Greetings,

Just out of curiosity, I wanted to convert the size of ATV engines to cubic inches (some of us are still grounded in the days when car engines were measured in cubic inches and will never get used to the metric system). I found a table that gave a conversion factor of .06102 -- that is, multiply the cc number by .06102 to get cubic inches. Is this correct?

This makes a 450 cc engine a 27.46 ci engine. Or a 432 cc is really a 26.36 ci. Sound right?

 

Sounds about right, Dr. Rod! A 500 cc motorcycle engine is 30.50 cubic inches, nominally--does that check out?

If you get stuck again, remember 2.54 cm./in.

A little long division and/or multiplication, and voila!

I'm sending you a conversion chart separately.

Tree Farmer

 

Divide the number of cc by 16.4, A 400cc engine is 24.39 cubic inch.

 

How about an equation on how to figure out how many cc's I am. My 86 R is bored .050 over. Would that be a 67.25mm bore and a 72mm stroke?
ERIC

 

Try 1/4 (Pi)(Diameter)(Diameter)(Stroke). I think that works.

Engineer feller down at the mill claims with calculus, you can calculate the increase (he called it, "delta," I think) only an overbore gives over the stock displacement, but he began using terms I didn't understand, like "antideriviative" and such; he lost me early in the discussion.

Tree Farmer

 

Treefarmer, what do you mean by dia X dia? Bore X ? Shouldn't the stroke be in there somewhere? Also, I thought you know ALL the big words!(antideriviative)
ERIC

 

Right, retro, multiply the whole thing by "stroke," I've edited the original. Yeah, diameter's the same thing as bore. And, antiderivative? Anything like an "integral?" Where's Isaac Newton when you need him?

Shoulda paid attention in school, I know!

Tree Farmer

 

Greetings,

While the calculus in "intgral," I believe the unit is "integer." But I'm not sure. Just wanted to keep moving this forum to higher and higer levels.

Oh yeah, my quad can beat your quad.

 

I still can't figure it out. Am I mental? Don't answer that!
So you are saying 1/ 4pi*66*66*72 or .25*4pi*66*66*72? (Stock bore=66mm stroke=72mm)
Either way, I don't get anything close to 246cc.
ERIC

 

I got it! I went to www.macdizzy.com/sixtynine.htm and Rick had a link to some math stuff.

Here it is for a stock R:
Bore=66mm
Stroke=72mm

The equation for volume(in cubic centimeters) in a cylinder is:
pi*r^2*h
pi=3.14159
r=66/2=3.3cm
h=7.2cm

3.14159*3.3^2*7.2=246.32578 cc's

As far as boring out an R with stock stroke goes, for each .010" (.25mm) over piston you go up, you add roughly 2cc's. Here is a list.

Bore CC's
---------------------
stock bore 246.33
0.25mm 248.20
0.50mm 250.07
0.75mm 251.96
1.00mm 253.85
1.25mm 255.74
1.50mm 257.65
1.75mm 259.56
2.00mm 261.48
2.25mm 263.41
2.50mm 265.34
2.75mm 267.28
3.00mm 269.23