Hi,
My name is Mark and I'm new to the forum.
I'm restoring a 1984 Tri-Moto 125 for my girlfriend to ride and it originally had the Auto-Lube system. It was pretty messed up, so I have removed and blocked off the pump set-up and will just mix the gas.
My question is does anybody know what the mixture/ratio would be for Yamaha 125. I have tried 40:1 and I cant get the carb idle stop screw to work properly, I have to keep it cranked in almost all the way. I'm thinking the ratio is off, also with the idle stop screw cranked in as far as it is, it won't start when it's cold due to it holding the slide open so far. I'm going to try 32:1 and see how it is or if someone knows what it should be would help, thanks.
Mark D.

 

32:1 is the safe industry standard that everyone seems to follow, but it also depends on the type of oil you use.

If you are using a semi-synthetic pre-mix, you will want to run from 40:1 to 50:1

As for the carburetor, as long as the oil injection hose was blocked completely, I don't see the premix ratio being the cause of your problem

 

Thank's for the input,
Do you think having the wrong ratio would cause the problem of having to have the idle stop screw for the slide turned in so far to get it to idle properly.
Mark D.

 

What you may have is a damaged slide.

I have seen alot of carbs on older models where kids would go and fiddle with that screw without blipping the throttle to keep the crew from notching the slide. Once that happens, the screw has no effect on the idle, because it's only going into the groove and not contacting the slide.

Whether that's it or not, it is not related to your premix ratio.

 

Thank's
The slide is in real good shape and doesn't appear to be the problem, I also checked and blew out all the air passages, etc. in the carb.
I'm going to try running 32:1 and see what happens, if it still gives me problems, I think I will look at the crankshaft seals for leaks. [img]i/expressions/face-icon-small-confused.gif[/img]
Mark D.