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Author Topic: Displacement Calculator-or too much time on your hands. :)  (Read 5536 times)

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Offline MCRider

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Displacement Calculator-or too much time on your hands. :)
« on: January 19, 2009, 02:44:37 PM »
http://www.nightrider.com/biketech/calc_displacement.htm

So my 67mm pistons in my CB750 stroke of 63mm = 888cc.

Though the marketers often call it 900cc.
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Offline Terry in Australia

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #1 on: February 01, 2009, 01:32:21 AM »
Damn you Ron! Now I know my 72mm pistons are only 1026cc! >:(

Oh well, I do have some Suzuki GS1000 Wiseco 76mm super high comp that'll take my 750 to 1143, ha ha! ;D

Does anyone know what the stroke length of a 550 is? Cheers, Terry. ;D
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Offline 6pkrunner

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #2 on: February 01, 2009, 04:08:31 AM »
But Honda has lied to you more. Calling a 736 a 750 is exaggerating by 1.9%. Calling an 888 a 900 is only a 1.3% lie. ;D
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Offline malcolmgb

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #3 on: February 01, 2009, 05:46:37 AM »
I wrote an Excel spreadsheet file for this a couple of years ago at
http://forums.sohc4.net/index.php?topic=8365.msg77500#msg77500
maybe an idea to create a stand alone Visual Basic version now.
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Offline moham

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #4 on: February 04, 2009, 05:52:49 AM »
Quote from: Terry in Australia on February 01, 2009, 01:32:21 AM
Damn you Ron! Now I know my 72mm pistons are only 1026cc! >:(

Oh well, I do have some Suzuki GS1000 Wiseco 76mm super high comp that'll take my 750 to 1143, ha ha! ;D

Does anyone know what the stroke length of a 550 is? Cheers, Terry. ;D

Bore: 58.5
Stroke 50.6
Dis: 544cc

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Offline Terry in Australia

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #5 on: February 05, 2009, 01:29:14 AM »
Thanks Mo! ;D

Edit: Ooooer, so 61mm pistons in a 550 only take it out to 591.75cc's? So much for the HAINDST "605" kit............  :P
« Last Edit: February 05, 2009, 01:37:32 AM by Terry in Australia »
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline MCRider

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #6 on: February 05, 2009, 06:33:17 AM »
Quote from: Terry in Australia on February 05, 2009, 01:29:14 AM
Thanks Mo! ;D

Edit: Ooooer, so 61mm pistons in a 550 only take it out to 591.75cc's? So much for the HAINDST "605" kit............  :P
marketing is such a weird thing. 605 sounds so much better than 591. Honda's Cb350 twin was a 325. Things that are $19.95 are so much cheaper than $20.  ;D
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Offline Soos

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #7 on: February 05, 2009, 07:56:36 AM »
cb750 is 736cc, cb650 is 627cc...


If it looks pretty, rolls off the tongue might just get another customer.... Advertizing folks start this stuff.


l8r
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Offline moham

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #8 on: February 05, 2009, 09:55:48 AM »
Quote from: Terry in Australia on February 05, 2009, 01:29:14 AM
Thanks Mo! ;D

Edit: Ooooer, so 61mm pistons in a 550 only take it out to 591.75cc's? So much for the HAINDST "605" kit............  :P

Yea, but a 550 with a 650 crank and 64mm bore is 718cc, just ask paulages...or would that be a 750??
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Offline Terry in Australia

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #9 on: February 05, 2009, 11:22:27 PM »
Ha ha, well I think I'll call my 1026 a 1060 anyway, hell if old Soichiro's pants never caught fire, I reckon I'll be safe! ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Soos

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #10 on: February 06, 2009, 05:13:27 AM »
Quote from: moham on February 05, 2009, 09:55:48 AM
Quote from: Terry in Australia on February 05, 2009, 01:29:14 AM
Thanks Mo! ;D

Edit: Ooooer, so 61mm pistons in a 550 only take it out to 591.75cc's? So much for the HAINDST "605" kit............  :P

Yea, but a 550 with a 650 crank and 64mm bore is 718cc, just ask paulages...or would that be a 750??

Nah, thats a rocket with wheels!
I'd wager good money he would beat a stock 750 in a race any day.

:)

Every time I look at his bike, i'm awed...


My favorite so far(dreaming I guess) is 65.5mm pistons in a 650 makes 752cc's



l8r
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Just think to yourself what would Alowishus Devander Abercrombie do?
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Offline Terry in Australia

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #11 on: February 07, 2009, 02:28:43 AM »
Quote from: Soos on February 06, 2009, 05:13:27 AM

I'd wager good money he would beat a stock 750 in a race any day.

l8r

Geez you'd hope so mate, with much less weight than a stock CB750, only 18 CC's less, Mike Rieck head, Megacycle cam, CB750 carbs, etc etc, it'd be a dismal failure if it didn't!

What sort of BHP (and more importantly, torque) figures is that rocket ship producing? It would be more interesting to put it up against, say, Mike's own "Million dollar CB" with 96 BHP, that would be a way more interesting comparison, eh?

I've just torn down a CB550 engine to install the "605" kit, and I must say, I was impressed with the cam chain tensioner assembly, very "trick". Cheers, Terry. ;D

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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline sangyo soichiro

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #12 on: March 02, 2009, 11:03:00 AM »
If you're really bored (or simply curious), and you want to do this calculation by hand, here's how:

(Using the numbers from the original post.)
Quote
So my 67mm pistons in my CB750 stroke of 63mm = 888cc.

Since we want cubic centimeters (cc) as the final unit, we can either convert mm to cm first, or convert cubic-mm to cc last.  I prefer to convert first in this case.

There are 10 mm in 1 cm:
bore (piston dia.):--> 67 mm = 6.7 cm
stroke:--> 63 mm = 6.3 cm

We want the volume of the displacement.  This is the volume of a cylinder, the formula for which is
volume = piston cross-sectional area * stroke.
("*" means "times")

The cross-sectional area of the piston is the area of a circle:
Area = pi * radius-squared, or A = 3.1415 * r2.


Putting it all together gives
displacement = 3.1415 * (bore/2)2 * stroke * number of cylinders.

Example:
Using the above numbers, we get

displacement = 3.1415 * [(6.7 cm)/2]2 * 6.3 cm * 4
                  = 3.1415 * [3.35 cm]2 * 6.3 cm * 4
                  = 3.1415 * 11.2225 cm2 * 6.3 cm * 4
                  = 222.1160 cm3 * 4
                  = 888.46 cm3 (or cc's).

Good old geometry.   :)

Notice the units work out correctly.  This is one trick to doing calculations; carry the units throughout the calculation, and if the final units aren't what they should be, then you know to look for a mistake.



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Offline Terry in Australia

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Re: Displacement Calculator-or too much time on your hands. :)
« Reply #13 on: March 03, 2009, 02:47:19 AM »
Well I wasn't that bored before hand, but I am now..............  :P ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)
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