Fuel leaking from vacuum take off

[Norman AndersonParticipant]

Hi David, you’re right about the rich mixture. This is definitely running rich. It needs no choke at all when starting from cold. I haven’t looked at the fuel consumption yet, but it doesn’t appear to be great. I guess if it needs to be addressed, the only way will be to change the main jet?

[BernieParticipant]

Norman,

Can you not weaken the mixture enough by screwing in the mixture screw ?

If you have a “Colourtune Plug” you can quickly check and see the imediate effect of any adjustments although the plugs are the best long-term indicator of  a good fuel/air mix.  If you don’t have such a magic plug, I would suggest tightening the mixture screw no more than a quarter turn at a time and then running for a while before checking the plug colours.  And you will probably have to adjust the idling to maintain optimum tickover as the mixture is altered.

B……

[Author]

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