80cc engine?

Well, what exactly is the diameter of the piston? Did someone say above that it's the same as a 66?

Here's an old thread of mine where I asked for the diameter of a 66- the answer I got was 47mm. The 50cc piston is 40mm.
http://motorbicycling.com/showthread.php?p=327695

I'm assuming if there is ANY piston difference, that the stroke is still the same length.
An 80 would have to have 30 percent larger piston diameter than the 50c.c. motor?
or 52mm (?).
 
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This piston picture looks familiar- a few years back there were in fact three sizes of 2 stroke engines out there selling- I think the middle one was actually called a 58cc motor, and this picture looks exactly like the one I saw here several times comparing the pistons- maybe that's where it's from-

anyway I think the diameter has to be 30 percent larger
 
I just measured the relative sizes on my computer, and the 50 cc piston is about 28 mm in diameter- so 30 % more would be another 8.4 mm (3 x 2.8mm)
so 28 mm plus 8.4 mm = 34.4 mm- which indeed is roughly the relative size in the photo-

unless it is in fact a DIFFERENT piston in the motor than in the photo- it sorta looks like it could be genuine.
 
You are correct sir! "50cc" "60cc" and "80cc".

Which were really 47cc, 58cc and 66cc I believe.....now I've got a head ache.

Anyhow, the seller never responded to either of my inquiries, which doesn't sit well with me if I were to consider buying one, which I am not.
 
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To get true 80cc the bore would have to be
50,4mm in combination with a 40mm stroke crankshaft and
51,7mm with a 38mm crankshaft.
I've never heard about other strokes in HT engines.

Multipaul
 
That engine might be as good as any other but what would bother me if I had bought one thinking it was something new when it was infact a basic ht. The older I get the smarter my Dads words seem, "son if it sounds too good to be true it probably is".
 
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