Hi, presume you mean throttle bodies, no carbs.

I understand the 150 sigma is well know to run poorly on occasions, but yours must be something else, where are you based

I am in East Sussex, small town called Uckfield.

I have the same problem with my Sigma 125 engine. Just learned to manage it. I'd be interested in how you get on.

Hi, Same problem with a 2012 140hp Supersport. I was advised by someone who'd built a Blackbird powered 7 which had a ridiculously light throttle spring to increase the spring tension. I added another coil spring to the top of the throttle pedal and bingo, it reduced the kangarooing quite a bit. It's still there which you have to manage but it's much improved.