OK so I'm new to the board and just got an old '84 FL250. I had the Engine bored 1 size over but the guy I bought it from said he had bored it once before....anyways I have a 2 piece performance exhaust that came with it but it kept back firing and blowing the 2 pipes apart so I just went back to the original pipe... also I have put the mikuni 34mm flatslide TM carb and the old K&N open filter. spark plug is new. It is bogging down on the high end. I started with a 270 main jet and have worked down to a 220... I has gotten a little better but not much although with the 220 main jet the plug is the nice lightish brown you want (I think that's what you want)... does anybody have any other insight as to why it is faulting up high. Also It has a temporary gravity feed gas tank but im switching back to the original and just got a brand dew mikuni pump. where do I hook up the middle nipple to to drive the pump? Thanks!

Jeff

also one of the times the pipe blew apart the exhaust gasket/seal blew off and I never saw it again, currently running it w/out one, would this make a large difference in performance?

I had a K&N on my 350 but was strongly advised to get a 'real' filter that actually filters the dirt out.

Upon inspection of the K&N it was very dirty on the inside & you could see straight through it. :-/


Perhaps the bowl in the carby is over filling or the other side, not filling fast enough to keep up at WOT (Wide Open Throttle)??

My 350 was doing a similar thing, but, it was overfilling & flooding.

Sorry mate, that's all I can think of.

Maybe some of the others can offer more or better advice?

Good luck.