The PWK dosent allow for enough air at idle / slide closed so stalling can be an issue on the big engines.  You have to run a slightly longer than stock slide stop screw (metal screw from keihin will be in all the way with no lock nut).  On the up side, they are crisp with the right slide - im running a top trimmed #6 on a 41mm, and offer great performance mid to top. Bumping up my slide a c*n! hair should solve it, ive just learned to deal with it for now.