40:1 vs 50:1 mixed fuel

quote:

---

Just wondering if this is necessary.

---

I've been mixing 2 stroke fuel for small engines by sight for 20 years. Have equipment that's 15 or so years old that operate just fine. Use one can and mix it to the richer blend. A little more blue smoke isn't going to hurt anything.

There was a premix at home Depot I think that said you could use it for both. Not sure how or why.

quote:

---

I have cans for both but ran out of 50:1. I used 40:1 in my 50:1 equipment with not issues.

---

I don't know about chainsaw duel and weed eater fuel, but most Mercury outboards with oil injection supposedly use 50:1 at wide open speed and lower ratios (less oil) at lower engine rpms.

So I guess if you run 50:1 mix in an engine that calls for 40:1, you could just make sure you don't run it at full throttle ?

I run 32:1 in just about all my lawn equipment. Years ago they started calling for less oil in the gas but that was to appease government's stricter emissions at the expense of the equipment owner. Engines have a shorter service life with less oil in the gas but they pollute a little less. Some of my really old stuff calls for 25:1. I don't skimp on oil.

So what if it smokes a little more?

ETA you will not hurt anything by running more oil, you will however lean out the air to fuel mixture slightly. This is because you have a slight increase in oil and a slight decrease of fuel to mix with the air in the carb. The engine may feel a little more snappy or you might develop a slight lean bog, depending on air temps. You can richen the carb circuits to account for this by turning the screw outwards

My dad taught me to just mix everything 32:1 and it's worked out ok.

quote:

---

So what if it smokes a little more?

---

Until it cokes up the exhaust port and spark screen then stops running due to a scored cylinder/piston or blocked screen.


50:1 is fine for anything that could run 40:1, modern synthetic mix oils are vastly improved over the old stuff. Oil lubricates but fuel cools and that's why you run leaner mix ratios when you can. I use Echo Red Armor and Stihl Ultra HP oils in my equipment, all at 50:1 and the pistons, rings, spark plugs look great with zero carbon build-up.

I've thankfully reached a point in life where I don't need to premix anything. My weedwhacker is the only 2 stroke engine I have left and I just buy 50:1 Trufuel for it. I go through a can a year.

What ever mix you decide to run the equipment has the have the carb set for it.

I run 40:1 in my work saws, race saws get 32:1, and nitro saws get 24:1. Gotta set it up for what you want to run

I run "looks close enough" ratio and all the same for all the engines.