batman
Serious Thumper
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SuzukiSavage.com Rocks!
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osceola new york
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Ruttly said," porting singles is easy" and he's right. but I think it may be better to say porting singles is easier. Lancer said attention is needed on the inside curve of the exhaust channel which is also true,(The gases wanting to hug the inside of the curve) but going craze grinding ,(removing to much material) can also ruin the head killing any chance of gaining hp and maybe even ending up with less. A well designed exhaust channel,(which we don't have) starts just behind the exhaust valve ,where the opening should be 85%-88% of the diameter of the valve and be only 6% larger at the exhaust header, as our exhaust passes the "shelf "the area just in front of the header pipe it becomes much larger and is why our motors have such low power . The pressure waves and gases ,when the valves first open can leave with speed as high as mach-1(the speed of sound) but as the exhaust stroke continues this drops and pressure increases ,this is where the size and shape of the channel becomes most important. A smaller channel, without a tight radius, may flow better because there is less drop in speed and less pressure (read back pressure)formed , and the reason to grind carefully. the size and contour of the channel represents 97% of it's worth ,polishing accounts for the other 3% so may not be worth the effort ,and may also remove to much material. this is one place where less(grinding) may be more(hp) .
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