8 replies to this topic

[rusty789]

If a 998cc engine has been bored out 60thou, what size does it make it?

Stupid question maybe but im a noob!

And i did search, if the answers is right under my nose sorry!

Edited by rusty789, 11 October 2009 - 12:09 PM.

[shorty]

1046 maybe

[cookie4343]

Yep im pretty sure shorty is right in thinking it's 1046.

[benpopham]

so what would 998 +40thou be?

Ben

[rusty789]

So twin 1.25" su carbs would suit this okay?

[Ouster]

We have a FAQ section for a reason! Check here for what bore makes what size:
http://www.theminifo...?showtopic=8736

[Pauly]

How do you calculate cc's, maths was never my strong point .

Paul.

Edited by Pauly, 11 October 2009 - 01:28 PM.

[rusty789]

We have a FAQ section for a reason! Check here for what bore makes what size:
http://www.theminifo...?showtopic=8736

As said i did search but couldnt find what i was looking for! But thanks for that chart..

[Ouster]

Volume of a cylinder is Pi*radius^2*height
In the context of an engine, this is Pi*(bore/2)^2*stroke.
This gives the volume of one cylinder. So times it by 4 to get the formula for the total cc: Pi*bore^2*stroke

Remember to work in centimetres (cc = cubic centimetres), or convert at the end, and you can't go far wrong.

e.g. Standard 998 has a 2.54" bore, and a 3" stroke.
If you're overboring by +40 thous (i.e. 0.04) then the bore will be 2.58". The new total cylinder volume will be pi*2.58*2.58*3 = 62.7 cubic inches.

1" is 2.54 cm so one cubic inch is 2.54 cm x 2.54 cm x 2.54 cm = 16.39 cubic centimetres

Times the answer of 62.7 by this to get the total cc: in this case = 1028 cc.

Edited by Ouster, 11 October 2009 - 01:54 PM.