[AT] Super M hard to start

[Stephen Offiler]

Fresh fuel is important (for a number of reasons) but here my main point is
that "winter fuel" is literally a different blend from the refinery which
has a higher volatility than "summer fuel".

Strong spark at the right time is also important.

Choke (mixture enrichment) is necessary on a cold engine because fuel
condenses out of the mix when it hits cold surfaces and results in lean
mixture.  Too much cranking without firing leaves a lot of raw gas sloshing
around.  For this reason, it might be best to use low-ish throttle settings
on a cold engine.

I cheat with an unlit propane torch in the intake stream.  Propane doesn't
condense to liquid on cold surfaces (not much anyway) and it also has a
pretty wide combustible range vs gasoline.


Steve O.

On Thu, Feb 6, 2020 at 4:38 AM Cecil Bearden <crbearden at copper.net> wrote:

> This may not be relevant, but I will throw it out there.  My 2017 Polaris
> Ranger would take 10 minutes of cranking to start below 40deg.  Ether would
> help a lot.  I posted a message to the ranger forum and was told to quit
> using the premium unleaded no ethanol gas.  I switch to 87 octane no
> ethanol and it starts after turning over 3 times at 30 degrees.  It would
> be worth trying for winter.    Premium does not evaporate as well as the
> lower grades.
> Cecil
> On 2/5/2020 8:24 PM, Indiana Robinson wrote:
>
> Hi Dean:
> My Super M and Super MTA both tend to be cold natured at start up and when
> working hard prone to dieseling at shut down. Both have thin-wall sleeves
> and oversized pistons. To start up "cold" I typically open the throttle
> maybe about 5 % or less and use the choke heavily. For the dieseling I keep
> the idle speed backed off so that the throttle plate shuts completely when
> I shove the lever all the way forward. I keep a small paint mark on the
> quadrant back a few notches as an idling setting. They can't diesel if they
> can't get any fuel.  :-)  It has always served me well.
>
>
> .
>
> On Wed, Feb 5, 2020 at 8:29 PM Dean Vinson <dean at vinsonfarm.net> wrote:
>
>> My Super M is hard to start in cold weather.   It always does start,
>> eventually, but if the weather is cold it’ll take maybe five or six or
>> eight attempts, with each one resulting in a few pops or a second or two of
>> running before it dies.   I always think I just need to find the right
>> amount of choke vs throttle, but I don’t know whether I’m really finding it
>> or whether the engine just gets warmed up enough by the repeated attempts
>> that finally it settles down and is just plain ready to start.   In warm
>> weather it typically fires right up with no hesitation.
>>
>>
>>
>> 12 volt battery is well charged, and a few years ago I had the starter
>> rewound for 12 volts, so there’s no shortage of cranking power and it turns
>> the engine over nice and fast (but not crazy fast like it used to with the
>> 12V battery on the original 6-volt starter).
>>
>>
>>
>> It does have pretty high compression, resulting I assume from a rebuild
>> shortly before I bought the tractor ten years or so ago, and which helps it
>> put out about 55 hp on the dyno.  I can’t remember the compression numbers
>> right now, but I remember checking compression after buying the tractor and
>> thinking “Wow, those are some high numbers, and all four cylinders are just
>> about dead-on equal.”   When hot the engine typically diesels at shut-down
>> unless I let it sit and idle for several minutes, so I’m wondering if the
>> hard cold starting is related.
>>
>>
>>
>> Anybody have similar experiences or recommendations?   The other thing I
>> was wondering is if maybe the non sequitur is out of adjustment, but I
>> can’t find the factory specs for it in the service manual.
>>
>>
>>
>> Dean Vinson
>>
>> Saint Paris, Ohio
>>
>>
>>
>>
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>
>
> --
> --
>
> Francis Robinson
> aka "farmer"
> Central Indiana USA
> robinson46176 at gmail.com
>
>
>
>
>
>
>
>
>
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