2 stroke longevity - how many hours

[Tiger Small Engine]

Two strokes generally get a bad rap because of oil type and oil mixing issues. A quality air cooled two stroke oil is necessary and the ratio is important as well. As background I've flown two stroke powered Ultralight aircraft for over 30 years. The Rotax guys that didn't have oil injection always thought that more oil in the mix was better.....all they did was shorten the time between overhauls, coke up the top of the pistons, fill the exhaust port with carbon, foul the plugs and lock the rings in place. I went with a 100:1 mix for all my engines, not just UL but trimmers, chain saws, blowers, etc., and the plugs all looked like four stroke engines and never needed to be replaced. Rings stayed free, crosshatch was very visible after 800 hours and no decarbonizing was ever needed. The amount of oil is vanishingly small because of the roller and needle bearings in modern two strokes. If this were a really old plain bearing engine you'd need way more oil in the mix than 100:1 could provide.The brand of 100:1 oil is not important as long as it has a good name behind it. The other advantage in my case was full instrumentation for EGT and CHT. Two strokes do not like getting a too lean mixture. In your case it's simply learning to listen to the engine as you screw in the high speed needle to hear it break over from a four stroke to a two stroke. It's a learned skill that isn't magic, just a practiced ear.

Two strokes are louder, and smoke. Those are probably the two main reasons that many manufacturers have gotten away from them a lot.

Do not mix oil to fuel at anything except 50:1. You can do your research. You can argue. You can disagree. 50:1 is what is recommended.

If taken care of, two stroke equipment will last many years, especially if it is quality brand to start with.

 

[RevB]

Two strokes are louder, and smoke. Those are probably the two main reasons that many manufacturers have gotten away from them a lot.

Do not mix oil to fuel at anything except 50:1. You can do your research. You can argue. You can disagree. 50:1 is what is recommended.

If taken care of, two stroke equipment will last many years, especially if it is quality brand to start with.

And before 50:1 it was 20:1 with plain motor oil, then it went to 25:1, then 30:1 with castor oil, then 40:1 with specially formulated two stroke oil that served both water and air cooled. Then 40:1 with oils specifically formulated for water or air cooled. Then 50:1......and then everything stopped. No more progress. Oils couldn't get any better so they quit. Same for metalurgy and bearings. Everybody just gave up.

 

[srwa]

I have a John Deere chain saw I bought new over 40 years ago. Never drained the fuel or used additive. Starts and runs like new.

I'm a "touch prejudice" regarding 2 cycles. First "run in" with them was in the late 40's early 50's. Was not a good experience.


I was born in March of 37......1937.............do the math.

 

[GearHead36]

As a mechanic, I wish everything I owned was a 2-stroke, even the cars and truck!

Yeah, but they would get 3 mpg.

I've had good luck with 2-strokes. I raced 2-stroke dirt bikes in the 70's. Since then, I've had numerous 2-stroke trimmers, leaf blowers, chainsaws, etc. I'm just a homeowner, and I've never operated a 2-stroke engine commercially, but I've never had one die. For power equipment that I'm carrying (chainsaw, trimmer, etc), it's 2-stroke all the way for me. They're lighter than their 4-stroke counterparts for the same power, so I can carry it longer, and get more work done.

Now my riding mower is different. It has a 27hp EFI engine, and two 3.5gal fuel tanks. It takes 2 hrs to mow my yard, and I can mow it at least 3 times on that much fuel. If it were a 2-stroke, it would probably use all 7 gallons each mow.

Are 2-strokes fragile, temperamental, finicky? I don't think so. Maybe slightly more than a 4-stroke, but if maintained, both will be reliable. If ethanol fuel is left in them over the Winter, it won't matter whether it's a 2 or 4-stroke. Neither will start, and both will need a carb cleaning or rebuild. In 2011, I bought a mower with a B&S flathead engine, and an Echo 225 PAS system. I liked the Echo PAS system because it meant only one engine to maintain for all my handheld OPE. It also meant that there wasn't any piece of equipment that didn't get started for weeks. The Echo has been run, I'd say, about 75% as much as the B&S, and they both still run like new today, 14 yrs later.

 

[Smithsonite]

My RD350 consistently gets 38 MPG. I spent a LOT of time tuning.

 

[GearHead36]

My RD350 consistently gets 38 MPG. I spent a LOT of time tuning.

OK, but that RD weighs (according to Wikipedia) 342lbs. A truck weighs over 10X that. Although I have to say, that must be a VERY well tuned RD. My 4-stroke bikes never got mileage that good.

 

[Smithsonite]

It also has MANY modifications. Carb mods, reeds, porting, pipes, higher compression, different pistons, crank balanced, etc.. I got the squish set within .001" of where I wanted it, and run the timing advanced farther than anyone else with the same bike dares. Runs absolutely perfect. I figure around 70HP at the crank, maybe more. She rips!