Fuel petcock positon for OFF??

HappyHunter

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Hi,
I bought my first xs last fall. A nice 650, no title, no front brakes. The mystery is how to turn off the fuel. It has positions for ON, RES and PRI. How do you turn it off???

Thanks,
Steve
 

5twins

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You have a vacuum powered petcock. It only flows fuel (or should) when the motor is running and sending it a vacuum signal. There is no "Off" position. "ON" and "RES" should flow no fuel with the motor off. The "PRI" position stands for Prime. This bypasses the vacuum operated part of the petcock and just flows fuel in a normal manner like an old fashioned On-Off petcock. It will flow at all times, motor running or not. Normally you use this position to quickly refill the carbs after draining or maybe if the bike has sat a long time and fuel levels in the carbs have gotten low due to evaporation.
 

suntosh

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How long to run on PRI before turning it to ON ? Today I had to keep it on PRI atleast for 2 miles before turning it to ON
 

jpdevol

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Normally you use this position to quickly refill the carbs after draining or maybe if the bike has sat a long time and fuel levels in the carbs have gotten low due to evaporation.
Unless there is an issue with the carbs or petcocks, you should not have to use "PRI" at all. Only after carbs have been drained or stored.
 

5twins

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It should only take 30 seconds or so for the carbs to refill.
 

suntosh

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Unless there is an issue with the carbs or petcocks, you should not have to use "PRI" at all. Only after carbs have been drained or stored.
Sir I just had the mechanic rebuild the Percock . Do you think he drained the Carbs and thats why I had to switch it. Just brought it back . How do I test if there is a problem ?
 

650Skull

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Using the bike every day or even longer periods between rides, having the petcock lever left to the on position it should never have to be used on prime. ...........at least mine didn't

Prime is only used if the bowls are empty, or partially empty, or if you have a leak from the bowls and evaporation is occurring, then you have a problem that needs to be fixed
 

jpdevol

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It's difficult to see the petcock inlet inside the tank, but anything over perhaps 4" of fuel inside tank and it should flow in "ON" position -below that "RES" until almost empty.
 

gggGary

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Depending on temps a week or two is enough to drop fuel levels in the bowls IF your petcocks aren't leaking ... Check that all your vacuum lines fittings clamps are snug no cracks or crimps.
 

ckahleer

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Test the petcock.
Put petcock in on position.
Remove fuel line at the petcock.
Renove vacuum line at the intake manifold.
Suck on the vacumm hose. Fuel should flow out of the petcock when sucking.
Put petcock on reserve. Fuel should flow out of petcock when sucking.
Put petcock on PRI. Fuel should flow without sucking.
 

suntosh

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Thank you I mma try all these. Should I be repainting the innards of the tank. I see quite some rust. Or do you just live with it.
 
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