Polini 130 setup (agin)

Built engine as follows

130 polini case transfers matched, race crank, Simonini d & f. with 16
degrees igition timing. Standard gearing set up.

25PHBL running 92 main & D22 needle, 262 atomiser ( set on 2nd clip).

Its only reachin 80-85km with poor acceleration.

Will the exhaust be the problem or can you suggest adjustments to the
carburretor. Plug colour is mid brown with any main jet used between 90-95.

DEmented

Does it go well in 1st 2nd and 3rd but not in 4th? And gearing is what std? 90? 125? What size are the primary’s? Can you borrow a different exhaust to try, cos like the malossi 135 post it sounds like the wrong choice of exhaust or wrong gearing. These types of pipe love revs, and then more, but only give useable power across a VERY narrow band, and high up the revs. You will also get very high wear rates, expect to replace rings at very short intervals, like 500-2500 miles. If your running std crank and flywheel, also expect problems. BE AWARE!