What is the FA50 Gap Size?

I've got the new spark plugs and the gaping tool. I've also learned how to gap a spark plug. All I am missing now is the appropriate gap size for the spark plug, because I do not have any manuals for the moped.

I have heard from one source that .6mm-.8mm is the suggested size, but I would like to be 100% positive before gaping it. Every little bit will help it's performance so...


Re: What is the FA50 Gap Size?

that sounds about right .. most moped manuals, if not every one, will specify something around 0.7mm (0.025 to 0.03 inch). The specification is for brand new bikes as delivered from the factory using the recommended brand of plug / heat range, etc.

But engine wear, different fuel:oil ratio or oil type, alternate plug brand, or lots of other things may suggest a slight plug-gap adjustment.

before you ask..

you could mess with plug gap to find the ideal setting for your bike in it's current condition but it's not easy to do correctly.. the bike should otherwise be in perfect tune.. nothing wrong.. and then you need a way to carefully measure performance while trying different gaps.

start near the smaller end of the range and increase gap by maybe 0.002 inch and test at top speed .. At some point the bike will begin to lose power.. Then, you'd go backwards, closing gap by 0.002 .. The resulting gap is just about ideal.

If you're gonna do it, do it only after a very thorough tune up including a de-carboning of the combustion chamber, adjusting ignition timing.. everything. And then keep it in tune or the gap will be wrong.

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