The Yamaha RXS is a Posilube system ie: a small pump supplies the engine with the correct ratio, Use semi synthetic, or full synthentic 2 stroke oil for clean virtually smokeless exhaust.
24 to 1
it should be 24:1 if your using yamalube 2 stroke oil
Premix (mix oil and petrol at a certain ratio) Contact you local Yamaha dealer for the best mix.
Yamaha recommeded 20/1
No, Yamaha's TTR lineup is all 4 stroke motorcycles.
It should be posted on the outside of the engine. Not shure what yours is, but mine is 100:1 after the break in period. (10 hrs) If before that it's 50:1
25 to 1
I have a 1983 IT175 Yamaha and the fuel mix is recommended by Yamaha at 28 to 32: 1 I use 30:1 ratio. Hope this helps
50:1 ratio
40;1
If it the Yamaha import it 100:1 and if late model Mercury built it s 50:1
I would run a mix of 32:1 with 89 octane fuel.