info on building a performance exhaust?

80B4 wrote: I will wate untill someone has custom pistons fabricated and then I buy in on a minimum order. I am also looking at pistons from other motorcycles. The hold up is the pin diameter, it's big. I am also looking into having the rods modded to accept smaller more common pins. I've been lucky at finding 750b engines on Craigslist, I have 4 so I can build one and keep one mostly stock If I find an easy way to go big I'll let you know.

YES. if you find any piston buy-ins count me in on a set. Looking forward to the motor you're going to build.

Tyrell Corp wrote: I'd recommend looking at '4 stroke performance tuning' by A Graham Bell

Thanks Tyrell, I just picked that book up used off amazon. There does seem to be a lot of differing opinions on exhaust design. I have seen articles on the web that say the anti reversion inserts don't work, while others claim they do. It seems hard to sift through the bias. From what i have gathered (feel free to chime in here) is the anti reversion inserts don't increase power, in fact in most cases they account for a very small drop in performance when measured on a dyno. However in real world road racing applications they are useful because there are instances where you will be going from WOT, to completely closed throttle rapidly. The engine speed remains high during this period, and the exhaust is at a high pressure still from WOT, however because little charge is being added to the cylinder it has a low pressure, this pulls the exhaust back into the combustion chamber during overlap which causes the engine to be less responsive.

I personally find this all very interesting. and i agree, on my stock motor the exhaust design probably won't have much of an impact, but i would like to design it so that if future engine mods are done the pipe will still be effective, or at least easily modified. looking forward to reading that book.