4 Stroke Bicycle Engines & Kits4 stroke motorized bicycle engine kits are great if you want reliability or do not want to mix your oil and gas. Learn from each other how to get the most out of your 4 stroke bicycle engine
There's a guy on the home page of SickBikeParts.com that has one on his two stroke kit. I guess he says it works well. I've seen them on ebay and even some local bike shops in the Twin Cities metro area have them but there not cheap.