Well now that all the new parts are on this 1988 Yamaha 80 moto4 and I crank it to start it has everthing but compression. This rig sat for two years, does the ring pack seize and valves seats corrode over time? I did shoot penetrating oil in the cyl and crank it to spread it around. one other question does the unit have a decompression valve? Any help to get me to the next step. do I have to pull the cyl head off?

 

yes i have a moto-4 80 and i just use JY455Y00XF0021220

 

They need really good compression or they won't start unless you tow them. Manual says min 140 ish lbs. 175 is normal compression.
Link to manual here
6789438-Yamaha_Badger_80_Service_Manual_Repair_1985-1988_Yfm80.pdf

Whatever you do don't try to run it with the left side cover off over the flywheel or you will be pulling the tranny apart with me

 

Oh man, that's a lot of compression. I'm sure the free one I just picked doesn't have that high of compression. It must be tired and in need of a rebuild.