A bike engine in a car gets whatever it measures to the inch. A 60 inch motor that measures 60.900 isn't 61 until it measures 61 or above.
A bike has the overbore allowance for the same dumb reason the cars seem to do without.
So the same motor in a bike might be OK but too big for a car.
This concept has confused me, not hard to do, and I have wondered about it. I'm using a 750 cc Suzuki with a bore & Stroke of 2.834 & 1.811 in my lakester. Using the SCTA formula: bore x bore x .7854 x stroke x number of cylinders the motor is 45.70 cu. in. and 0.7488 liters.
The rule book says J Class is 31 thru 45 cid [ Approx. Liter Equiv. of (0.51 to 0.75)]. I Class is 46 thru 61 cid. So I'm over 45, but under 46, but it says "thru 45 cid", so I'm thinking that means up to 45.999999, so I'm OK. Am I right
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One other thing when they are measuring (with tools, not air or oil), what are they measuring to, tenths, hundreds, or thousands of an inch? If I measure the above to hundreds then the motor is 45.54 cid.
Looks like no overbore for sure
. Of course all of this is meaningless unless you actually set a record and I have my doubts I'll be doing that. I will have some fun though
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c ya, Sum