Well, there are friends and then there are friends. I have a couple if they burn my saw up so be it.
40:1 in my new saw
- Thread starter Welderman85
- Start date
Help Support Arborist Forum:
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.
Just like the best off-road rig is a rental car, the best stumper and root cutter is a borrowed saw.
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.
Moonbat
ArboristSite Lurker
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!
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.
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.
It's highly unlikely adding more oil burnt up your RM250. The specced a 32:1 ratio in the first place.
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.
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.
Maybe so, but no specifily the oil concentration. Same oil I assume?
That might be a difference. It was Trufuel, just happened to get a quart of 50:1, when I normally run 40:1. They might use a different oil between their mixes.
I switched from 50:1 to 40:1 and didn't notice any difference in the tune. Granted it was a different oil and different day and probably other variables.
In the meantime I have been running 50 to 1 in a LawnBoy for close to 40 years. Hasn't burnt up yet.
Maybe next year. Ya'll are so FOS.
Maybe next year. Ya'll are so FOS.
FOS must mean Full Of Solutions.
LOL
I actually largely agree. While there's definitely best practice, there's also no shortage of ways to skin this cat. Pretty much everyone can mix their choice of oil at their choice of ratio, and have it be the right way.
