mixing 2 stroke oil

Have an old 84 2 stoke that requires 20-1 fuel mix. Bike has a lot of oil
coming from muffler end. Can anyone explain if the recommend mixture set on
the bike applies to any oil we have today, or to the oil the manufacturer
was using back in 1984? Never really did understand the whole mixing and
ratio thing.


Peter

 

you sur eit is 20:1 ? That is kind of high.

Remove NO-SPAM from email address when replying

 

I'd try a synthetic at 30:1 for starters, and see how that goes.

Charlie

 

The gas/oil mixture ratio for a 2-stroke is determined by the oil far
more than by the particular bike. The manufactures say 20:1 because
that is safe using any old can of oil you have laying around. If you
use a 2-stroke oil that advertises itself as "50:1" oil then you will
almost certainly have no trouble with it mixed at 50:1.

If you will used a synthetic 2-stroke oil such as Royal Purple or many
other quality brands, you can can mix it at 50:1 with room to spare,
so to speak. It will also quit smoking (once you have burned out the
residual in the pipe) and it will quit clogging up the exhaust port
and muffler with carbon.

Again I will say it... the proper mixture ratio for a 2-stroke is far
more a function of the quality of the oil than of the design of the
motor.

 

I wasn't aware that people used castor oil in motorcycles. That's the
oil that's used for glow-plug model engines. That fuel also contains
nitromethane, adding to the racy smell, but at least the smaller of
these glow-plug engines lack any piston rings. And they're very easy
to dismantle and ungum.

I had a Suzuki GT-750 years ago, which used a separate oil tank and
a variable stroke pump, controlled by the throttle setting. That bike
would consistently misfire when run on Suzuki two-stroke oil, as was
specified by the users manual. Running nearly any automotive 10w-30
fixed the problem, at less than half the price for the oil. But the
automotive oils did create more exhaust smoke. I had one person insist
that my bike needed new rings, to fix the blue smoke. I just told him
that it was normal for that model, and went about my business.

 

Question answered. I thank everyone for there input.

Peter

 

(Kaybearjr) wrote in

More likely what you were noticing is the difference in carburettor
jetting. If you are pre-mixing, 20:1 displaces more fuel in the air fuel
mixture than 40:1. If the carburettor is jetted for a 20:1 mixture,
changing to 40:1 represent increasing the jet size by about a half size
richer (2.5% richer mixture). If your jetting was pretty good with 20:1,
changing to 40:1 would make it less good, obviously. Stock jetting tends
toward richness anyway, to keep nitwits from burning up their motors.
Check your carburetion if you are changing mixture ratios.