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I kinda put that message out as a teaser to see if anyone might be interested. This is mostly an automotive forum, but it does get good gas mileage.
It is an early 90's Huffy brand BMX style bike. The engine is from a Hoffco brush-cutter. The engine is an 85cc two-stroke, 3.5 hp @4600 rpm,Tecumseh with points/magneto ignition and the pumper style carb mounted on the opposite side of the crankcase and in-line with the cylinder bore centerline. This makes it fit in the small frame opening fairly easily. A cut-off 3/4'" shaft from a 5hp Briggs and Stratton with a 3/4-10 nut welded to it is utilized so it can thread onto the Tecumseh crankshaft. This in turn allowed the use of a standard Comet torque-converter. The crank set and bearings were removed from the bottom bracket and replaced with a "sealed bearing" kit with an inside diameter of 19mm. A 3/4'" keyed shaft couples the driven pulley of the torque converter on the left side of the bike (acting as a jack-shaft) to the right side of the bike where a #41, 10 tooth sprocket is attached. A #41 chain drives the freewheel on the rear wheel. A 48 tooth sprocket was welded to the back side of the original 14? tooth freewheel sprocket. It could also be bolted due to the bolt pattern in the sprocket used. The gear reduction on the torque converter is infinately vairiable from apx. 3:1 to 1:1, maybe a slight overdrive. It works really well and is rugged and simple and coasts like a normal bicycle. I have taken jaunts of 30 miles on one 48 ounce tank.
The engine is solid mounted to the frame with 1/8 " plate welded to the thin wall tubing. Pictures are worth a thousand words so I'll post a link later.
Steve Gibson
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