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Engine & Transmission / Enlarged exhaust ports
« on: November 07, 2020, 10:00:57 AM »
An engine from a parts bike I bought has a cylinder with enlarged exhaust ports. I estimate they are about 30 - 40% larger than stock and the porting work seems to have been done very carefully. The ports are very smooth and symetrical. After getting the crank redone and replacing the coil, I got the engine running on a test stand set up but can't tell much about the power it may produce. I know from go-kart work I did many years ago, porting can be easily over done. Short of putting it on a bike to check it out, does anyone have a feel how the servi-cycle engine should respond to exhaust porting?