Early Style Auto-Choke for B&S 190cc Engine?

[D@ve]

I inherited a 2008 (according to the bar code) Toro Recycler 675 190cc walk behind mower.
There is no model ID plate on it that I can find anywhere. Definitely nothing above the muffler.
The butterfly valve in the carb is fully open, even when cold.
This engine does not have a thermostat / arm mounted behind the muffler like all the videos I've seen while researching this.
The wire from the carb runs back to an arm mounted on the back of the engine that doesn't seem to have any thermostatic control.
Anybody have an idea how to remedy this and / or find a parts list for this engine / carb?
I've spent hours trying to find info on this design and have had no luck.

 

[Rivets]

This manual should answer most of your questions. Post back if you have more questions. https://drive.google.com/file/d/0B6NaqjIxWV1ycG8wd0s3Z2Q2X00/view

 

[heamicdan]

this is what i have---have to use a shot of gas in carb ---everyone keeps telling me it has the thermostat but it does not! no signs of it anywhere----been looking to see if there is a special carb---mine has run perfect for years and i like it---just now this year it will not autochoke

 

[Rivets]

There is no choke on the carb pictured. More than likely you should have a primer built into the air filter backing.

 

[Scrubcadet10]

that carburetor does not have the auto choke. what you're seeing is the governor arm, governor link, and throttle shaft. which controls engine speed. that carburetor goes with the a primer type airbox ( either 593942 or 795259 depending on the date code)
It appears to be a 12000 series Quantum, but your specific engine model number will be stamped on the metal blower housing above the spark plug or muffler.

how the primer works is when you press the bulb, it forces air through channel made into the back of the airbox, that channel ends where there is a hole in the carb that goes into the bowl, air being forced into the bowl forces fuel out of the main jet and into the intake. sometimes that air box will warp and the gasket will not seal, letting the air out, instead of going to the carb. sometimes you can use 2 of the gaskets to fix it.
there is also a little screen in the airbox right behind the primer bulb, in the channel that can get clogged with dust and cause the primer to not work properly.

like these,

 

[heamicdan]

that carburetor does not have the auto choke. what you're seeing is the governor arm, governor link, and throttle shaft. which controls engine speed. that carburetor goes with the a primer type airbox ( either 593942 or 795259 depending on the date code)
It appears to be a 12000 series Quantum, but your specific engine model number will be stamped on the metal blower housing above the spark plug or muffler.

how the primer works is when you press the bulb, it forces air through channel made into the back of the airbox, that channel ends where there is a hole in the carb that goes into the bowl, air being forced into the bowl forces fuel out of the main jet and into the intake. sometimes that air box will warp and the gasket will not seal, letting the air out, instead of going to the carb. sometimes you can use 2 of the gaskets to fix it.
there is also a little screen in the airbox right behind the primer bulb, in the channel that can get clogged with dust and cause the primer to not work properly.

View attachment 56608 like these, View attachment 56609

if its like mine it has no primer anywhere ----no auto choke --- no manual choke no manual throttle no nothing lol

 

[Scrubcadet10]

^ have yet to see one like that.

 

[Rivets]

I’ve seen it a couple of times. Only when a DIY guy would replace the carb with one that is not made for that particular engine, but it did have a throttle. If you have a carb with no choke or throttle I would really like to see it, as that would go against everything I know about and taught my students over the last 50 years. There is one exception, that is what was called a carb on the very old “hit and miss” engines. Heamicdan, would you please post some pictures so we all can learn something today?

 

[D@ve]

Wow, thanks for all the responses! As a newb to this forum I was hoping for 1 or 2 responses, especially on what I thought was a pretty obscure issue. In regards to some of your answers, my mower does have a primer bulb, which unfortunately seems to have little effect during cold starts, although I'll give that more attention. I do know that a shot of starter fluid into the carb caused it to fire right up. Once it's warm it starts on the first or second pull. I just don't understand why the linkage to the butterfly valve currently causes it to be fully open when cold. The mower has no manual throttle or choke controls. Seems like it should either be a manual operation or controlled be a thermostat. Thanks again.

 

[Scrubcadet10]

Wow, thanks for all the responses! As a newb to this forum I was hoping for 1 or 2 responses, especially on what I thought was a pretty obscure issue. In regards to some of your answers, my mower does have a primer bulb, which unfortunately seems to have little effect during cold starts, although I'll give that more attention. I do know that a shot of starter fluid into the carb caused it to fire right up. Once it's warm it starts on the first or second pull. I just don't understand why the linkage to the butterfly valve currently causes it to be fully open when cold. The mower has no manual throttle or choke controls. Seems like it should either be a manual operation or controlled be a thermostat. Thanks again.

the governor sits at wide open when off, and when the engine starts, centrifugal force acts on the flyweights on the governor gear inside the engine, which in turn moves the governor arm and throttle to the governed RPM (and can be changed by increasing tension on the governor spring, the governor tries to slow the engine down, while increasing tension on the governor spring increases RPM), generally about 3200 or 3400 rpm. depends on the application. all of those engines like that (that i've seen) sit at WOT when not running.

you can see the governor spring in your picture you attached. you can increase tension on it and that will increase the RPM's.
the only thing that will be affected by a thermostat is the auto choke, IF you had an autochoke system, which you don't.
an autochoke carb will have 2 shafts in it. throttle, which is closest to the engine, and choke shaft, which is closest to the air cleaner.