Briggs 129802 Manual Choke Sticks (external mechanism)

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I have a 190cc B&S IC 129802 series mower, bought new in around 1998-9 (from memory). It's a great workhorse, stored in a dry garage, but hasn't been serviced for a while. Recently developed a problem when trying to put the throttle into start: the choke "throw" mechanism gets stuck half-way. Throttle lever range is
off -> mid-run -> flat out -> choke / start
Putting it into the start position it gets stuck with the choke half-way. The individual parts move freely and smoothly (to my eye / hand), they just don't seem to want to work together any more. Checked for rough edges, can't feel any - doesn't mean they aren't there, just can't feel them. Any suggestions?

If the pics attach as intended they show run, choke stuck half-way, and start positions in that order.

Update: when it's stuck, I can manually complete the "throw" by giving the choke's black triangle a gentle nudge with a screwdriver. It then starts easily, and afterwards throws back into the run position by moving the throttle lever on the handle.
 

Attachments

  • Choke 1 - run position - 20260531_131721.jpg
    Choke 1 - run position - 20260531_131721.jpg
    1.9 MB · Views: 8
  • Choke 2 - halfway on - 20260531_131730.jpg
    Choke 2 - halfway on - 20260531_131730.jpg
    2.2 MB · Views: 8
  • Choke 3 - start position - 20260531_131739.jpg
    Choke 3 - start position - 20260531_131739.jpg
    2.1 MB · Views: 8
Last edited:
Have you tried cleaning it with brake cleaner and compressed air? Then adding some type of lubricant?

I’d guess there is a bit of dirt/dry that is stopping the movement?
 
Hey, thanks for the suggestion - yeah it looks a bit grotty. I haven't heard of using brake cleaner (file that away for future :)), however, I did get rid of the worst and have lubed all of the pivot points with something similar to WD40 - it's made for a heavy industrial environment and cleans joints as well as lubes. The two parts that touch are normally dry, whilst you can only see them end-on in this view, they have been cleaned and were lubed as well.
 
The brake parts cleaner doesn’t cause seals to swell like choke and carb cleaner. The compressed air may help to remove the dirt. Light drop or two of sewing machine or gun oil can help. Unfortunately it too will attract dirt and dust. I’ve seen some individuals use a graphite power. I believe a good cleaning and lube will keep it working correctly another few years-20-30
 
Cleaned it as best can be done whilst assembled. Ended up using INOX MX3 to lubricate it, it's non-petroleum based and can be used on neoprene so it's a safe option for seals & bushes. Ta-da, we have a working choke - thanks.
 
Sorry, the choke shaft is rough and ground in with dust sediment. You can try polishing the shaft stem, but this likely needs a carburetor.
 
andrewslarge said:
Have you tried cleaning it with brake cleaner and compressed air? Then adding some type of lubricant?
Click to expand...
Hold up on that car wash gentlemen (Smokey and the Bandit).

What happens if you spray any flavor of oil on a lawn mower? It will collect dirt, grass and grit right? Grit will wear out everything it touches.

How about foaming glass cleaner and shop air? Maybe use the wife's toothbrush and scrub it down a little?? Much cheaper and way less toxic than brake cleaner.
 
Nice film reference. Given the price of divorce lawyers, using my other half's toothbrush would be a very expensive option ;). Thanks for the suggestion.

As a general update, the mower developed a couple of other (non-engine) issues and is being retired. I'm currently looking at options for getting the engine re-purposed by A.N.Other.
 
Anyone thought of that it could the plastic choke shaft binding up? From either gumming up or plastic swelling.
 
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