Does your fuel return valve have a lever that pushes a pin into the valve with throttle on? Is there an adjustment for the lever? The fuel return valve has a diaphragm inside. Are you confident that it is working correctly?

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1962 220Sb ~ The Emerald Bullet http://www.youtube.com/watch?v=hx6tN1W48_o
1957 Ponton 220S
2001 S600 Daily Driver
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