Originally posted by Scott Fisher
How can there be a performance advantage. They are the SAME. Only the tuning and maybe a little luck in terms of parts fitting will make one different from the other. The only thing I can thing of is if my memory serves me correctly, the NSR has a 9 fin head and the JP has an 11 fin head. This will make a difference to those that use stock cylinder heads.
Ummm, stock JP FX has the same port timings on the sleeve and the crankshaft as an NSR?
But about the heatsink thingy, I never had a problem using 9 fin on my RRL5. Even on a hot 30 odd degree Celsius tropical climate.