Oil/fuel mix

[trikidiki]

I have an old air cooled yamaha I believe to be a mid seventies model 5BS can anyone tell me the correct oil/fuel mixture and what type of spark plug I should be using, I tried a 25:1 mix and it ran for a while until the plug fouled up.
Thanks,
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[robert graham]

The 50:1 gas/oil ratio is fairly standard and accepted....I'm not sure about the spark plug number, but it may be on a little metal plate on the motor bracket.

[trikidiki]

Fuel oil ratio

Thanks for your help.

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