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Old 12-13-2014 | 08:52 AM
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Scota4570
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av8tor1977, check your PM's

Regarding the Craftsman. Since I got a bunch of the them I decided to mess with the ports. Before I started the exhaust duration was about 125. The transfer ports were 90. I crudely opened up the exhaust to 160 and raised the transfers to 140. It spins up a 16x8 to over 8K. The 18x10 goes no faster. The small prop is a lot faster. The thing is is doesn't idle well and is tough to keep running smoothly.

The tops of original transfer ports are at 90" to the side of the jug. That seems like it would not flow well. Even so, I put a fresh jug on it with a matching low time piston, it runs smooth again.
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