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persof

backfiring upon shutdown

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persof

I have a C161-a that backfires when I close the throttle and when I turn the key to off. This is quite anoying, any way to fix this?

Thanks

Francis

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nylyon

I haven't found a solution, but have 2 work arounds. Let it idle for several minutes then turn off the key, or turn it off at about half throttle. Quite annoying and can't be good for the muffler.

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AMC RULES

...or the head gasket either.

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rmaynard

Sounds like you may have the carburetor set too lean, or you may have a bad exhaust valve.

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roscoemi

I had this issue on my C-121 that was running on the rich side. A new condensor fixed it.

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JackC

The carburetor setting could be the culprit. When I had that problem, I cleaned the carburetor and set the needles according to the manual and the problem went away.

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midnight rambler

i agree letting it idle a minute or two just to let it burn the fuel in the cylinder(16hp has a big bore to completely burn all the fuel) or you can just get ready look at the neighbors and smile.

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corn53

My k341 also has this issue. Good question!!!! :handgestures-thumbupright:

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meadowfield

my carb was full of crud causing this - temporary fix was to rev hard (past the governor) blocking the air intake (making it backfire more) :hide: but afterwards it was sweet.

I did however shortly after do a full carb rebuild and new plug....

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Wheel-N-It

99 percent chance its your carb out of adjustment. Clean the bowl, install a new spark plug and air filter. Set the carb low speed and high speed adjustment screws to the prescribed factory settings. Start the engine and see what happens. If you still have the same problem then make the necessary adjustments beginning with the low speed adjustment screw, then the high speed adjustment screw.

Until you get the problem completely solved, I suggest you have the idle set low, and as you turn off the key switch, engage the pto. In other words put a load on the engine to slow it down quickly as it is turned off.

One other tip before you make adjustments; Spray some BrakeCleaner into the throttle shaft area to loosen any deposits there or downstream from there. Spray at the top of the carb where the throttle shaft comes through the top of the carb. You want the brakecleaner to pass between the throttle shaft and the throttle shaft bushing. I know this sounds crazy but try it. You should do this about a dozen times. Give it a good spray till the motor starts shutting down then stop spraying till the RPMs pick back up, then repeat.

WEAR SAFETY GLASSES WHILE USING BRAKECLEANER!!!.

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Buckshot 1

:eusa-think: I not sure you should use brake cleaner, as it is highly toxic when when it is sprayed around/into any heat source. I always idled mind down for a short time and turn it off. :flags-usa:

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SousaKerry

When is the last time you had the head off? Cleaning out the carbon deposits can do wonders for these type of problems. I have seen a couple of articles or posts about this that the carbon deposits will glow red hot after the ignition is killed and cause the unburnt fuel to ignite. In severe cases it can cause the engine to keep running after shutdown.

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