Neat bike, they are an interesting engine, very distintive sound,I think it has something to do with intake roar, the ones I seen were running 44mm carb. Apparently exspensive to repair and run, meet a bloke over there and helped him change sump gasket (cover under engine 2' X4'), shame we found part of a gear with a third of the selector groove attached, he elected to run it as it was shifting OK but the engine let go towards the end of the day. They are fast though.