The last of my 2-stroke engines?

[Slacker]

I always use premium in my mix gas. I don't pay much attention to the brand of 2 cycle oil. I always mix it rich. I've been told by a few 2 stroke mechanics that the single biggest killer of these little engines is cylinder wall scoring. Caused primarily by users NOT SHAKING THE CAN before fueling. The fuel/oil mix seperates when it sits. Be sure to shake the can before fueling.

 

[SkyPup]

The reason you need premium 93 octane gasoline for a high revving hard working two stroke is easy, the worst thing that can happen to a two-stroke is detonation under load.....and that is much less likely to happen with hi-test since it ignites slower than regular lower octane.

As far as oil-gas mixture settling out, use only full synthetic ester based two stroke motor oil, it will never settle out since it is solvated into the gasoline stock.

My 125cc two stroke racing go-karts go over 115mph on road racing tracks around the country for a minimum 30 race (with hours of practice) and last 50 hours before rebuilding the upper end and going another 50 hours full throttle full load.

 

[IH3444]

I also use the Amsoil 2-stroke synth. mix for chainsaws. There is a discussion about regular, or high test gas for 2-stroke saw over at Arborist.com website. I use high test also.

 

[MossRoad]

A racing engine and a piece of lawn equipment are two totally different animals. The only time I used high octane fuel in a 2 stroke was when I was drag racing my Yamaha RD400. I ran 100 octane aircraft fuel. I found that it ran very well, but got very hot very fast. However, there was plenty of time between drag races to cool down. I can't see the need to run it in lawn equipment. A properly tweeked carb and a good oil mixed in the gas at slightly more oil than recommended and those little engines will last for a long, long time on regular 87 octane gas. That is what they are designed to run on. A higher octane fuel will cause more heat and that isn't good for them in the long run. My guess is most 2 stoke engine failures are caused by too little oil in the gas and/or too lean of a carb. Eliminate those two problems and they should give years of reliable service.

Just my poinion, of course.

 

[Bird]

OK, you guys have convinced me. I've just been using regular gas in the only 2 stroke machines I have; a Stihl string trimmer and a Mantis tiller. So I pulled out the manuals and they both recommend a minimum of 89 octane. That's the mid-grade at the gasoline pumps with 87 being the regular I've been using. So I guess the next time I buy gas for the 2 strokes, I'll get the premium. And I just bought a new 6-pack of genuine Stihl 2 cycle oil from my dealer and they're not selling a synthetic; higher priced of course, but naturally, they tell me it's better.

 

[MossRoad]

... So I pulled out the manuals...

Now what did you have to go and do that for???

Hee hee!!

 

[Bird]

Now what did you have to go and do that for???

Hee hee!!

I did that because of old age and a bad memory. Incidentally, while the 2 stroke machines call for 89 or higher octane, the Briggs & Stratton engine on my Toro says 85 or higher. I don't even know where you could get gasoline with an octane rating lower than 87.

 

[SkyPup]

I also use the Amsoil 2-stroke synth. mix for chainsaws. There is a discussion about regular, or high test gas for 2-stroke saw over at Arborist.com website. I use high test also.

That full synthetic ester two stroke oil is awesome, I had to rejet all my Huskys and Sthils when I changed over to it because they idled way too fast all of a sudden! I also use it in my Husky weedwackers and outboard boat engines too. The spark plugs now last virtually forever!

Not to mention, ZERO two stroke smoke output makes it extra nice too!

I use it in the racing kart engines too, which is the most extreme two stroke application imaginable at 13,500rpms for 30 minutes at a time nonstop under full load, it rocks!

 

[IH3444]

At the Arborist site the arguement boils down to that hi test has a slight amount of anti-knock additive, thereby there is less auctual gasoline to properly product power, and less fuel means less gas to cool the piston top. I've believed that the smiggen of anti-knock additive is so small it doesn't make a difference. They also speak of fuel mix ignition. Regular gas fires off sooner than hi-test. I'll have to reread all the post over there. I was reading them last winter. Some made sense, so need to be proved. I still use hi-test. Saws never seem to run hot. The racing 2-stroke boats use Amsoil, and claim that they reduce piston skuffing due to just being slicker, and that the pistons stay cooler, thereby not over expanding, and dragging the cylinders at hi rpms. Claim a 17% increase in power after 30 minutes of racing, either off shore, or large lake racing. A buddy has 3 V-6 hanging off his off shore racer, and he uses Amsoil. Those guy tweek that large 2-stroke outboard up to about 1000hp each. If it's good enough for them, it's good enough for my weeeee little saws........

 

[cp1969]

At the Arborist site the arguement boils down to that hi test has a slight amount of anti-knock additive, thereby there is less auctual gasoline to properly product power, and less fuel means less gas to cool the piston top. I've believed that the smiggen of anti-knock additive is so small it doesn't make a difference. They also speak of fuel mix ignition. Regular gas fires off sooner than hi-test. I'll have to reread all the post over there. I was reading them last winter. Some made sense, so need to be proved. I still use hi-test. Saws never seem to run hot. The racing 2-stroke boats use Amsoil, and claim that they reduce piston skuffing due to just being slicker, and that the pistons stay cooler, thereby not over expanding, and dragging the cylinders at hi rpms. Claim a 17% increase in power after 30 minutes of racing, either off shore, or large lake racing. A buddy has 3 V-6 hanging off his off shore racer, and he uses Amsoil. Those guy tweek that large 2-stroke outboard up to about 1000hp each. If it's good enough for them, it's good enough for my weeeee little saws........

That same thing was discussed in Kevin Cameron's column in either Motorcyclist or Cycle World magazine a few years back. He said the highest performance two stroke racing motorcycle engines ran on regular gas because the high octane stuff wouldn't burn quick enough.