Small Engines (Lawn Mowers, etc.): kohler engine lacks power, kohler k-series

Question
QUESTION: I have a case tractor with a cast iron Kohler engine.  It's probably 17 hp+/-.  The engine starts fine and runs smoothly, but bogs down and quits when under a load.  It also backfires loudly through the exhaust on shutdown.  I have cleaned the carburetor, installed a new fuel filter, changed the plug, adjusted the carburetor following the maunal, checked and gapped the points.  Any ideas?  Someone suggested that the timing may be off, but i don't know where to adjust or check this.

ANSWER: It sounds like you may have a valve that's sticking or not seating properly.  Have you had the head off?  It's normal maintenance on the old K-series, (I'm assuming that's what this is?) engines to pull the head and clean the top of the piston and combustion chamber.  While doing this you can get a good look at the valve motion and seat condition.

If you brought this into my shop I would probably do a leakdown test.  I wouldn't be surprised to find the exhaust valve needing to be lapped or re-seated.

Explaining the timing procedure on the K-series is best left to the service manual.  It would be worth checking as it could also cause your problem.  The following link is to a site where you can download a copy of the manual you need.  There are 3 different ignition systems used, so be sure to follow the right directions.

http://www.asberry.net/Kohler.htm

Usually when you hear of low power AND backfiring through the exhaust at shutdown, you suspect the carb.  The backfiring is usually caused by fuel loading up and being ignited by the exhaust.  This can literally blow a muffler apart.  If your spark plug is black and building up with carbon, then you have a carburetor that's too rich.  Also it there's any black smoke or black deposits on the exhaust, you're running rich.  

Is your tractor a Case/Ingersoll?  I've been wanting one of those myself.


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QUESTION: yES ITS A CASE/INGERSOLL 222.
Is there a re-build kit for the carb or is it necessary?
When I cleaned it, I took it apart and blew out all of the ports that I could find with compressed air.
Is there a better method?

ANSWER: There ahould be a kit available.  If you can give me the numbers off the engine I can look it up for you or you can look it up in the Kohler list on my site.
http://www.grandjunctionsmallengines.com/pages/parts/viewbybrand/default.aspx

To properly clean the carb, you should disassemble and soak in carb cleaner for an hour or more and chase all the holes with a fine piece of wire.  The carb vats they sell at most auto parts stores work very well.  They come in a can like a paint can and usually have a basket for parts inside.

That little tractor you have is an outstanding machine and well worth spending money on.  It's much more durable than most of the lawn tractors you can buy today.  It's also highly desired by collectors.

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QUESTION: I will get the engine model and serial.  If I want to take off the head and clean the parts, will this require a new head gasket? and what sealer is good?, and what pressure should the bolts be torqured on the re-assembly?

Also, I have noticed that the fuel filter is sometimes half-full and sometimes almost empty, but never solid with fuel.  If this is not normal, I am thinking of a leak in the fuel line or a weak fuel pump.

The suggestions you have given so far have been very helpful, but I have not had the time to try them.

Answer
The filter probably won't ever fill up, as long as fuel is flowing through it, you should be okay.  Now if the fuel supply gets so weak that the engine is skipping, that's a different story.

It's recommended to replace the head gasket, but we don't.  On an older engine that's never had the head off, I would replace the head gasket.  

There is a proper torque pattern, a proper torque and a proper method for torquing.  That's all in the manual and dependant on just which engine this is.

Thanks, PK.