New / Old YZ Project

Hey guys, I just restarted a project I’ve had for awhile and I need a little help. To make a long story short, I picked up a YZ80 and I was told it was a 1985 but after running into some issues I now think the frame is an 1986 or 1987 (10th digit in the vin is a G) and the motor is ether an older or newer model.

I ordered a replacement water pump impeller (part number # 22W-12450-00-00) that covers 1983-1992 but it did not fit. The impeller that came out of the bike had a fatter shaft than the unit I ordered.


Is there a way to identify what year the engine is visually? It also looks like the engine had a case replaced at some point because the place were I assumed the vin would go is blank


I’ll add a few photos on the engine