Ok...Not a GS Question, But I gotta know!

[Guest]

I have a late '70's Yamaha (there, I said the bad word!) Chappy 50cc bike/scooter/thing that I picked up cheap for my wife to scoot around on.
It is missing the oiltank/injector pump and previous owner was just running mix gas.
What would the approximate oil/fuel ratio probably be ?
I asked at Yamaha board and got 20 - 1 as an answer, which sounds too light but COULD be right.
I've worked on a million Gs's and i love 'em, but I just thought I would throw this out for an educated guess.
Thanks,
Ozarkdrb

[tkent02]

Modern oil you can go less...
Used 32:1 on the KDX250 a while ago, no worries.

[onchiman]

I have a '79 Yamaha QT50 that I run pre-mix in. 50:1 ratio. Runs great.

[Nessism]

Depends on the type of oil to some extent; old school oils run a higher % vs. newer type synthetic oils.

[Planecrazy]

Ok, just to be a wiseguy I'll suggest you split the difference between the 50-to-1 and 32-to-1!

What ratio did the PO use and for how long? That'll probably be as good a guide as any other opinionated info you receive ... maybe better if he did it for a long time without ill effect.

Regards,

[twistedwankel]

I have a late '70's Yamaha (there, I said the bad word!) Chappy 50cc bike...What would the approximate oil/fuel ratio probably be ? I asked at Yamaha board and got 20 - 1 as an answer, which sounds too light but COULD be right.
Ozarkdrb

I'd run 20:1 synthetic "2 cycle" in your "old" motor and if the plugs don't foul and you don't constantly get the ugly blue smoke you/re in business. You can always back it down after the first tank to less oil if need be. Admittedly 32:1 is easy to remember as 1oz oil per quart of gas.

[focus frenzy]

I would like to add that you make sure and use only two stroke oil formulated for a air cooled engine.

air cooled engines typicly run hotter and oil made for a water cooled engine can gum up and the engine sieze.
I have seen it happen on a vintage air cooled RM250 that was running the same gas mix others were using in their water cooled YZ250's tear down after siezure found alot of tar like gunk.

[onchiman]

I run Amsoil Intercepter 2 stroke synthetic at 50:1. No problems in the 1979 Yamahopper! You will find a wealth of information at mopedarmy or this moped site http://www.mopedriders.org/.

[ozarkdrb]

Thanks! Unbelievably usefull!

I KNEW you guys were going to come through as this board has in the past with really solid and useful info!
(Much better than the previously mentioned OTHER board!)
The Previous Owner was a woman who dumped lawnmower oil into the gas until it "Looked right!) You should have seen the plug and carb.... nasty. had to take muffler/pipe off and heat them up and burn all the crap that was built-up in there out, also.
And somehow - It ran. I think that they are obviously pretty tough and simple machines.
Got some new stuff from Bike Bandit today to fix petcock so I should be getting it in shape pretty quickly.
Then I can go back to wrenching old GS!
Thanks again!
Ozarkdrb

[feelergaugephil]

I run Amsoil Intercepter 2 stroke synthetic at 50:1. No problems in the 1979 Yamahopper! You will find a wealth of information at mopedarmy or this moped site http://www.mopedriders.org/.

That's what I use in my 1985 Yamaha RZ 350.

[Dave8338]

40:1 conventional Dino juice or 50:1 synthetic...