Ok, heres a good link regarding Harley's and firing order: http://auto.howstuffworks.com/question325.htm

315*, then 405*, lather/rinse/repeat...

All makes sense now.

Sounds like staggering the lengths of pipe and putting a cross-over or Y-pipe at the right length could really help things out. (since their not really "firing" at the same time)...

Although I gotta admit, my buddy's Fatboy with twin chrome pipes is pretty trick lookin'.

 

the specific advice id give your friend on his warrior is to use Yamaha's "racing" exhaust system.

athough if hes going from a stock exhaust (the HUGE tube on the side) to ANY good exhaust, hes going to have this problem.

why?


because his bike (even though its EFI) is set to run very lean with the poor flowing stock exhaust, for emissions... once you put a nice free flowing exhaust on it, it doesnt get enough fuel, and it has a slight bog down low.

yamaha has a whole trick setup that you can do in "stages".. or you can go all out and just buy it all at once... thoes bikes can be real monsters...

 

He's using the power commander to tune the fuel map, and that has made it more liveable. From what some of the experts have said, it sounds like there's really no solution but to replace the exhaust.