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Adjustment screw on Walbro LMT...

9431 Views 2 Replies 2 Participants Last post by  Poodlehead

I've got a Snapper 301318BE rear engine rider with a Walbro LMT carb. The carb only has one adjusting screw that points diagonal toward the intake path. What is this screw for?

The reason I ask is because it has to be adjusted about 3 turns out to run fairly smooth. It seems to effect low and high speed running. Most adjustments are ~ 1.5 turns so I'm wondering what/if this is masking some other problem.

The Motor Model/Type/Code are: 28M707/1166-E1/125ZE

Thank you!
1 - 3 of 3 Posts
I would guess it's for idle mixture. If that is the case maybe backing it out that far is compensating for a partly plugged main jet. Just a guess but sounds like something might be getting plugged somewhere especially if it still does not run all that great with that screw backed out.

You can get a manual here if you need one:

Manuals | Customer Support | Briggs & Stratton

Unfortunately it does not show carb adjustments (what little can be made) in it. :(
It actually does run pretty good backed that far out, but I know there has to be a reason for it. I know when I cleaned the carb a year or two ago, the bottom of the bowl was a bit rusted. I cleaned it good, but maybe a chunk came off since. I think I'll pull the carb one more time and spray/blow through the passages again and put a new bowl on it.

First, a new air filter and plug. I doubt that will make a difference, but those haven't been replaced since I got this mower from 'a butcher', so it can't hurt.

Thanks for the info and link!
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