.75 over =?

[NTPracing22]

my 250r is bored .75 over. what cc's would you say that is? about 257....260? also what would a 265cc be.... .80 over? i just need to know so i don't go over my class limit. thanks a lot guys.
#22

[seven]

From what i have read 80 over is at a 265.

[Crawl69]

I can't remember the size of the stock cylinder bore, but yours is 0.075 over. So you multiply 0.075 by 25.4 to convert it to mm. Add that to the stock bore, find the area of the piston and multiply it by the stroke.

0.075*25.4=1.905mm
1.905+(stock bore)=x
x*stroke of piston=displacement (cc)

[NTPracing22]

alll i know is its 246cc. so i'll just pretend its some big number thats really fast. lol, jk

[Crawl69]

I forgot, take the diameter of the piston and multiply it by 3.14. whoops

[250EXking]

70.5 is about 20 cc

[XANDADA]

Your at 259.56cc;)

[250EXking]

how do you calculate the CC.

[OutlawEX]

Well i know a 416 is bored 80 over so id say u at around 265cc

[Crawl69]

take the diameter of the piston, square it and multiply it by 3.14. Then divide that number by 4. Multiply that by the stroke of the piston and that is the size of the cylinder. Just remember, if you measure the diameter or the stroke in inches, it needs to be converted to mm by multiplying it by 25.4. Here's a better way of looking at it:

(Piston diameter (in mm)(squared)*3.14)/4= area of piston in mm squared

(area of piston)* (stroke of piston (in mm))/10=size of cylinder (in cc)