I know its not a yam. Has anybody ever seen one?

not since the local mx trak closed about 38 years ago!

Shurly you mean CR500.  Single 2T, ,,  68 bhp,,,,    awsome bike, go on u-tube,,       super moto track day rider,,,, 

One scary motorcycle, only hero's apply.

 

Yes beware the red engine. 10 grand for a crankshaft?