If I was going to post content on YouTube I would be sure I knew what the hell I was talking about before I did.
mixing ratios for 2 stroke chainsaws
- Thread starter sawmill sam
- Start date
Help Support Arborist Forum:
I think I detect a little sarcasm!
You must be new to the internet.
Well in this case it’s not an opinion as the video speaks for Itself. I’m not interested in having an online pissing match or throwing insults around, instead what I’d appreciate is the opportunity to learn.
If you or others are willing to share your advice, what way would you suggest I do the test differently to have a different outcome and prove myself / first video wrong? I’ll happily upload it and admit so if it’s the case.
Thats the thing, it is free for all- all you need is a recording device and you can put up what you want- facts are not mandatory nor policed.
You don't realise what's causing what you are seeing. As a result your conclusions are off.
What I suggest you do is start thinking about the variables.
I've said it before, and I will say it again. The vast majority of these YouTube tests are complete garbage.
Thanks for the reply. In my case, the only variable was the oil mix ratio changing.
The load on the engine was the same, the unleaded petrol the same, air temperature the same, run times the same, the time of day was even the same within a few minutes.
Rpm swing from 50:1 to 32:1 was 80 rpm.
What about the temperature of the engine? What about the type of oils used(some oils inhibit combustion)? What about the accuracy of the tach?
Then there is the fact your trying to draw conclusions from a sample of 1 with a result variability of 80rpm, which is less than peanuts.
There are others as well...
Regardless an honest to god sae test was done on this subject and the conclusions where the opposite of yours.
I used it for years and actually was the guy who mentioned it to this site around 20 years ago.
And yes you are absolutely right a good modern oil like Mx2t will burn clean at ratios like 16:1.
I curse Mobil for discontinuing it.
The tach I used is one of, if not the most accurate digital tachs on the market, oil was Amsoil Sabee which people suggest is thicker than many which should show more affect. The engines were ran up to full operating temps before reading rpms. Have you got a link to that video you mention?
Im a former dirt bike guy who had 2 strokes.
If you run 32-1 in them the bottom end bearings last forever, if you run 50 or 60-1 your bearings go after 200 or so hours. It takes a long time for this to show up. Engine builders would do tear down and inspections to see how much oil was left in the crank case, with 50-1 the crank was pretty dry, with 32-1 it was oily.
I run 32-1 in my china saws to keep the bearings lubed up, the piston doesnt care what ratio you run.
If you run 32-1 in them the bottom end bearings last forever, if you run 50 or 60-1 your bearings go after 200 or so hours. It takes a long time for this to show up. Engine builders would do tear down and inspections to see how much oil was left in the crank case, with 50-1 the crank was pretty dry, with 32-1 it was oily.
I run 32-1 in my china saws to keep the bearings lubed up, the piston doesnt care what ratio you run.
Ok, so what's the margin of error?
And viscosity of the oil doesn't matter. It's about volume of oil in the mix and how much gasoline it displaces.
Saber is formulated to run at 100:1. It makes sense that at richer ratios it may inhibit combustion.
You ran the test back to back so by the time you ran the second test the motor would have been warmer internally. This can lead to less charge density and less power. And trust me I am just scratching the surface on the variable involved. Not to mention a sample of one has zero statistical validity.
I never mentioned a video.
Yep.. and when bottom end bearings go in a bike you often don't catch it before the whole motor tears itself up.
You could always do something bizarre like follow the owner's manual.
You could also lunch bottom end bearings as a result.
And every owner's manual I've seen from at least the last 30 years has stated to use a ratio of 40:1 at most. My 1996 KTM 300 EXC dirtbike manual says either 50 or 60:1, but it's less than 40:1.
Yeah, and I'm sure the mix ratio or type of oil was the reason why. Yeah, I believe that.
I think he meant launch, not lunch, but I could be wrong. Kinda makes a difference.
Some time back I was flushing out the bottom end of a 385 & realised that when I transitioned between different mixes I could feel the difference in how freely the crank spun. This lead to a bit of experimentation & what stood out to me was how much of a difference I could feel rotating the crank with a case full of 32:1 vs 50:1.
In heind sight I should have tried it with different oils too.
Tom, as far as real world testing goes, I would set up a motor running at constant load. Once warm set rpm as desired for the 50:1 mix. Then over a period of time (while the motor runs continuously) raise the oil mix ratio up to around 20:1. Then over the same period of time reduce the mix back to 50:1.
Monitor cylinder temperature & rpm throughout.
While you won't be measuring a direct correlation between a specific mix ratio & rpm (as the mix will be varying) you should see a meaningful trend.
Repeat as many times as possible using as many different oils as possible
In heind sight I should have tried it with different oils too.
Tom, as far as real world testing goes, I would set up a motor running at constant load. Once warm set rpm as desired for the 50:1 mix. Then over a period of time (while the motor runs continuously) raise the oil mix ratio up to around 20:1. Then over the same period of time reduce the mix back to 50:1.
Monitor cylinder temperature & rpm throughout.
While you won't be measuring a direct correlation between a specific mix ratio & rpm (as the mix will be varying) you should see a meaningful trend.
Repeat as many times as possible using as many different oils as possible
The Japanese bikes were all 32:1 except for Yamaha which speced 30:1.
