alvin l nunley
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what pipes do you have? I've made quite a few over the years.AL, since I have some of your pipes, what length would you suggest for stock appearing Yamaha/gas and Stock appearing Reed/alky. Clutch slip. Thank You
Clutch slip on the KT is about 10,300. That number is pretty close for almost any pipe. There are a couple of exceptions. Of course the direct drive pipe and the Horstman HPV.
Read/alky would depend on the exhaust port opening in degrees. The KT exhaust opens at about 92° ATDC, so if you're exhaust port is higher than that, set it shorter, and lower, set it
longer. A change of one quarter inch is significant.
The reed valve clutch stalls a little lower, the rotary valve a little higher. I've never tested any of those engines with alky, and of course any change in the port timing would change all this information. As a general rule of thumb, a higher exhaust port would tend to raise the RPM where the engine reaches peak horsepower, and in that case, you would want to try a shorter header.
Comments compliments criticisms and suggestions always welcome.