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Old 07-31-2014, 03:32 AM
Haake Haake is offline
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Snapper backfires Please help

I have a snapper riding mower and after it runs for a while it starts backfiring and smells burnt... Any help would be appriciated.
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Old 07-31-2014, 09:56 AM
OptsyEagle OptsyEagle is offline
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Will need an engine brand and model number.
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Old 07-31-2014, 10:09 AM
hal hal is offline
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How old is it? When was the last time of tune-up? Could be as easy as spark plug fouling, or ignition module over heating, plugged gas cap, dirty air filter, broken plug wire, rings,........ Try some of these first. Fresh gas?
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Old 07-31-2014, 07:43 PM
Haake Haake is offline
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Quote:
Originally Posted by hal View Post
How old is it? When was the last time of tune-up? Could be as easy as spark plug fouling, or ignition module over heating, plugged gas cap, dirty air filter, broken plug wire, rings,........ Try some of these first. Fresh gas?
Would adjusting the idle throttle have anything to do with it? Or the needle valve? Its over 15 years old btw
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Old 07-31-2014, 07:44 PM
Haake Haake is offline
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Quote:
Originally Posted by OptsyEagle View Post
Will need an engine brand and model number.
Briggs and Stratton
252707-0208
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Old 07-31-2014, 08:33 PM
OptsyEagle OptsyEagle is offline
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Most backfires are fuel igniting inside the exhaust cavity. Perhaps your exhaust valve is not closing enough allowing fuel to enter the exhaust and ignite. I would try to get a look at the valve clearance. Your exhaust valve should have a clearance between 0.009" and 0.011". If the clearance is too low or there is no clearance at all, it can prevent the exhaust valve from properly closing.
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Old 07-31-2014, 08:36 PM
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Patriot Services Patriot Services is online now
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Exhaust valve is hanging after heat expansion. Either the lash is closing or its hanging up and not seating.
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Old 08-01-2014, 10:29 AM
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JimQ JimQ is offline
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Sounds like valve issues but also check the throttle shaft for excessive clearance. They wear, suck air, and cause the engine to run lean.
Q
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