# Chopper Style Motorized Schwinn



## Thurman (Apr 2, 2018)

I latest motorbike project is a chopper style for my friend Dave. He's a Harley rider and Insisted on spring fork, sissy bar, ape hangers and fishtail exhaust. I was able to incorporate most of what he wanted. We used a 1962 Schwinn bike I gave him a few decades ago and fitted it with a 5hp Briggs motor. Each new bike I build, I like to try new stuff. I told him you couldn't use a bicycle seat with a sissy bar and I wasn't going to use a banana, so I formed a steel platform with a wooden base and rebond foam cushion. We cut up one of his old Harley leather jackets and had a guy I know upholster it.


















Then I fabricated a kickstart mechanism. It took some engineering and trial and error but came out real nice and works great.

















Then I wanted to make a tank shifter, so I fabbed up some parts and linked it to the magneto and used it for variable timing.

















I also used a 3D Motorsports clutch and mounted it right into the seat down tube.











I adapted a larger flywheel onto it for a smoother running engine and nicer idle. It also helped with kickstarting and taking off. Then I trimmed a Harley air filter cover to fit the flywheel.






I wanted a primary belt cover to resemble an old knuckle or panhead so I made a wooden buck and Dave knew someone who could vacuum form chrome plastic over it. It's about 2/3 scale and looks killer.






















Still needs a fishtail, but we're not done.


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## rusty.kirkpatrick (Apr 2, 2018)

Damn, you definitely know your stuff. Cool project.


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## Thurman (Apr 2, 2018)

Thanks Rusty, I've been building motorbikes way before the chinese kits. The air filter is a Tecumseh lawnmower filter between two brass automotive soft plugs and the front drum brake is from an old Japanese motocrosser.


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## 49autocycledeluxe (Apr 4, 2018)

very cool.


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## Thurman (Apr 4, 2018)

49autocycledeluxe said:


> very cool.



Thanks 49, I had a lot of fun with this one and there's a lot of details I left out. . Anyone interested in the complete build thread can view it here.


https://motorbicycling.com/threads/daves-1962-schwinn-briggs-bike.62250/


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## Chiptosser (Apr 4, 2018)

Thurman said:


> Thanks 49, I had a lot of fun with this one and there's a lot of details I left out. . Anyone interested in the complete build thread can view it here.
> 
> 
> https://motorbicycling.com/threads/daves-1962-schwinn-briggs-bike.62250/



Very nice work!!!            I want to know more about that clutch set-up!


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## Thurman (Apr 4, 2018)

Chiptosser said:


> Very nice work!!!            I want to know more about that clutch set-up!



Thanks Chiptosser. The clutch is supplied by 3D Motorsports   https://3dmotorsport.net/collections/manual-clutches  .   It is the first successful manual clutch that us do it yourselfers can use on our custom builds using motors with a 3/4'' keyed  PTO shaft. Designed for go karts and adopted by motorbike builders, it works just like a motorcycle clutch with a handlebar lever. Very easy pull activated by steel balls on ramps to disengage. Very well made and reasonably priced. Comes in kit form or separately with all parts readily available. They come with a sprocket but I adapted a pulley to this one. I prefer belts on a cruiser for lack of maintenance and noise. My grandson laser cut the housing from 5'' box tubing with 3/16'' wall thickness. Mounting it into the frame gave it a neat and clean factory look while allowing for easy belt alignment. It's supported on both ends with substantial bearings that are in a flange and easily adjusted. I've built 2 other bikes using this clutch with excellent results. They are both mounted on the motor instead of a jack shaft.


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## bricycle (Apr 5, 2018)

Truly WoW!


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## StoneWoods (Apr 6, 2018)

Kickstart is killer! I think I might steal your idea!


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## Thurman (Apr 6, 2018)

StoneWoods said:


> Kickstart is killer! I think I might steal your idea!



That would be cool. I based mine on a Briggs 5hp flathead. Most industrial engines of similar size have the 4 bolt pattern with 5/16'' threaded holes or blanks that could be tapped easily. So I can give you those dimensions or supply you with a base plate. The most involved part was the freewheel I had to adapt to the 3/4'' keyed motor shaft. I can help you figure it out. What motor are you planning to use? Photos?


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## StoneWoods (Apr 6, 2018)

Thurman said:


> That would be cool. I based mine on a Briggs 5hp flathead. Most industrial engines of similar size have the 4 bolt pattern with 5/16'' threaded holes or blanks that could be tapped easily. So I can give you those dimensions or supply you with a base plate. The most involved part was the freewheel I had to adapt to the 3/4'' keyed motor shaft. I can help you figure it out. What motor are you planning to use? Photos?



Check out the thread https://thecabe.com/forum/threads/3hp-motorized-bike.100205/ . My plan is to remove the pull start assembly and shrouding and mount it on the outer side of the flywheel. It’s a predator 79cc 3hp from harbor freight.


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## Thurman (Apr 6, 2018)

StoneWoods said:


> Check out the thread https://thecabe.com/forum/threads/3hp-motorized-bike.100205/ . My plan is to remove the pull start assembly and shrouding and mount it on the outer side of the flywheel. It’s a predator 79cc 3hp from harbor freight.



Oh Yeah, I was looking at your thread. Nice project. I would lik to have it on the right side also but was just too easy the way I did it because of all the mounting holes for a base plate. You can mount your pivot shaft at the rear of the engine using the 2 mounting bolts. Also a freewheel with the flywheel retaining nut built into it would just leave the segment gear to deal with. You may want to check out this thread by a friend of mine who mounted a kicker on the right side.


https://motorbicycling.com/threads/briggs-kick-start-motorbike.25549/


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## StoneWoods (Apr 7, 2018)

Wow! Thanks @Thurman ! That’s killer. How did you make the kick gear on yours? The part that the freewheel meshes with.


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## Thurman (Apr 7, 2018)

StoneWoods said:


> Wow! Thanks @Thurman ! That’s killer. How did you make the kick gear on yours? The part that the freewheel meshes with.



Thanks StoneWoods. I made the first one by welding a bunch if 5/8'' dowels into a curved piece of metal. Then I made a blueprint and my grandson plotted it on his CAD program. Then he uploaded it onto a laser cutter he works with and cut it out real nice. It meshed a little tight so we backed off on the radius until it worked real smooth. It took about 6 tries to perfect. Nothing easy, just kept plugging away until I had a complete mechanism. I'm going to have him make a couple more so I can upgrade my older builds that are currently only pedal start. The big advantage of the kickstarter is that I don't have to incorporate a compression release.


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