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All-Terrain Lawn Tractor Forum :: Technical Forum :: Engine Tech :: General Engine Tech
 

 Backfires when brought to low idle

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willis923
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kieranruffell
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Backfires when brought to low idle Empty
PostSubject: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 26th 2014, 4:21 pm
My kohler 12.5hp backfires when throttled down to low idle.
Any suggestions on how to fix this.
Thanks
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willis923
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Backfires when brought to low idle Empty
PostSubject: Re: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 26th 2014, 4:35 pm
does it backfire while its coming down? or while its idling?
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TroyBilt Pony
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Backfires when brought to low idle Empty
PostSubject: Re: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 26th 2014, 4:40 pm
Valve lash? Cam timing? Slightly sheared flywheel key... could all be to blame..
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Lawren Wimberly
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Backfires when brought to low idle Empty
PostSubject: Re: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 26th 2014, 4:50 pm
probably not enough lash in the intake valve. The plug actually fires on the exhaust stroke too... if there is sufficient fuel still in the exhaust, it will fire out of turn
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kieranruffell
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Backfires when brought to low idle Empty
PostSubject: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 26th 2014, 5:08 pm
Thanks for the suggestions
just to clarify it backfires when being brought down not at idle
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willis923
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Backfires when brought to low idle Empty
PostSubject: Re: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 26th 2014, 5:22 pm
mine used to do that when it was too lean
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PostSubject: Re: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 26th 2014, 7:28 pm
First place I'd look is the mixture, may well be on the lean side. I've had engines do this after instaling a free-flow exhaust system, before I'd had the chance to adjust the mixture to suit.


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T-Dub13
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Backfires when brought to low idle Empty
PostSubject: Re: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitimeJanuary 27th 2014, 2:45 pm
Lean. Most likely the carb like most are saying. The other major cause of backfiring is an exhaust leak. Air getting inside the exhaust system then you let off of the throttle. Is your exhaust tight and not leaking?
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kieranruffell
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Backfires when brought to low idle Empty
PostSubject: Exhaust   Backfires when brought to low idle Icon_minitimeJanuary 27th 2014, 3:03 pm
I have recently replaced both bolts and the exhaust gasket.
I am pretty sure there are no holes in the exhaust and the bolts are tight.
Thanks for the tips.  Very Happy


Last edited by kieranruffell on January 27th 2014, 3:07 pm; edited 1 time in total
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kieranruffell
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Backfires when brought to low idle Empty
PostSubject: Carb   Backfires when brought to low idle Icon_minitimeJanuary 27th 2014, 3:05 pm
Last night i cleaned the carb
just need to find time to put it back on and readjust it. Hopefully it makes a difference.
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Backfires when brought to low idle Empty
PostSubject: Re: Backfires when brought to low idle   Backfires when brought to low idle Icon_minitime
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