So here it's...55cc

Ben Van Zoest /

Measured the bore and stroke displacement plus head cavity volume:

38 x 3.14 x 43mm = 51 + 4 = 55cc. What now?

Re: So here it's...55cc

some folks measure stroke from when the piston is just opening the exhaust port. Head cc is not included in displacement

Re: So here it's...55cc

Displacement: Pi x Radius squared... not Pi x diameter... x stroke.

38mm bore... 19mm radius... 19mm = 1.9cm

43mm stroke... 43mm = 4.3cm

1.9 x 1.9 x 3.14 = 11.3354

11.3354 x 4.3 = 48.74222cc

38mm bore / 43mm stroke = 48.74cc displacement

Re: So here it's...55cc

math makes my head hurt...quit it...lol, if it runs ride it!

Re: So here it's...55cc

First do your math right. Then, put it on the engine and see how it runs. My guess is you will have lost lots of compression, resulting in degraded performance and/or a non running engine.

So, I can only assume your next question could be "what do I do about the compression loss?".

One thing I can think of is forced induction. Pretty sure thats difficult to do on a 2 stroke. Other than that, maybe a different fuel which compresses differently, dont know what fuel to recommend though.

Re: So here it's...55cc

Ben Van Zoest /

I feel cheated, however adding the convects head volume it comes out to a mere 50cc

Sorry It's been 60 years since garde school, one tend to forget the proper formula,

V = TT r2 h

Re: So here it's...55cc

that would be GRADE, not garde

seems like your spelling is off as well

I would work on the basics, math and spelling, before trying to cheat cc's out of a top end

you will get much more power and speed, easier, from things like porting, air and fuel flow, compression raising, port timing etc. than from trying to add displacement on a stock moped

Re: So here it's...55cc

Ben Van Zoest /

One problem is eye surgery, mucked up an eye very bad things are out of place, like looking at the formula area

where r 2 to me twice r not r to the second power.

The typos have something to do with severe arthritis, don't be so critical I am doing the best I can.

Re: So here it's...55cc

so when it all goes together, give us the compression test numbers.

Re: So here it's...55cc

Ben Van Zoest /

Will do, hopefully coming weekend. I need the big drill to cycle the motor.

Re: So here it's...55cc

Force induction hmmmmm. A 120 volt drill, small squirrel cage blower and a really long extension cord.....

Re: So here it's...55cc

Hmm, I think most 120VAC drills still only use like a 36V DC motor...

But yeah lets not start another turbo thread.

But I will say, that generally when people use forced induction, they lower the compression.

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