Running Rich

I think that my moped is running rich. When I take off the air box (not the filter) on my carb, I get about 5-6 mph higher top speed. I tried cleaning the carb thoroughly, and I'm jetted at only #48, so what might be causing this problem? I already know that the bike has low compression, could that have something to do with what I'm seeing here?

Also, until I can fix the problem, is it ok to ride without my airbox on? I still have the air filter in, just not the box.



P.S. If it makes a differece, my engine is a Franco Morini M01 with a 14/12 Dellorto carb.

Re: Running Rich

removing the box means less air restriction, and allows a leaner mixture .. and lean is where the power is. It's understandable that top RPM and therefore top speed would increase.

Lean is also where the heat is and where things can get too hot, possibly damaging the engine., so one must be careful..

if i were you i'd reinstall the stock box for the time being and learn about plug chops.. and how to "read" plugs... and how to tune WOT (wide open throttle) air:fuel mixture.

low compression also contributes to higher RPM (less energy is wasted compressing the mixture) .. however, if it's due to a mechanical fault, low compression readings are nothing to take lightly.

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