Join Date: Sep 2003
Location: Auckland New Zealand
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By now you have probably found the problem but here's a quick fix that often works for this type of problem.
Take off what you need to get to the inlet of the carb - run the engine up to a reasonably high RPM and then while holding the throttle open, block the airway (I try to use the palm of my hand).
The vacuum has to be drawn from somewhere and often it will draw bits of rubbish through the main jet and clear it. If it doesn't work, you haven't wasted too much time.