Larry Miller5509
XS650 Enthusiast
How do you determin the cc's after boring an engine? I bored 2nd. oversize.
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
CCing a new bore
- Thread starter Larry Miller5509
- Start date
madjap
XS650 Addict
Height times radius times 3.14 is how you get cylinder volume BUT I'm not sure if a combustion chamber area is included in overall engine size CC's or not... So, basically... I've been almost no assistance whatsoever. Sigh.
Haha, madjap, using the wrong divining rods.
This'n requires dangling a calculator from a piece of string.
If you do it in millimeters:
Bore * Bore * Stroke * Pi/4 = Displacement of one cylinder in cubic millimeters
To get it in Cubic Centimeters, divide that mess by 1000
Ex:
Bore (2nd over) = 75.5mm
Stroke = 74mm
Pi/4 = (3.14159 / 4) = 0.7854
75.5 x 75.5 x 74 x 0.7854 = 331296.2, then (divided by 1000) = 331.3cc
Thats for one cylinder. Multiply by 2 to get total displacement = 662.6cc
Compression chamber volume is not included when calculating displacement...
madjap
XS650 Addict
Good LORD, I re-read my post this am and I hope to GOD no-one EVER follows my post-feverish advice on ANYTHING! I'm not even sure cats CAN fly now! Mr. Miller; take my formula, mix it with 2Many's, take all the math, crumple it up, throw it away. THEN, take 2Many's math and use IT while stomping your good foot on MY MATH (twice)...
Larry Miller5509
XS650 Enthusiast
That's a great formula. Thank you very much. I can always depend on everyone at Xs650 for those hard questions.
We can simplify this even more.
For our 2-cylinder XS650 engines, keeping with the standard 74mm stroke, you can simply use the bore (in millimeters) squared, times the constant of 0.116239 to find the displacement.
(Bore) x (Bore) x 0.116239 = Displacement in CC's
75 x 75 x 0.116239 = 653.84 cc
Bore => Displacement
75.00 => 653.8 cc (STD bore)
75.25 => 658.2 cc (1st over)
75.50 => 662.6 cc (2nd over)
75.75 => 667.0 cc (3rd over)
76.00 => 671.4 cc (4th over)
76.50 => 680.3 cc (6th over)
77.00 => 689.2 cc
78.00 => 707.2 cc
80.00 => 743.9 cc (750 kit)
80.25 => 748.6 cc
83.00 => 800.8 cc (Crazy big)
For our 2-cylinder XS650 engines, keeping with the standard 74mm stroke, you can simply use the bore (in millimeters) squared, times the constant of 0.116239 to find the displacement.
(Bore) x (Bore) x 0.116239 = Displacement in CC's
75 x 75 x 0.116239 = 653.84 cc
Bore => Displacement
75.00 => 653.8 cc (STD bore)
75.25 => 658.2 cc (1st over)
75.50 => 662.6 cc (2nd over)
75.75 => 667.0 cc (3rd over)
76.00 => 671.4 cc (4th over)
76.50 => 680.3 cc (6th over)
77.00 => 689.2 cc
78.00 => 707.2 cc
80.00 => 743.9 cc (750 kit)
80.25 => 748.6 cc
83.00 => 800.8 cc (Crazy big)
^ Good stuff there!
I would have done it the lazy way.
680cc is 6 over = 27cc larger than stock.
6 over is 3 x 2,
27cc divided by 3 = 9cc
second over is 653cc + 9cc = 662cc.
I know lazy and inacurate
Have kept you formula for future..........thanks 2m
680cc is 6 over = 27cc larger than stock.
6 over is 3 x 2,
27cc divided by 3 = 9cc
second over is 653cc + 9cc = 662cc.
I know lazy and inacurate
Have kept you formula for future..........thanks 2m
Haha, that's in my other book, SWEG, Scientific Wild Estimated Guesses.
I use it for calculating restaurant tips...
Larry Miller5509
XS650 Enthusiast
Oh that's good
