I agree with sleepy it is 73 400. Engine Number shoud be U450000.
Tank looks like a poor copy of a 76 tank. Brake arm may a Wheelsmith or a copy.
Looks like it has been used as a poadock bike judging by the rear tyre wear. The piston will be wornout and the bigend floged.
I saying that most of bike is original and mostly all there. Which is a good start if you are going to do a resto.
Be awere that to get this bike to any were close race to condition you are looking at spending serveral Thouand dollars.
For example Kick starter $200.00, Start shaft, $100.00 plus , etc, etc, etc.
I know because my brother and i have rebuilt at least 10 Maicos of differant years and Models.
Current Project. Resto a Rare 74 1/2 501. Cost $600.00 just to fix the Oridginal frame. Last owner had butchered it and put in a 4 stoke engine . GMC done a good job.
But do not let put any body off. Remember a good well set up Maico is fun to ride and to race one is almost cheating. Not my words.
