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Dirt Bike Discussions By Brand
Yamaha MX & Off-Road Dirt Bikes
250f mod options
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[QUOTE="Rich Rohrich, post: 140977, member: 16241"] I haven't gotten my 250F cylinder head yet so I haven't had the chance to do in-depth testing. If it's anything like the 400 & 426 heads I'd suggest you look elsewhere for horsepower increases. The heads can be cleaned up and made a bit better, but there is nothing major hiding in the stock 400 design. It's VERY GOOD. Chances are the 250F head is even BETTER out of the crate. At 13500 rpm you can't screw up the cylinder head and still make good broad range power like this engine does. Blueprinting the cylinder head and deck heights will certainly pay some dividends but tend to be a poor value in terms of HP/dollar. I realize this won't stop "tuners" from charging outrageous prices for porting. [b][i]caveat imperative of cavere[/i][/b] High end fuels (oxygenated or high energy blends) will meet the power requirements you outlined and still be AMA legal, but it's still not cheap and it takes some tuning work to realize it's advantages. No free lunch when the engine starts out this good :) The camshaft is the area where there is the most to gain, but I haven't seen anything (SO FAR) that meets your requirements. [/QUOTE]
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Dirt Bike Discussions By Brand
Yamaha MX & Off-Road Dirt Bikes
250f mod options
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