Ok what makes what 1641. 1715 etc. how do they break it down? not sure on this

piston/cyl and crank size

Try this:
plug in numbers and it will tell you what you got
Usually but not always, 1915cc and smaller type 1 is stock (69 mm) stroke.
http://davisracing.com/engine%20calculator.htm

Here is one too.
Stock stroke is 69 as Larry mentioned.
90mm piston is pretty uncommon these days.

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Gary

Turbo VW Sand Racer
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