I've got a PVL on the Villiers - works so much better on throttle response without that big heavy flywheel. The only problem I've found, and it seems to be fairly common, is that the spark can hardly be seen turning the engine over by hand. I thought I had no spark last week after not having run the bike for ages. After cleaning all contacts and earths in sight, I just gave it a good kick and away it went - yet the slow turnover is just a flicker.