Help with fuel mix Old tohatsu B9B Air cooled

[Ruddles]

Hello folks
Have just aquired a rather nice but old Tohatsu 5, model B9B , serial 23033 air cooled cylinder with water cooled exhaust.
I need info as to the correct ratio of fuel to oil, and also, the correct type of oil.
The engine was porperly prepared and stowed for a loooonnngggg time. basically like new apart from some small minor corrosion.

Many thanks

Rudds

 

[JB]

Re: Help with fuel mix Old tohatsu B9B Air cooled

First of all, I recommend that you use oil for air cooled 2 strokes, chain saw/weed whacker oil.

If the engine has all "frictionless" bearings you can probably get by with 40:1, but we don't know that, so, lacking input from someone who knows that engine I would go with 24:1.

 

[TOHATSU GURU]

Re: Help with fuel mix Old tohatsu B9B Air cooled

You have a model M5A or a M5A2. I suspect its a M5A2 as the M5A was not exported except in tiny numbers. It could be anywhere from a 76 to 77 (A model) or 78 to 83(A2 model) in production year. There really aren't any parts that are available for it due to its age and the small number of them that were produced each year. If its an A2 it should be 50:1....TC-W or better. If its a 5A I have no idea.