Kohler 15hp Backfiring

[MBTRAC]

Hi seeking ideas on how to fix a Kohler 15hp which is backfiring - it's just commenced backfiring , only occurs when the engine is warm at idle/standby revs after throttling down.
Everthing else on the engine is fine & it runs apart from the backfiring faultlessly (i.e no oil usage, no leaks, no "rattles" & it remains easy to start), regularly maintained & always run on "fresh" 95 or 98 non ethanol fuel - currently @ c.420+hrs ( originally out of a JD LT155 wreck with unknown hours & has done 420hrs driving a water pump for me).
Thanks

 

[Rivets]

Please post the model numbers.

 

[MBTRAC]

It's a Kohler Command 15QT/CV15S-41562 single cyl 15hp
Thanks

 

[Rivets]

Kohler Engines: Owners and Service Manuals: Manuals and Maintenance

Free Kohler Service Manual Downloads : Kohler Engines and Kohler Engine Parts Store, Genuine Kohler Engine Parts

At one of these websites you should be able to download a service manual for your engine. They have good troubleshooting charts and will be a good start for you. If they don't help or you have any more questions post back.

 

[EngineMan]

Backfiring (and misfiring in general) can be caused by a large number of problems, just a few.....
valve timing
valve clearance
ignition timing
It is unlikely that the problem is due to carburettor malfunction: however, check that the carb float are OK if everything else seems fine. I presume that by inspecting the spark plugs you concluded that the carb air/fuel mixture was basically correct.
A leak in the intake system can cause backfiring intake manifold gasket and exhaust gasket
and is the back fireing coming out of exhaust or carburettor, if carburettor it could be a weak mixture

 

[MBTRAC]

Thanks Rivets for the links, I'll download the manuals & see what I can fathom out - usually can figure out a fix but this engine has me beat at the moment.

Engineman- appreciate your input - the backfiring is coming from the exhaust - already checked the carby (it's ok), inspected the orginal plug it was without any of the "tell tale" signs, & replaced the plug anyway to no avail - my next port of call will be the ignition........as you say it can be any of a number of things so I'll keep searching.........Thanks again.