This is a symptom of a lean mixture.
Either you have restricted fuel flow (possibly due to a blocked jet or water in the float chamber), or an air leak at the manifold gasket.
Before you start taking it apart, check that the tank has fresh fuel, then remove (or at least slacken off) the drain screw in the float chamber. Allow enough fuel to drain to be sure the fuel line is completely purged (a drop of water will effectively block the main jet). Tighten screw and test.
If no luck, you will have to strip & clean the carb.
phil_saunders@bigfoot.com
Phil Saunders, August 2008
