my moped is back fireing whenever i take off? and when it goes faster. i changed the spark cleaned out everything i dont know what i should do to fix it? its a 1979 tomos bullet. it didnt used to back fire. is it my float?
Adjust your timing.
If your moped is backfiring your timing is probably a little too advanced. As your points wear away they can cause the gap to occur a little sooner and therefore advance your timing to the point where you get backfiring.
This could be symptomatic of a bad condensor which would cause arcing across the points and possibly deteriorate them faster --inpect them for burn marks, wear, or pitting. If they are damaged you should replace them.
<a href=" http://www.mopedarmy.com/resources/articles/10/">Fred's guide</a> has all kinds of information about this procedure. Read the section about timing.
Re: back fireing?:(
If it is backfiring through the carb, Chris is probably right. If it is backfiring through the exhaust, Chris still may be right, but also check for air leaks between the carb and the engine. Spray a little carb cleaner around these joints and see if the engine note changes (while idling).
Also, check your plug wire, cap, coil and other electrical connections.
I had the same problem
I had the same problem with me 1978 Puch Kromag. The spark plug got very old so i decided to replace it. It ran ok for the first fef miles, but then it started backfiering. Turns out that I got the wrong kind of plug. I did some research on the net and ordered the right one. It ran perfectly...until my problem...but that's a whole other story! (read about it...it's called "Now I've done it!! DAMMIT!!")
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