I'm still breaking in, and running a stubby port matching intake with a twin (air/fuel) adjust sha clone that is a little lean with a 63 jet. no filter, rain sock material instead. port matched, intake skirt, mild exhaust pipe matching and stinger cut down. top so far with this set up is 55 kph/34 mph with 44t and I'm about 210 lbs. this is a zoom crank case and Cheez everything else. running amzoil saber 50:1 still, next tank will probably 75:1 and maybe play with richer ratios after. 100:1 would be nice. will try larger jets next and different exhaust set up, down the road a sbp hd jackshaft set up would be nice. for the near future I have a 56t waiting, I want to cruise at 40 kph and be able to hit 50 with the 56t though. also, no chain tensioner used. so I'll have to see what I can squeeze out of this little doll.