Wont Rev Past 4000 -4500

Dec 27, 2005
Me and My Dad often ride two up but when we want to get her really goin it just doesnt seem to go past the 4000-4500rpm mark just basically stops this is in all gears and duin around 7-80mph in top and wont go anyfurther

i am running a points ignition, standard 932 amal carbs, 220 size mains, reverse cone mufflers and it is a 750 combat motor.

what will i have to change to get this thing into its redline??
I had the same issue when i changed mufflers a couple of years back, turns out my new ones were too restrictive. Ended up buying some cheapies which were way noisier but now it can breathe.