Overheated Axle

[Iron Horse]

Greetings everyone! I decided to join the motorized bicycles anonamous after seeing one at a local bike show. I took one older Murray Monterray coaster, added one newer chinese engine, stirred in two fancy tires, and covered with copper Chrysler paint trimmed with black, and rode it well. The problem is that if I ride this thing at high speed for a fair amount of time, the rear hub gets pretty warm. Not so much that you can't touch it, just hotter than I think it should be. I overhauled it using the slimiest grease I could afford (aviation grease at 40 a gallon), which I have used on all my other bikes with no problems whatsoever. Any suggestions?

 

[cobrafreak]

Sounds like you have excess drag due to either the bearings being adjusted a tad too tight or your coaster brake is dragging. If you lift up the rear of the bike and spin the wheel with the motor chain removed the wheel should spin for a long time. If it doesn't you have to fix it or you will either have a bearing or brake failure.

 

[Iron Horse]

I checked bearing tolerance before the wheel was mounted, and just before putting the chains on. Both times the wheel spun freely, and for a longer time than some of my other "conventional" coaster rebuilds. This is one of those brakes with the spring to return the brake shoes to a neutral position after braking. The only thing I can figure, is that there is a miniscule amount of drag present and while not enough to affect the bike AS a bike, it is enough to affect the bike as a moped. Sounds plausable, however I never was an engineer. Thanks though!