I got an idea from watching multi-speed RC cars shifting at certain RPMs into a higher gear. At a race last year I mentioned to Briggsbiker, Anthony, that it would be cool to build one for my race bike. He said he had one on an old Rupp mini-bike and that it worked okay. I researched it online and discovered Maxtorque was producing the proper components and they were being offer by someone for restorations. Anyway, I set out to duplicate their system. I started by buying the only part that was different than any other minibike, the double sprocket clutch sold by BMI. Somewhere along the way I chose to enclose it all into a removable case as it was way too bulky to have the clutch on the motor and the jackshaft on the frame. Also I wanted to include a pedal start mechanism integrated into the same case.
I started with the case, forming pieces of 1/8'' flat strap into rounded end caps and flat sides to weld onto them. Added rings to hold bearings and mounting tabs.![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5860_zpsad89794d.jpg&hash=1b8b27a868907c6af9844d7b55df0577)
Got all that welded together.
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5869_zpsa50a8320.jpg&hash=884eb0f824eec9228782636eee1cbe53)
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5870_zps9770ac56.jpg&hash=265dc1fdccb6b395ce081153c1c9b5ba)
Then I had to make a similar part for it all to slip into.
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5891_zps40c5ea29.jpg&hash=80ac5544439a8927bde489b162079268)
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5890_zpsb9c06b31.jpg&hash=e7330a90fd09bc773111d3a9c8fea996)
I started with the case, forming pieces of 1/8'' flat strap into rounded end caps and flat sides to weld onto them. Added rings to hold bearings and mounting tabs.
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5860_zpsad89794d.jpg&hash=1b8b27a868907c6af9844d7b55df0577)
Got all that welded together.
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5869_zpsa50a8320.jpg&hash=884eb0f824eec9228782636eee1cbe53)
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5870_zps9770ac56.jpg&hash=265dc1fdccb6b395ce081153c1c9b5ba)
Then I had to make a similar part for it all to slip into.
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5891_zps40c5ea29.jpg&hash=80ac5544439a8927bde489b162079268)
![](/proxy.php?image=http%3A%2F%2Fi1047.photobucket.com%2Falbums%2Fb478%2Fmsrfan%2F2%2520%2520SPEED%2FDSCN5890_zpsb9c06b31.jpg&hash=e7330a90fd09bc773111d3a9c8fea996)