I cant find a model specific manual for my 1990 yfm 250 moto-4 anywhere. Needing stator specifications among other maintenance info.

 

Don't know if Tradebit has yours or not..https://www.911manual.com/yamaha-atv-repair-manuals/

 

Forget manual readings,if it is charging between 13v and 14.5v at the battery when running, the alternator is OK. If not, do the alternator windings short to earth? Do all three (if it is three phase) have roughly the same resistance? If it won't run due to lack of spark at the plug, does the exciter (if fitted) produce a decent AC voltage when engine is spun on starter, and does the trigger coil produce an AC voltage when spinning engine, (can be as low as 1v)?