Re: rec tech mower

On Sun, 13 Apr 2025 08:53:26 -0500, AMuzi <am@yellowjersey.org> wrote:

On 4/12/2025 5:03 PM, Jeff Liebermann wrote:

On Sat, 12 Apr 2025 07:51:21 -0500, AMuzi <am@yellowjersey.org> wrote:
 

On 4/12/2025 1:41 AM, Jeff Liebermann wrote:

On Sat, 12 Apr 2025 13:05:24 +0700, John B. <slocombjb@gmail.com>
wrote:
>
(chomp)

As an aside, most of the problems with small engines being stored for
long periods of time can be caused by the fact that much "Gas Station"
gas contains Ethanol. It's worth it to search for "pure gasoline" gas.
https://www.buyrealgas.com/states.html
https://www.pure-gas.org/

>
True.  Here's a video that explains what's happening:
>
"The Ugly Truth Why Gas Station Fuel Is Bad For Small Engines"
<https://www.youtube.com/watch?v=Wvps2gF0Sdo>
>
I wasted some time and effort trying to remove the ethanol from retail
gasoline.  It can be done, but the results are not very good.  The
problem is that ethanol is an octane booster.  Take away the ethanol
and the octane rating of the gas goes down.  If I start with regular,
the octane rating ends up so low that the engine might knock.
Actually, modern engines change the timing advance so that the engine
just barely knocks.  It doesn't ping and sorta runs, but not very
well.
>

I believe that some airfields that cater to old fashioned propeller
airplanes may also stock it.

>
<https://en.wikipedia.org/wiki/Avgas#93UL_(Ethanol-free_93AKI_automotive_gasoline)>
Ethanol free gas in a car probably won't hurt the car engine. However,
there is no authoritative consensus as to whether it's a good or bad
idea.  Try sampling some articles on the topic:
<https://www.google.com/search?q=using%20ethanol%20free%20avgas%20in%20car>
I have little experience and no opinion.
>

>
+1
Since none of my autos has computer controls, I pay
attention to fuels* and for one engine in particular only
no-ethanol premium.
>
*My engine guru says most modern autos can digest a range of
fuels, as the computer adjusts spark timing and injection to
whatever it is, but small engines don't have those.

 
I beg to differ somewhat.  Chainsaw engines for the homeowner market
don't have computerized timing.  However, modern commercial chainsaws
certainly do have automagic timing adjust features.  For example, the
Stihl M-Tronic system:
<https://www.stihl.co.uk/en/stihl-technology/ignition-systems/m-tronic>
<https://www.youtube.com/results?search_query=m-tronic%20stihl>
I haven't worked on one of these saws (yet), so I don't have any
experience with M-Tronic ignitions.
 
Husqvarna has "AutoTune" to dynamically adjust the fuel/air mixture:
<https://www.youtube.com/watch?v=zVyjrn8Oeho>
 
Echo has Slope Advance Ignition 1 through 3 and Digital CDI (Cazapitor
Discharge Ignition) for ignition advance:
<https://www.youtube.com/watch?v=HiMbH3JlASM>

Sounds truncated from sophisticated modern auto computer
systems.

The automagic advance systems are similar.  Build a computer model of
how the output (ignition advance) responds to various inputs (rpm,
fuel flow, temperature, atmospheric pressure, days until the warranty
expires, etc.  Stuff the chainsaw full of sensors that will measure
these.  Add a few limit switched to shut down the saw in case
something goes insane.  If it works, patent it:

"IGNITION ASSEMBLY FOR A TWO-STROKE ENGINE IN A CHAIN SAW"
<https://patents.google.com/patent/FR2635145A1/en>
<https://patentimages.storage.googleapis.com/94/ea/ca/c24446d3092cea/FR2635145A1.pdf>
The above PDF is in the original French.  Looking at the citations at
the bottom of the patent, the original idea came from Bosch, circa
1976.

This is a simpler US version from 1989:
<https://patents.google.com/patent/US4979477A/en
<https://patentimages.storage.googleapis.com/e0/f2/72/ed95d9f9e2d526/US4979477.pdf>

Both patents expired in 2009.  I couldn't find the current replacement
patent.

Patents are technology and legality combined to produce gibberish.
Like oil and water, they don't mix very well.

--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558