(25-09-2011, 12:31 AM)Manx Mist Wrote: I heard a few years ago that there is equipment available to accurately measure bore size through a plug hole.

Stroke can obviously be measured easily this way anyway, so if this technology does exist it will save a mass of time and money.

Has anyone got any info on this? I know this doesnt address things like camshaft lift and other internal specs for supersport regs but at least it could be used for the basic capacity checks.

And thinking about it, if it doesnt already exist, it wouldnt be that hard to make such a device to accurately measure bore size, i've got a design in my head already.

Just asked my mate Google.

Our American friends call this a "Cubic Inch Tester." (Google it) From what I have read it's widely used on their V8 car racing.

I think it works like a compression tester. It measures the volume of air in the cylinder as the engine is turned over.

I found a guy on a forum who describes it's use:

It is basically a graduated cylinder with an indicator inside that will measure the amount of air pumped out of the cylinder through the spark plug hole when the engine is cranked over with the valvetrain closed. The temperature of the engine is measured prior to the volumetric reading as gases are greatly affected by temperature. The volumetric reading is then compared to the corresponding volume on the chart at that temperature to give the actual volume of the measured cylinder. When multiplied by the number of cylinders in the engine, it gives the total displacement of the engine. This is an effective way of measuring the engine's displacement without tearing it down.
The reason this is done is for making sure an engine is at or below the maximum displacement for certain racing classes such as stock car racing and drag racing. It is NOT done to determine the fitness of said engine.

If the volume of the cylinders from each manufacture was known this tool could be used for comparison.

YES. This would only help in the displacement rule. (just incase)