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Old 11-11-2011, 01:45 PM
Scootmeister Scootmeister is offline
Motorized Bicycle Elite Member
Join Date: Mar 2011
Location: North Carolina
Posts: 243
Default Build Specifications, "Red Hornet"

Some of you have asked for the specs on the “Red Hornet”, so here goes. I apologize for my verbosity, but there is a lot to spell out because not much of this build is traditional. The platform for this bike is a Murray Westport cantilever frame with mounting plates welded fore and aft to serve as anchors for the brake caliper braces. I also welded a hefty fork stop beneath the head tube to prevent jack-knifing of the front end. A customized Huffy mountain bike fork with 1 inch down tubes was used because standard tapered cruiser forks are not rigid enough to resist flexing when disc brakes are employed, especially with 203mm discs. A vintage Firestone cargo carrier balances out the rear of the frame and provides a mounting point for the oversized vintage Yamaha motorcycle tail light. The front end is topped with a Raleigh alloy gooseneck and extended Wald wide angle handlebars tipped with motorized bicycle grips and twist throttle from BoyGoFast. The full hand brake levers are Tektro Super 8s and the mirrors are billet alloy from JC Whitney. The rear drop outs are fabricated from 3/16” thick steel plates, and the front is a custom built springer, fashioned after original Indian/Harley springer forks. The wheels are custom laced with Shimano disc-ready hubs, SS spokes, and Rhino Lite II double-walled rims. The wheels are wearing Bontrager thorn-proof tubes and Cruzer B whitewalls. My brakes are Avid BB7 calipers mounted to Harley-Style brackets with 203mm (8 inch) rotors. Heavy duty scooter cables drive the calipers. The rear 44-tooth Sick Motorized Bicycle Parts sprocket is bolted to a shimano Super Low drive cog. KMC BMX chains were used for both the primary and secondary drive. The speedometer is a vintage Stewart Warner, it will be replaced shortly with a Chrome Whizzer unit which is much more accurate. I have a vintage bicycle light up front and as mentioned previously, a sizeable vintage Yamaha motorcycle light in the rear for additional safety. Both are connected to a vintage Ever Ready “Space Beam” flashlight battery canister mounted under the gas tank that holds either standard or re-chargeable 6 volt cells. The on/off switch for the lights was the toggle on/off switch for the engine. The ignition now is a simple on/off keyed switch from an Ariens snowblower. The gas tank is a 1.5 liter Chinagirl special held over from the original kit build. The center kickstand was purchased online from one of the many bicycle part warehouses. I’m thinking about replacing it with a much sturdier Whizzer center stand in my parts bin. The seat is a custom built Harley-Style solo springer with a vintage chrome anti-crash bar. The pan was fabricated from a steel banana seat mated to a large vintage steel cruiser pan. The custom hand-stitched leather cover was made from one of my wife’s discarded knee-high boots. The springer seat assembly/frame was fabricated from pieces of a flat-screen television mount and other garage junk. The springs for both the seat and the front end are standard zinc-coated (not chromed) hardware items.

Now for the fun part! The photos show the progression of this build from a 66cc two-stroke Chinagirl, no front brake, no tail light, and a spoke-mounted drive sprocket, to a Grubee Huasheng 4-stroke with Stage III gearbox and other improvements. I rode the Huasheng configuration for 2 years but got tired of watching my wife speed away from me on her 48cc Yamaha Vino (plus, in a tight spot I had to smoke my coaster brake and it still wouldn‘t stop). In desperation, I swapped out the dependable but anemic 48cc Huasheng for a 46cc vintage Homelite XL chainsaw firecracker with fully adjustable Mikuni carb. I fabricated motor mounts from strap hinges and custom built an exhaust pipe from 1” thick-walled steel conduit. I welded a female pipe fitting on the end of the exhaust pipe and a male pipe fitting on the china girl muffler that came with my 66cc engine so I can swap out the quiet china girl for an unrestricted Briggs muffler which allows the engine to breath very freely. With the open Briggs muffler, the engine jumps to 7300 RPMs very fast. The right hand drive on the Homelite is perfect for mating to a custom-built freewheel that sits behind a custom-designed chain cover. The centrifugal clutch sports a 11-tooth sprocket, the freewheel has a 48-tooth sprocket connected to an 11-tooth secondary sprocket. The secondary drives a Shimano 3-speed Nexus hub regulated by a vintage Shimano “Muscle Bike” shifter mounted to the crossbar. The shifter is indexed with very strong springs and stops for sure shifting (almost feels like a Hurst!). The shifting is easily adjusted with the improved cast aluminum belcrank that comes with Nexus hubs. The freewheel rides on a custom-built extra long lower unit shaft finished off with alloy Schwinn OCC peddles (parts bin). All of the brackets, fittings, and extraneous hardware were fabricated from old bicycle parts or from scratch. I attempted to keep the design true to the spirit of a motorized bicycle, with minimal use of motorcycle parts (after all, when it‘s all said and done, this is still a bicycle). The combination of vintage looks and modern upgrades keeps the raw fun factor high while ensuring that the thing will keep up with my wife’s Vino and stop when I need it to (the 8 inch front rotor with fully compress the springer front end on a hard stop).

I hope you enjoyed reading about my project. Building it was a lot of fun, but a ton of work. I would not recommend this type of build unless you have a lot of tools and a lot of time. And although this bike is a blast to ride and draws a crowd wherever I go, it will be my first and last cantilever build. Even though premium cantilever frames are strong, they simply are not rigid enough to handle the weight and torque of motorized operation. Even the heavy duty cantilever frame on my Whizzer flexes on rough pavement or under heavy braking. The rest of my builds will be chopper-type bikes with strong rigid frames (with the exception of the 1.6 HP Robin Suburu Staton kit I installed on my elderly neighbor‘s 3-wheel Sun recently). I picked up a chrome Giant Stiletto and a new in-the-box Schwinn Spoiler. The Stiletto has a high tensile steel frame like motorcycles and came from the factory with a built-in rear mounted jack shaft to aid in power transfer. The Spoiler came from the factory with disc brakes fore and aft, a real triple tree, plus a wonderful springer front end. Both have oversized wheels and tires which makes them perfect candidates for motorizing. Any tips on either of these builds would be appreciated. You can view the build at:

Pictures by scootmeister - Photobucket

Thanks for your interest!
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Old 11-11-2011, 05:45 PM
5-7HEAVEN 5-7HEAVEN is offline
Motorized Bicycle Elite Member
Join Date: Aug 2008
Posts: 1,912
Default Re: Build Specifications, "Red Hornet"

I LIKE your bike!
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Old 11-11-2011, 09:27 PM
madmaze madmaze is offline
Motorized Bicycle Newbie
Join Date: Feb 2010
Location: bean town
Posts: 4
Default Re: Build Specifications, "Red Hornet"

very nice!
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