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.
The 1974 Yamaha TY 80 typically requires fork oil with a viscosity of around 10W. The recommended volume for each fork leg is approximately 120-130 ml. It's essential to use a high-quality fork oil to ensure proper damping and performance. Always consult your owner's manual for the most accurate specifications.
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.
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.