Update on my rewound UE motor.
It was running great, lots of power and about twice the speed. So i wanted to push it all out up a steep long hill. When i got to the top of the hill it seemed to loose about half of its power, i took it easy and rode it home to take it apart to see what happened. To my amazment 2 of the 4 brushes melted the solder and the wires came off. Wow thats about 460 degrees, much hotter then i would ever had thought. I'll try to buy some high temp solder and put a blower on the motor to cool it and see if that helps.
I would like to get a bosch gpa 750 motor with a built in fan and rewind it. If someone has a rewindable motor and wants to sell it please write me at paul_scooter [at] yahoo.com
I was riding my Charly a few weeks ago and ran over a nail. I didn't notice until it was too late and the increase in rolling resistance burnt out the motor. I just put on no flat tires so that will never happen again.
I wanted to rewind the Bosch motor but never did anything like that so i decided to experiment on an old Urban Express motor i had. I wanted to have a before and after comparison for the UE motor rewinding.
I replaced the Charly Bosch motor with the UE motor, to my surprise it fit on like it was made for it. My top speed was only12 MPH, with fair torque, so it was a little slower on top end and climbing hills then the original Bosch motor.
I removed the UE motor and unwound it paying attention to the winding pattern and the number of turns.
I think the wire size in the UE motor was 20 gauge using 12 turns per winding. It looked like it had room for many more turn or a much larger gauge wire . I rewound it with 16 gauge using 6 turns because that was all that i was able to fit in the coils. Knowing that the RPM would approx double i used high strength epoxy to fill the small coil gabs and hold them in at high RPM.
When i tried out the motor i was very surprised at the speed and power of the motor. The flat road max speed was now 24 MPH and the hill climbing ability was noticeably better.
I have one more UE motor that someone gave me and i think i will rewind that now that i have a tiny bit of experience at it. I can do a much better job and practice once more before i rewind my Bosch motor. It was a lot of fun and a great learning experience. I was very surprised at the great outcome.