Vintage Dirt Bike Q & A

I noticed that fuel is not making it down to my carb on my mr250. When the bike is running it allows a small amount of fuel to trickle down. I know my tank is clean, my valve is clean, and I am getting air into the tank through the breather cap. I think it may be the float needle valve. Is that common on these bikes?

Thanks

Take the float bowl of your carb in situ and work the float valve with your finger. It should be real clear when the valve is open that enough fuel is coming through. If any less than a good gush, work backwards checking for blockages. I am not familiar with your bike specifically, but remember that some Suzukis in the early '80s had fuel taps that could not flow enough fuel at high revs causing lean conditions and siezures. Eric Gorr's book talks about drilling out the passages in the carb so you are sure that the tap and the float valve are the only pieces influencing the amount of flow. Unless you are very sure of the condition, I would replace the needle, needle jet and complete float valve on old carbs as a matter of course.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF