1980 750F Rejet

[Curt750F]

I have an '80 Supersport, and I recently put on a Mac 4 to 1 exhaust system, sounds great!  It revs a little higher and gets up and goes just a little quicker.  When I get up around 8500 to 9000 RPM I get some sputtering and hesitation, same goes for when I'm up around 100mph.  My question is do I need a rejet or is there something else wrong here?

[woodsrider250-2]

Running airbox/paper filter?  Make sure air cleaner is fresh.

Increasing PRIMARY main jet in carbs from 68-75 will help.  Most have the problem sooner in the range than that.

[dylansdad022102]

your float bowls might be draining due to the higher demand for gas at those speeds. might wantt to try adjusting the floats a little and upping your primary jet 1 size

[dylansdad022102]

your float bowls might be draining due to the higher demand for gas at those speeds. might wantt to try adjusting the floats a little and upping your primary jet 1 size