Need to know the true engine displacement for my 110

**hondaATCman** · 10-17-2003, 09:41 PM

I never understood the mathmatics of knowing your engine size after you bore it out. I had my ATC 110 (which is actually 105 cc) bored out .30 over. Can anyone tell me the actual displacement of it now? I would also like to know how many cc's you gain per .10 overbore. Thanks

**200Xtreme** · 10-18-2003, 08:19 PM

You have to know bore, and stroke sizes to calculate displacement.There is not a certain size displacement gain per .010" bore. The larger cyl. you start with, the larger gain you will see per the same oversize.(ex. .040" overbore will be more increase than a .010" overbore x 4.)

**wizzard** · 10-18-2003, 08:34 PM

look at the specs. area on the home page and it'll tell you the bore and stroke. i know the formula but i have to use a convrter i have at work to go from mm to inches back to cm3. i'm stupid like that

**Howdy** · 10-18-2003, 08:52 PM

Originally Posted by wizzard

look at the specs. area on the home page and it'll tell you the bore and stroke. i know the formula but i have to use a convrter i have at work to go from mm to inches back to cm3. i'm stupid like that

While I don't know the conversion for cc's I do work with metric and know this:
The metric to standard conversion is to divide mm by 25.4 = inch. Example: 50.8MM / 25.4 = 2.00 inchs.

Now to go from inchs to MM take the inches and times it by 25.4 = MM Examble: 3.00 inches x 25.4 = 76.2 MM

Maybe this will help out.

Howdy

**marc92040** · 10-21-2003, 07:28 PM

Assuming your using the stock stroke the displacement for .30 inch over will be 138.1CC this is assuming you are using a true 59.6mm piston

if your using a stroker crank (8mm is usual) the displacement is 160.4

you have to convert the bore and stroke to inches to get accurate results.

The formula 3.14159265(Pi) x (Bore/2)2 squared x Stroke x Cylinders

to convert MM to inches multiply MM by .0393699

than use the formula
here is an example from a stock 110 (105.1 cc)

bore 52mm (52 x .0393699= 2.047235 inches)
stroke 49.5 (49.5 x 0393699=1.94881 inches)

3.14159265(2.047235/2)[size=9]2 *(1.94881)*1 /.0610368 = 105.1cc

3.14149265(1.0236175 * 1.0236175)*1.94881*1

3.14159265(1.047793)*(1.94881)*1 =6.41497 <-- is cubic inches

6.41497 / .0610368 = 105.1009cc

this result will be in Cubic inches divide that number by .0610368 this will give you acurate displacement in CC's

hope this helps

can you tell me where you got a .30 over piston i'm looking for one now for a stroker moter that i am rebuilding

thanks

**hondaATCman** · 10-21-2003, 07:45 PM

hey, thanks for the formula, but I gave some false info in my first post. I had it bored .030 in. over (same thing as .75mm) not .30 Sorry about that. Can you refigure my cc's for me? I'm not a math genius what so ever but I'll try your way and see what I get and check it with your answer. I got the piston from Dennis Kirk, they only have Pro-X brand (no Wiseco) but anyways they are available from .010 to .050 overbore sizes and run 68 bucks. If you're looking for a cheap place to get your cylinder bored, I sent mine off to Eckhoff's Custom Machining ( www.wesleeve.com ) . They do an excellent job boring, honing and chamfering the ports for $20. Thanks

**marc92040** · 10-21-2003, 10:10 PM

okay you should have a 52.75mm piston diameter with stock stroke (49.5)that being the case your displacemant will be 108.15cc

if you are runing the stroker crank(57.5mm) it will be 125.6

do you have Microsoft Excel I could e-mail you the spread sheet it's pretty easy to use and works for all bikes no mater how many cylinders

let me know if you need any more help

**marc92040** · 10-21-2003, 10:12 PM

thanks for the info on where to get the piston

marc

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Need to know the true engine displacement for my 110