I have 2 old school friction drive motor bike engines. These were made in the 70’s to convert a bicycle into a motorized bike. Both engines have great compression and good spark and both have the handle bar mounted throttle control. Both engage with a suicide type lever. The first one is a 1972 K&S Bike Machine. The plastic gas tank and fuel lines have seen better days but it’s nearly 50 years old. From what I found out this K & S Bike Machine uses the same parts as a PB400 or PB300 backpack leaf-blower made in the 70’s. Engine model # T15M-2C-08. The other is a 1979 Sears Free Spirit. This was put out by Sears for only 2 years 1979 & 1980. It will need a gas cap and fuel lines. Engine model # 298.488511 These were kinda like the Whizzer motorcycle of the 1970’s $325 for the pair