I actually tried two different solution: I bought the bike with a Webber progressive 32/36 carb already fitted, which ran rough. I rebuilt that carb, which improved performance, but still not right. I then bought a progressive 32/32 Webber, which was a match for the 1000cc engine, but again, was weak at lower RPM and didn't like the cold. Pistol Pete uses the Randakk rebuild kit and it seems to have done the trick. Kind of wish I had bit the bullet originally and gone this way, rather than a year's messing around.