How big is your engine after a rebore?
Hi Terry, I am often asked how big my
XS650 engine will be when it is rebuilt
so I thought this would be good to put
on the web site, somewhere. Std. bore, 75mm = 653cc +0.25mm O/S = 658cc +0.50mm O/S = 662cc +0.75mm O/S = 667cc +1.00mm O/S = 670cc +5.00mm O/S = 743cc, the standard
750cc big bore kit, resleeving
required, or Mikes XS big bore kit. +6.00mm O/S = 762cc. So as you can see if an engine
is bored to 75.50mm that makes it 662cc
which is larger than our LAMS law here
in Victoria, 660cc is the limit.
Increasing the stroke of the engine will
increase the capacity even further. Regards Daryl Hutcheon Additional information if you want to work it out for yourself. You will need to know the bore and stroke of your engine, for example a stock XS650 motor has a bore of 75mm and a stroke of 74mm. Next you need the formula to work out the capacity of a cylinder multiplied by the number of cylinders. Pi X R^{2} X H = Volume or capacity of a cylinder and our motor has two cylinders X 2 Radius(R) = bore/2 = 75mm/2 = 37.5mm or 3.75cm and R^{2} = 14.0625cm Height (H) = stroke = 74mm or 7.4cm So (22/7)Pi X R^{2} (3.75cm ^{2}^{ }) X H (stroke 7.4cm) X (number of cylinders) 2 = 3.142 X 14.0625cm X 7.4cm X 2 = 653.9cc Convert millimetres to centimetres in the calculation to get the result in cubic centimetres
