Power User
The day begins with 3WW
ok so my question is this, my friend has a 200m he thinks borin it 2nd oversized will increas the bottem end of the bike majorly and that it will pull much better, i said no it will hardly be a diffrence not enough to feel, and then my other friend thinks borin it 50 thous over will make it a 250 ! so what i need is how to figure out the ccs of the bike
thanks for the help in fixin this confzzzelment
1985 Tri-Z-
Originally Posted by mywifeknowseverything
Got The Holeshot
Arm chair racerJust too addicted
Bore x bore x .7854 x stroke.
65.5 x 65.5 x .7854 x 57.8 = 194.7cc 191.7cc is standard
At The Back Of The Pack
Arm chair racerFirst time rider
CC's of the bike,
You're figuring the volume of ONE cylinder.
V = Pi x radius^2 x height
or an engine cylinder would be;
Volume is Pi x (bore^2)/4 x stroke. A "50 thousands" over bore is actually an increase of .050" in bore diameter.
Use these very simple formulas to solve for volume. Work them out and spend 15 minutes doing these calcutions and this will stick with you.
Also, for more calculations,
What 8-cylinder engine has a bore of 4.00" and a stroke of 3.48"? You should round up to the next full cubic inch, that's what GM did.
Studytime
Last edited by Studytime; 11-24-2004 at 07:43 PM.
Power User
The day begins with 3WW
thanks guys, i have it all hear in one of my mechnics books but couldent really make ends meat of it lol green human bout naild it for meplain and simple lol
1985 Tri-Z-
Just Too Addicted
Arm chair racerJust too addicted
something is wrong here. You have V = Pi x radius^2 x height, then go to Pi x (bore/4)^2 x stroke. Where radius = bore/4. This is wrong.
This is correct:
bore = diameter = 2 X radius or radius = bore/2
83 YT 175
85 ALT 125
Banned
The day begins with 3WW
This is the simple formula used by AMA and CRA, but in order for it to work, you have to convert the .050" into 1.25mm. Your calculations are for .50mm which is .020" overbore.
66.5 x 66.5 x .7854 x 57.8 = 200.75
Either way, boring is not a performance modification, it is a wear and tear fix, but if someone likes throwing money away for no noticeable gain, its good for the economy, anyways!
At The Back Of The Pack
Arm chair racerFirst time rider
Yes sir, you would be right. I had (B/4)^2 instead of (Bsquared/4). I'll go back and fix it.
I think it's important to understand the formula and not just know a generic sequence of numbers to multiply.
Good catch Dan.
Studytime
Got The Holeshot
Arm chair racerJust too addicted
2nd oversize is half a mm. The standard bore is 65mm so 2nd oversize is 65.5mm. That's what he originally asked. If you want to spend 5 seconds working out your cc's, do it my way. If you want to get a headache do it their way. The standard bore is 65mm + 1.25mm =66.25 which = 199.24cc
At The Back Of The Pack
Arm chair racerFirst time rider
If simple algebra give you a "headace", you have no business building a motor at all in my opinion. I'm directing that to anyone, not just you Greenhuman.
Studytime
At The Back Of The Pack
Arm chair racerFirst time rider
OH, does anybody want to take a stab at where .7854 came from?
Studytime
Got The Holeshot
Arm chair racerJust too addicted
If you can't spell headache you have no business telling everyone how to do algebra in my opinion. My people could not care less where it comes from as long as it works.
Within Arms Reach Of The Master
Arm chair racerLord of the trike
If you want really simple just get the free virtual engine calculator from http://www.virtualengine2000.com/index.htm
It's kind of nice when you figure it out, easier then doing the math.
Now if your extreamly lazy just look up the .pdf files at www.wiseco.com
They got almost everything worked out for you already.
'02 Honda 416ex - A seasoned blend of 11 herbs and spices
'04 Honda Recon - The yard machine and snow plow
'88 Honda CR250R - Another chapter in my torrid all terrain affair
At The Back Of The Pack
Arm chair racerFirst time rider
Greenhuman, you win. Your method is way better. Nice and mindless. I guess I wasn't smart enough to see the exact word in your post.
On a serious note, typoes happen when you use two hands.
Gave a good Thanksgiving.
Studtyime
Last edited by Studytime; 11-25-2004 at 11:51 AM.
Got The Holeshot
Arm chair racerJust too addicted
hey, the wiseco catalog lists the cc with the bore size
one cylinder is not enough!!
At The Back Of The Pack
Arm chair racerFirst time rider
That's even simpler to use and really clears up the confusion.
Couldn't be any easier!
Studytime
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