole and let it drain out, then if you have a compressor, blow some air into the drain to evaporate any residual gas/carb cleaner. And if you're really dedicated, pull the tank, and carb hats and spray down into the emulsifier tube.

 

You CANNOT "dry out" all traces of fuel in the carbs; the less there is left behind the more likely it will turn to varnish.

If you're talking about storage, the best practice is to use a gasoline stabilizer like Sta-Bil, run the motor until the stabilized gas has had a chance to fill the carbs, and leave it.

DRAIN the carbs before re-starting the bike, and allow them to fill with fresh fuel. But if you try to store them "dry" they WILL varnish up.