I'm talking to armyman, or anyone that knows about details.
Here's my question:
How do I get the ccs of an engine knowing bore and stroke?
I thougt I could simply do "bore X stroke = cc". But no. Is the bore the disc area, or the diameter or radius? Do I have to consider the size of the "domes" ?
For multicylinders engines, is the bore for all cylinders or do I have to multiply it?

Sounds stupid and easy, but I get 346cc instead of 347cc for me shee (that's no real big deal) but for the big 500cc single MX...I don't remember, but I was pretty far from 499cc...

Someone smart help me!

 

Try (bore)(bore)(stroke)(pi)/4.

Or, (pi)(bore/2)(bore/2)(stroke).

Diogones, where are you when we need you?

Tree Farmer

 

Sorry, TF; my lamp was dim, I missed that one; I'm turning the wick up.

BTW, agree with your math formulae. (Please check spelling of my name.)

Diogenes

 

Zorro, take armymans name out of your post or atvbbs will. I found out the hard way!

 

go to macdizzy.com, i believe he has the formulas on the site

 

Yes, I saw that, but the easy way. atvbbs sent me an email saying not to use personal...etc and said he had modified my title to be "the way it should". Nice. He could have simply deleted the post. He took the long way and edited my title to make it better, which is cool. Thanks Moderator!

 

They work. So bore is the diameter between cylinder walls? That sounds possible (and I get to your same equation).
Boy do I have the feeling of being a dumber...heard these things for years, and learning now what they are exactly...weird!
Thanks guys.
Armyman...too late!!!ahahaha

 

I just wanted to point out that the formulas listed by Tree Farmer are correct only if the bore and stroke are entered in centimeters (to obtain cubic centimeters of displacement). Most of the time the bore and stroke are listed in mm and the same formula can be used but the product must be divided by 1000 to convert cubic mm to cubic cm (cc). I am sure this was evident to those that posted reply's, but may not have been clear to those that aren't used to conversions or working with the metric system.

1988 TRX250R with 350X motor bored and stroked to 500cc. Quad has every accessory available to set up for racing motocross.

 

the easiest fomula is(in mm)
bore X bore X stroke X .0007854
Example(250cc)66 x 66 x 72 x .0007854 = 246.
stock 250R