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MTD 990 Twactor Guy
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Discussion Starter #1
Finally got the old beastie running, but not for long. It seemed to choke itself out, or something. When I got to looking at the carburetor, I noticed that the knob (?) attached to the choke plate ( I think ) just kind of moved back and forth and doesn't close by itself. ( first picture )

Then, I noticed 2 springs to the left that both seem to be attached to the idle or throttle arm, but they don't do anything either. Where do these get attached? ( Second picture )

I went to the Briggs & Stratton website and downloaded both an Operator's and Parts Manual, but neither was any help. This is a B&S 326437 16 hp.

Thanks for any help you can give!
Rich:thanku:
 

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First picture is throttle if you look right below that at about 5 o'clock that is the choke and those springs are or need to be hooked to something solid that is the governer lever they are hooked to hope this helps
Doug
 

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The springs appear to be set correctly, and yes, their normal mode of operation would be within the "don't do anything" department.

The "this is the lever that's moving" is the throttle valve. When the engine is running well that will be sorta teetering halfway through its motion. There's no need to fiddle with that screw on it.

The lower arm, which the springs hook onto, is the governor arm. As the engine revs up that arm will try to move clockwise; the springs are there to pull it back up. "Tightening" the springs by moving them farther out on that arm would have the effect of allowing the engine to rev higher. From (extensive) experience with my own engine though I can again almost guarantee that fiddling with them will have no effect.

You can provide "more fuel" by adjusting the main needle valve (angled to the bottom left on the carb) counter-clockwise. You shouldn't need to move it more than a full turn.

Aside from a full disassembly and cleaning I would at least remove the main nozzle (under the needle valve) and inspect that.

http://outdoorpowerinfo.com/repairs/briggs_large_two-piece_flo-jet.asp
 

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MTD 990 Twactor Guy
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Discussion Starter #4
Chagrin -

Thanks for the info and the link - that's just what I needed! I should be able to go on to the next glitch - like a leaky hydraulic cylinder.

Rich

BTW - Did you ever do any more about moving the parking brake to the left, and adding pedals for the trans?
 

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I added a pedal (more like a lever with a knob) but did not move the brake to the left. Works just fine but a little uncomfortable when you need to move at a slow speed -- needs something to rest your heel on.

I'd still like to make both adjustments but at the moment the tractor is 1 hr away from my shop in its work environment and needs to stay there for the summer.
 

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On my 8 HP Briggs with that type Flo-Jet carb,it also has a long spring about 6" long that is mostly straight wire,with about an inch of coils on one end--it hooks to the carb throttle lever on the engine side of the carb,and to the govenor arm below it,same place the solid linkage goes--it evidently just puts tension on the levers,and takes up any slop in the holes in the levers the linkage hooks into--my engine surged up and down like a yo-yo,till I added that spring,the holes in the levers were pretty sloppy..
 

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The springs are there to buffer the connection between the governor and the throttle valve to keep the engine running at an even RPM. You'll notice that the throttle cable is not rigidly linked to the throttle valve; it works through the springs and governor arm in order to achieve the final fuel rate.

Yes, the throttle cable could be rigidly linked to the throttle valve, but if it were your engine would both surge and slow down heavily when under load.
 
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