this is directly from Yamaha i work at a dealership 5w oil is recommended 329cc or 90mm oil height
fork oil amounts for a Yamaha GT 80 are 108 to 116cc's per fork tube. you should use 10w motorcycle fork oil. this is good for all years from 1974 to 1980.
135mm (80-150)
0.9 quarts or 1 liter.
15 to 16 U.S. oz.
32:1
Type your answer here... DS 80 uses 80ml of SAE 10 per fork leg.
Faulty sending unit.
About 80% of it's oil!
there isn't a level 80, it only goes to level 30.
Level 80 is the highest level you can reach before you prestige.
about level 80+
They do need fork oil. Check the seals, might have to be replaced. If you have a air valve, they do have air suspension. Just can't remember the ' 80 model.