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Old 08-03-2010, 02:41 PM
Missmichelleb Missmichelleb is offline
Motorized Bicycle Senior Member
Join Date: Oct 2009
Location: Escondido, CA
Posts: 52
Default Re: Help.. Broken Bottom engine casing.

Originally Posted by GearNut View Post
What color is the spark plug?
Always let the engine cool down completely before removing the spark plug or you risk the threads coming out of the cylinder head.
The color will show you approximately what the air/ fuel ratio is.
Black = too rich.
Chocolate brown = perfect.
White or light brown = too lean.
Silver = damage to piston and waaaaay too lean.
The downhill only part is kinda wierd. I want to say it may be chain tension related.
Which part of the spark plug am i supposed to look at for color?
I'm guessing i need to take it out?

How do you adjust the Air/ Fuel ratio?

I think it only when i'm going downhill... to be honest i was really just looking for some kind of marker for the problem because it doesnt happen all the time.. just sometimes... and at first it seemed to be with no ryme or reason, the downhill thing was just the only thing i noticed.
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