I have a few two-stroke lawn equipment tools that use different gas/oil rat
ios. What is it in the design of a two-stroke engine that requires a certai
n ratio? Is it the compression ratio? I googled around but couldn't find a
good explanation on why the weed whip needs 50-1 and the chain saw needs 40
On Saturday, March 26, 2016 at 8:57:33 AM UTC-5, Pavel314 wrote:
atios. What is it in the design of a two-stroke engine that requires a cert
ain ratio? Is it the compression ratio? I googled around but couldn't find
a good explanation on why the weed whip needs 50-1 and the chain saw needs
It must have to do with design tolerance or materials used...unless you hav
e an old 2-cycle where the oil additives were not as good as today. If you
only have those 2 mixes...go with the 40:1 on both.
that use different gas/oil ratios. What is it
in the design of a two-stroke engine that
requires a certain ratio? Is it the compression
ratio? I googled around but couldn't find a good
explanation on why the weed whip needs 50-1 and
the chain saw needs 40-1.
When I took a small engine course years ago, I asked
the same question. The teacher said the engines are
not at all fussy. As for me, I run 32:1 in everything.
Figure I'd rather run rich than lean. Lawnboy likes
to use the special non smoking oil or some such thing.
I've not tried a Lawnboy engine for anything, not sure
it's needed there either.
I suspect the difference in ratio is based on the
machining and manufacturing -- hard versus soft
steel for example.
On Saturday, March 26, 2016 at 11:10:59 AM UTC-4, Stormin Mormon wrote:
IDK either, but I think there is a trend over time, no?
That new engines use less oil? Are there still new engines
that use 32:1?, etc. Less would be better to reduce emissions.
And the new oils are better, synthetic, so less can be used.
Echo says the mix oil used in their 2 cycle engines has to meet JASO FD,
ISO-L-EGD specs or the warranty is void. Their (pretty expensive) brand
of oil does-- but so do some generics and other less expensive brands.
“Let the one who has no sword sell his cloak and buy one.”
- Jesus (Luke 22:36)
Don't recall what I was using but shop told me that it was reason I was
having problems that I brought to them. I did not want to inventory
different mixes so used the same in all. I had two Lawnboys, neither of
which would start one spring so I traded them both in for a 4 cycle Honda.
Echo also states in their manual:
Echo premium Power Blend X TM Universal 2-Stroke Oil may be mixed at
50:1 ratio for application in all Echo engines sold in the past
regardless of ratio specified in those manuals.
Small engine shop I use said that if I use the pre-mixed fuel (no
alcohol) I can use the 50:1 mix across the board and all will be well.
The saw is likely older, and works harder. The "older" relates to the
oils available at the time of manufacture. I'd likely use 50:1 oil
mixed at 45:1 for both as a matter of expediency.
Don't use oil designed for 40:1 at 50:1
On Sat, 26 Mar 2016 13:52:22 -0400, email@example.com wrote:
I've seen some of these oils that say they are good for ALL 2cycle
engines. Just add contents of the bottle to a gallon of gas (or 2
gallons, or whatever is marked on the bottle).
I've never used that stuff, buy wanted to mention it. I rarely use any
2cycle engines anymore. I replaced most of them with electric models,
such as chainsaw and weed whacker. Far less hassle getting them to
start, and having to worry about gas getting stale, and trying to run
them dry after use and all of that trouble....
However, I always believed in adding a little more oil, rather than
less. It might smoke a little, but at least it's well lubricated. If the
OP only has a 40 to 1 and a 50 to one. I'd just use the 40 to 1 in both.
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