Briggs/Simplicity/Snapper Briggs OHV engine runs lean, governor set too low - Snowblower Forum : Snow Blower Forums
 
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post #1 of 4 Old 12-21-2019, 07:34 PM Thread Starter
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Briggs/Simplicity/Snapper Briggs OHV engine runs lean, governor set too low

Briggs OHV 205cc engine (120000) on Briggs snowblower (same model 922EXD for Simplicity and Snapper)

It was unused for two years; left with gas in the tank. I drained the tank, removed the carb and cleaned it clean enough to eat off it. No corrosion, just white gel deposits. High speed jet (bowl bolt) was clogged but is now open.





Problem is it that it runs lean and hunts when it is hot and the governed speed seems way too low throw snow.

It starts OK with full choke, but when hot has poor low speed or governed speed steady performance. At whatever the governed no-load speed is, it needs 3/4 closed choke to get it to run steady (obviously running lean). The governor is constantly (every second) pulling the throttle high to prevent it from dying. If I manually hold the throttle at say 1/2 or 2/3 full speed, the engine runs OK at those speeds.

The main jet has the number 75 engraved in it, which I assume is a 0.75mm orifice bore. The diameter of the wire I used to clean out the jet orifice was close to 0.75mm.

The idle passages might still be clogged, given the performance but the bore is plugged. I'd pull the plug but where does one get a replacement plug?


I'm reluctant to bore out the high speed jet since it runs OK at 1/2 throttle and higher. Does Briggs sell 80 or 85 main jets?

2. Can't find any manual Governor adjustment data in the Briggs shop manual

I downloaded the Briggs single cylinder OHV manual (typical minimalist manual) and the governor for a 120000 horz engine covers only throttle cable adjustment. There is no throttle cable on this snowblower, so there must be a manual adjustment somewhere (like there is on other models used for stationary service), but I can't find any type of adjustment that I could use to increase the governed speed high enough to get it to run steady.

The governor linkage at carb is as good as new, both link and the spring. And the way it hunts, the governor is doing its job, it's just set too low.


Anyone ever mess with the governor speed setting?
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post #2 of 4 Old 12-21-2019, 08:06 PM
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My opinion has it that: there's no reason to enlarge the orifice. I will assume you still have plugged passages which needs attention. As you said it sat 2 years and it was gummed up from age.
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post #3 of 4 Old 12-22-2019, 03:49 AM
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That white goo is from the plastic fuel tank. Briggs had a problem with them and had a certain recall on some of them because of the plastic the fuel tank was made from breaking down and causing the problem you have pictured.
That gunk clogs up the tiny passageways and jets in the carburetor plus the fuel lines and shut-off valves.
Briggs came out with new fuel tanks made from a different type of plastic and rubber parts because of the problem you just pictured. That was a couple of years ago, so check with a Briggs dealer to find out if your fuel tank is still covered by it.
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post #4 of 4 Old 12-29-2019, 11:55 PM Thread Starter
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all3939, You're right, the low/medium speed venturi orifices and one passageway were clogged. I started a new thread with photo summary for the benefit those who have low/medium speed issues. Dan
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