There were some other tricks, I've forgotten much of it. You probably know about the 2nd/3rd gear exchange to improve the ratio differentials. We did something to the centrifugal cam weights to alter the advance curve, but it's a distant memory. And a copper head gasket is recommended, since it's more durable and can be reused many times. There's a fellow on ebay who custom makes them if you send him a pattern: http://cgi.ebay.com/ebaymotors/YAMAHA-6 ... enameZWDVW
--Randall
250 Road Race Motor
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