So, my engines nearly back together after honing the glazed bores and fitting adjustable cam gears. When i had it together, it blew big puffs of black smoke when the throttle was stabbed. Fuel. Too much. I was going to change the pin location on the throttle pump plungers to the outer hole, so less is pumped in.

I do remember though reading that you should not change that on the single barrel downdraught strombergs, as it's detrimental to the carb's performance. Can't see why if it's too rich right now. Maybe that statement was purely regarding a single carb setup?

Note that my X2 steup uses two single carbs (1 5/32?), not the smaller ones specced on twin intakes. As mentioned in another topic, i'll have it on a gas anlyser as soon as it's running to make sure the main jets are appropriately sized.

Any thoughts? Cheers.

The accelerator pump stroke should not be altered. Running rich has nothing to do with the accelerator pump.

Main jets, power jets, float level & idle mixture setting etc. are the things to check.

I would make sure you do use the smaller (1 3/32) ca