40;1
The fuel mixture for a Yamaha 40 hp 2 stroke outboard engine is 50:1, gas, oil mixture. You should use new gas when you get the engine ready for the season.
dirty fuel injectors
The fuel tank on the 1987 Yamaha Virago 750 holds about 2.3 gallons of gas. This bike is a cruiser with an air cooled four stroke engine.
Why the fuel consumption is less in 4 stroke engine as compared to 2 stroke engine
No, Yamaha's TTR lineup is all 4 stroke motorcycles.
it is oil injected
The correct fuel to oil ratio for a 1996 Yamaha YZ 80 is 60 to 1. The bikes have a single cylinder, 2-stroke engine.
A two stroke engine combines the fuel and oil inside the engine. If your plugs keep fouling, that ratio is off and may be related to the choke or air intake.
Premium gasoline
Sure
Yes !
No 4 stroke motors use 91 octain fuel or better. You only mix oil & gas for 2 stroke motors.