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The Autochoke Side Project


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  #1  
Old 11-29-2017, 08:05:20 PM
Newoldstock Newoldstock is offline
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Default The Autochoke Side Project

I started to build something here I thought might be of interest.
I have been fascinated by all these new mowers with very good choke systems and frustrated by the lack of a decent automatic choke for clones so I decided to graft the Kohler system to mostly Chinese clone of mixed parts from a generators and utility engines.
I want to build something that will start automatic with just a simple stop run switch to activate it.

First mock up.
As you can see I need to make some exhaust parts and some linkages will need to be worked on.
I might have some governor issues from the looks of things.
But its a start...
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Old 11-30-2017, 12:48:59 AM
gdstew gdstew is offline
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Default Re: The autochoke side project

Do not take this wrong, I like people trying new ideas. Maybe a less complicated system would be a simple primer bulb hooked to the carb vent????
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Old 11-30-2017, 06:27:51 AM
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Elden DuRand Elden DuRand is offline
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Default Re: The autochoke side project

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Originally Posted by gdstew View Post
Do not take this wrong, I like people trying new ideas. Maybe a less complicated system would be a simple primer bulb hooked to the carb vent????
Now, what's the fun in that??
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Old 11-30-2017, 08:25:50 AM
Newoldstock Newoldstock is offline
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Default Re: The autochoke side project

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Originally Posted by gdstew View Post
Maybe a less complicated system would be a simple primer bulb hooked to the carb vent????
That might work if I was there to prime the system for a start, but I have something little more challenging in mind for this.

It must start on it's own accord.
Its primary purpose will be a supplementary power supply for some inverters and a UPS.
I thought about making a fully adjustable 3 stage battery charger option and maybe a portable inverter generator.
But first it has to be able to start automatically, the rest I can add later.

Its kind of complicated looking isn't it?
What you see is a complete choke system from a XT149 mower adapted to a clone carb.
Kohler abandoned this system several years ago because of its complexity.
That they use now has no vacuum choke break but a simpler mechanical linkage connected to the throttle.
I could have used that, but I felt it might not work with with my automatic idle control.


Here is the parts break down if you interested.
https://www.partstree.com/parts/kohl...g/fuel-system/

Bugger I have to go to work now.
Have a nice day guys...
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Old 11-30-2017, 01:24:44 PM
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Default Re: The Autochoke Side Project

Briggs & Stratton used a system recently that held the choke closed with a fairly weak spring when the engine was at rest (shut off). A thermo operated lever attached to the muffler along with an air vane lever would open the choke when the engine started. The way I understood it to work, the air vane wanted to open the choke immediately on starting, but the thermo lever held back until it saw some heat.
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Old 11-30-2017, 02:05:32 PM
gdstew gdstew is offline
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Default Re: The Autochoke Side Project

we replaced several of those thermostat assys on equipment 2-3 years old
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Old 11-30-2017, 04:39:14 PM
Newoldstock Newoldstock is offline
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Default Re: The Autochoke Side Project

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Originally Posted by gdstew View Post
we replaced several of those thermostat assys on equipment 2-3 years old
I was aware of a lot of problems with this system.
The donor mower that I stripped looked almost new and my best guess it it was given up on or damaged for some reason.
I tested all the parts out and the by metal spring moves as well as the vacuum pull off works.

One things that is absolutely wrong with the Kohler autochoke is there is no adjustment.
I plan to address that as you can see I already removed the backing on the thermostatic spring and will make a holder for it that lets you turn it "rich - lean"
as required.
I might even do something with the linkage for the pull off if I think it needs some adjustment, but for now I think its OK.

I need to do something with the muffler.
If you look close I have it mounted upside down in the picture.
Maybe I re-weld and rework it that way, or I could make something up from scratch with an empty propane cylinder, or I could use a generator muffler but its very large.

Its cold and raining outside and I don't feel like warming up the shop so I think I will just type and ponder the exhaust today
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Old 11-30-2017, 05:22:32 PM
Newoldstock Newoldstock is offline
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Default Re: The Autochoke Side Project

Most standby units use some sort of a choke system.
These first two use a bymetal spring to hold the choke partly closed until warm and a solenoid to pull it completely closed while cranking for full choke.
A Generac uses this part

Onan, Kohler and Chrysler used this.


Some use manifold vacuum only
Briggs used a chamber and diaphragm to pull the choke open against a weak spring.
This was a simple idea on the Pulsajet carbs because the diagram and chamber were already there for the fuel pump.
They simply added another chamber spring and rod for the choke


I am using a combination of vacuum and thermal spring like most later automotive application used because I feel its a bit less likely to flood out a warm engine.
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Old 11-30-2017, 11:14:43 PM
Newoldstock Newoldstock is offline
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Default Re: The Autochoke Side Project

The Generac part is electrically heated and electric operated.
The divorced choke I am using is manifold heated and vacuum operated.
I think I rather go with the old timey parts on this one.
And as a bonus Kohler parts are clone Honda so all the rods linkages and bell crank were made to fit the carb.
The Generac might have been more work.

I think I am going to make a simple packed stuffing muffler out of a propane cylinder for this some other time.
I will rework the Honda part for now and live with the noise.
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Old 11-30-2017, 11:44:24 PM
Thaumaturge Thaumaturge is offline
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Default Re: The Autochoke Side Project

Looking into replacement for my autostart Kohler carb, I looked into adapting a Chinese scooter carb. Rather than chokes they have a solinoid that opens a separate rich fuel port. Would need a shutoff timer, but would sure be cheaper. Can even still get fully adjustable carbs. Available from 50cc up to 750cc sizes.
Doc

(Seems a bit bland for my 3,000th post... ah well.)
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