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Motorcycle Repair/1994 Yamaha RT 100


Hello Sir,
I have recently bought a '94 RT 100 and I'm having some concerns about the oil tank. However I'm not a big, fancy mechanic or know anything about a bike to save my life.
I understand that this is a 2 stroke engine and was wandering, can you take the oil tank out and mix your own fuel? Know I have heard some things about this particular set up that it could render unreliable or mess up your engine.
Would it be better to take off or should I leave as is? And if I were to leave it, do I put regular unleaded 87 gas in the main tank?

Hi Christian,

The RT100 is a very good bike when taken care of.
Yamaha makes a very reliable oil injection pump
and it is very simple.

The tank is filled with a good quality two-stroke oil
and the pump gives the engine the correct amount
of oil for the engine speed.
This results in less smoke and the engine runs cleaner.

If you are worried about the oil flow remove the oil pump
cover and you will see a small screw with a sealing washer
on the side of the oil pump.

Remove this screw and the oil should run out of the screw hole.
Let it drain a bit on an old rag and watch for any air bubbles.
If the oil is flowing steady then just replace the screw and washer.

There is also a vent tube on the tank you have to keep clear
but this is a very reliable oil system.

Some people add a little two-stroke oil to their fuel just
so they won't worry about it. Add an ounce of oil to the fuel
if you feel concerned.

Four stroke bikes depend on their oil pump all the time
and the Yamaha pump is just as good quality on the two stroke.

The only problem is when people forget to fill the oil tank.
I worked for Yamaha for many years and never saw a bad oil
injection pump.

When you mix oil and fuel the ratio is always the same
so the oil is excessive at idle but not with the oil pump
as it adjusts the flow automatically.
This prevents carbon build up in the engine and the exhaust pipe
which hurts performance.

Just bleed the pump as I mentioned for peace of mind
and then add 2 stroke oil to the oil tank and regular or premium gas
to the tank. Premium fuel may run a bit cooler.

Enjoy your bike!

Wayne S

Motorcycle Repair

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Wayne S.


Licensed Motorcycle Mechanic, Knowledge of motorcycles from 1960 up, Japanese, British and most other brand motorcycle repairs.


Worked for Yamaha, Honda, Suzuki, Kawasaki British: Triumph, Norton, BSA Other: Most Scooters and Mo-Peds

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