40:1 in my new saw

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Best number 1 rule, don`t loan out any chainsaw cheap or expensive ones unless you enjoy repairing them for free. If I were to loan out a chainsaw then I would be ready to kiss it goodbye. The loan out stories I could tell would take up far too much space, ruined engines, ruined bar and chains, broken body parts and handles, loaned out saws go through hell and back from what I have seen.
 
When someone ask me to borrow a saw i simple ask them if I can borrow their wife or girlfriend …. They give the wtf look ,and I say we’ll you wouldn’t lend them out I sure as hell ain’t lending any of my chainsaws out
Depends on who your talking to, what kind of saws do you have? I know a few guys that would send their wives your direction without even second guessing the decision.
 
There is nothing magical about a particular mix ratio. Years ago when I took over the operation of a small repair shop they had about 6 different cans of different mix ratio fuel and I did away with most of them. Kept the 32:1 and the 50:1 and told the customers they should be using one or the other. But back then everything had an adjustable carburetor so you could richen them up enough that they ran well and still provided good lubrication. That all changed when because of EPA rules carbs became either non adjustable or had limiter caps to prevent "tamperin". So what happens when you run 40:1 in an engine that is supposed to have 50:1? I know it's difficult to believe but you actually lean out the mixture which is most likely already too lean and instead of providing the engine with additional lubrication you are causing it to get less and also run hotter. It changes the viscosity when you add more oil.
I know, I know. Doesn't seem like it would make much difference but Stihl had a video years ago that showed what happened to engine temperature and exhaust temperature when you changed Only the mix ratio on a two cycle engine. Decades ago I had a Suzuki RM250 motocrosser that I added extra oil to because I wanted to make sure it had good lubrication even though at some point the mechanic warned me not to. Yup, I seized it. He was right but I never knew why until I heard about that Stihl video.
So - DON'T use more oil in your mix unless you can richen up the mixture at the carburetor!
 
There is nothing magical about a particular mix ratio. Years ago when I took over the operation of a small repair shop they had about 6 different cans of different mix ratio fuel and I did away with most of them. Kept the 32:1 and the 50:1 and told the customers they should be using one or the other. But back then everything had an adjustable carburetor so you could richen them up enough that they ran well and still provided good lubrication. That all changed when because of EPA rules carbs became either non adjustable or had limiter caps to prevent "tamperin". So what happens when you run 40:1 in an engine that is supposed to have 50:1? I know it's difficult to believe but you actually lean out the mixture which is most likely already too lean and instead of providing the engine with additional lubrication you are causing it to get less and also run hotter. It changes the viscosity when you add more oil.
I know, I know. Doesn't seem like it would make much difference but Stihl had a video years ago that showed what happened to engine temperature and exhaust temperature when you changed Only the mix ratio on a two cycle engine. Decades ago I had a Suzuki RM250 motocrosser that I added extra oil to because I wanted to make sure it had good lubrication even though at some point the mechanic warned me not to. Yup, I seized it. He was right but I never knew why until I heard about that Stihl video.
So - DON'T use more oil in your mix unless you can richen up the mixture at the carburetor!

Debunked many times. Decades ago, the bean oil of the day didn't burn, dripped out the muffler instead, and more oil did lean out the fuel/air mix. Modern oils burn, and contribute to the fuel load. More oil = richer fuel/air mix.

I agree with your last sentence - tune for whatever you're running. Proper tuning makes most of this a moot point.
 
Debunked many times. Decades ago, the bean oil of the day didn't burn, dripped out the muffler instead, and more oil did lean out the fuel/air mix. Modern oils burn, and contribute to the fuel load. More oil = richer fuel/air mix.

I agree with your last sentence - tune for whatever you're running. Proper tuning makes most of this a moot point.
More oil does equal a leaner fuel to air ratio. So does a decrease in temperature, an increase in load and a few other factors which have a much greater effect. Something that's lost on the guys the ******** about a percent more oil leaning out their saws.
 
There is nothing magical about a particular mix ratio. Years ago when I took over the operation of a small repair shop they had about 6 different cans of different mix ratio fuel and I did away with most of them. Kept the 32:1 and the 50:1 and told the customers they should be using one or the other. But back then everything had an adjustable carburetor so you could richen them up enough that they ran well and still provided good lubrication. That all changed when because of EPA rules carbs became either non adjustable or had limiter caps to prevent "tamperin". So what happens when you run 40:1 in an engine that is supposed to have 50:1? I know it's difficult to believe but you actually lean out the mixture which is most likely already too lean and instead of providing the engine with additional lubrication you are causing it to get less and also run hotter. It changes the viscosity when you add more oil.
I know, I know. Doesn't seem like it would make much difference but Stihl had a video years ago that showed what happened to engine temperature and exhaust temperature when you changed Only the mix ratio on a two cycle engine. Decades ago I had a Suzuki RM250 motocrosser that I added extra oil to because I wanted to make sure it had good lubrication even though at some point the mechanic warned me not to. Yup, I seized it. He was right but I never knew why until I heard about that Stihl video.
So - DON'T use more oil in your mix unless you can richen up the mixture at the carburetor!
It's highly unlikely adding more oil burnt up your RM250. The specced a 32:1 ratio in the first place.
 
More oil does equal a leaner fuel to air ratio. So does a decrease in temperature, an increase in load and a few other factors which have a much greater effect. Something that's lost on the guys the ******** about a percent more oil leaning out their saws.

I've switched from 40:1 to 50:1 and had to richen my tune. Switched back to 40:1 and had to lean out my tune.
 
I've switched from 40:1 to 50:1 and had to richen my tune. Switched back to 40:1 and had to lean out my tune.
If there was a change it wasn't from what you suggested.
A motors tuning requirements are based on the amount of gasoline vapor present in the combustion chamber prior to the plug firing. Liquids fuel and oil do not count toward this, which is why when cold a two stroke requires a choke or primer to even start. With little fuel in a gas state it takes alot more fuel traveling into the motor to produce a air fuel mixture that will light off.
 
If there was a change it wasn't from what you suggested.
A motors tuning requirements are based on the amount of gasoline vapor present in the combustion chamber prior to the plug firing. Liquids fuel and oil do not count toward this, which is why when cold a two stroke requires a choke or primer to even start. With little fuel in a gas state it takes alot more fuel traveling into the motor to produce a air fuel mixture that will light off.

Happened on the same day, all within minutes of each other. Same temp, humidity, altitude, etc. It was linked to the fuel. You tell me what the difference was.
 

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