650R idle speed problem

Hallo All,

I have just bought a 2001 XR650R and I'm having a problem with it.

It stalls at idle speed in a weird way.

I start it when it's cold with choke fully open then warm it up and close the choke. The engine works rough at idle speed for a minute then the speed increases without any assistance (I don't touch anything) and stalls.

When it stalls ones I can not start the engine without choke open and if it starts it just speeds up and stalls again.

What I have checked already:

- the filter in the tank is clean.

- carburetor is clean.

- spark plug is covered with black deposit

- engine runs at idle with the fuel screw completely closed.

Appreciate for any advice as my right leg is too tired to experiment .


What size are the jets? Has the engine been "uncorked"?

If it runs with the fuel screw screwed all the way in that is a sign the pilot jet is too big.

It is not a corcked bike as I bought it from Japan.

Pilot jet is 65 and main is 175

What's the ambient temperature? 65 seems like a small pilot for winter conditions (though Hawk is right about the mixture screw). Weird.


It could be that your air cut-off valve is acting up. It leans out the mixture when you decelerate to lessen the chance of backfire. Revving up just before it dies may indicate a lean condition.

Or the bowl could be starving for gas. Make sure the float goes up and down freely. Same with needle.

Make sure the vent hose that attaches to the filler cap is O.K., too.


It was a petcock problem!

Thanks a lot for your help :thumbsup:)))

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