Fuel Mixture 66cc cylinder on a 48 cc crankcase and crankshaft - runs too rich

lazylightning@mail.r

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Hi Everyone!
A fellow I know put a 66 cc cylinder and piston onto a 48 cc engine base. It's running way too rich. The plug needs to be cleaned all the time with massive buildup. The same carb with the same settings ran normal with the 48 cc cylinder and piston.
Could the narrow space of the smaller 48 cc crankcase and crankshaft be actually choking off the air flow and pulling more fuel from the carb with the larger volume cylinder?

Thanks,
Paul
 
if he actually did what is claimed, widening the top of the cases to accept the larger cylinder should have narrowed the transfer port passages to about nothing

first thing that comes to mind is "WHY?"
 
plug fouling is a result of too much oil, too cold a plug, or irregular spark.

there would be about 3mm of transfer port left if he actually did this
 
impossible.
the stud spacing for the cylinder is different (longer) for the 66cc than for the 48cc.
I was able to put a 60cc cylinder on without modification so maybe that is what he did.
 
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