Cub Cadet 108 troubles.

Recently my Cub 108, old Faithful, wouldn't start. I gave it a thorough going over, including points, condenser, coil, and carb rebuild. Started right up, and ran smoothly, after a little carb adjustment. Drove it about for awhile, when it started to cut out, and backfire. Back in the garage it went. Thinking it was dirt in the tank, I took it off and cleaned it. Pulled the carb off, and checked it. It was fine. Pulled the head, off, valve seats, valves, cylinder walls and rings all looked good. Replaced the head, with a new gasket, a torqued it according to specs. After all this, the tractor starts right up, and idles, but carries on and backfires when you give it throttle. Opening the point gap all the way made it slightly better, but still is not right. What did I miss? Any input would be appreciated! Thanks for your time! (This has a Kohler 241.)

You didn't mention the spark plug. Is it a Champion? If so, try a new plug in a different brand. Then check the condenser. Many new ones are defective. This sounds like you have a heat failure somewhere in the ignition system.

Do you have a known-good coil you can substitute? Also try another known-good condenser. It is not unheard of to get a bad one of either part.

If all the other suggestions fail, try replacing the wire between the coil and points. I have seen two Kohlers where the wire shorts at the metal clips it is routed through. (You can sometimes see the tiny spark at that clip at night in dim light.)

gravelynut:

Did rebuild and adjust the Carb to the Spec's in the Kohler Service Manual ???

Try putting the old condenser back on. Lots of reports of the new ones being bad. And the improvement with point adjustment makes me think it is ignition, not fuel related.

Ah not being a real expert on Cubby's JUST YET . I just bought a 1250 NON running and the guy i bought it off of told me it was running fine then just quiet and never started again, He thought it needed points ,NOPE the problem was ING switch and the connector an two delco 56 wire terminals ,. I checked the inernet for a ing . switch and had heart failure then went to the OLD Case I H store and saved myself 24 bucks and even got the five hole plastic wire connector that ion the internet was 7.49 , it was a BUCK there . Put the new switch in with the new wire ends and she fired up and ran like new . Check your ing. switch for corrosion and bad contact . as the parts guy at the Case I H store said a common problem .

Good morning, all: I had a training course on electronics in the military. One concept they emphasized was that wherever you have had your hands on a circuit, that is where you may have a problem. This applies to all troubleshooting. The more parts you change out, the more problems you may have. If you swap out a part with another one, how do you know the replacement is a good one??? Just me thinking...
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Dennis M. in W. Tenn.
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I agree that it sounds like ignition, but I am definitely not a fan of ethanol gas in small engines

JERRY WOW, I MUST BE DOING SOMETHING WRONG, Every Champion plug I buy works fine. I did have a clapped-out K161 or 181 in the old Cub Cadet 70 Dad bought new in 1965 and we rebuilt or replaced the engine 3 times plus the engine that was in it when Dad gave the tractor to me, think it's Wheel Horse tins on it. I was doing grading with it with my home-made belly blade, lots of low speed idling, fouled a Champion J8 out, NOT the fault of the plugs, bought a couple NGK plugs, finished my grading, fouled the NGK plugs too. I rebuilt a K241 10 hp and installed it in the 70, also have an H10C in my K321 14 hp Kohler in my #72, and in my B48G ONAN in my 982 Cub Cadet, it does have the points or condensor go bad about every 20-25 engine hours. I use Champion plugs in my two FARMALL tractors , a '51 M with M&W sleeves & pistons, and my '54 Super H that I push snow all winter with that's never been overhauled, cranking compression pressure is low, 105-110 psi, should be 125+.
Most of the Champion plug problems are either bad ethanol gas, or bad cheap plug wires.

Try this:

The initial setting for points on those engines is .020 and
is measured when the points are fully open. The points close
to create the spark. This will get your timing close enough
for most practical purposes.

Once you get the engine starting and running well, you can
try and fine-tune the timing with a timing light or otherwise.

I don't want to hijack a thread with a spark plug debate, but spark plugs are a funny animal. What one person swears by, the next guy swears at. My old Arctic Cat snowmobile hated anything but NGK. Champion, AC, Bosch, Autolite...I had to change them about every time I wanted to ride. NGK would last quite a while. A friend had a later 70s chevy pickup that ran great on Champions but fouled out AC. The brand of cars I am a tech for came from the factory with Champions in the early 2000s, but they put out a service bulletin saying to change to NGK and don't use Champion anymore because we were having a lot of misfire issues that seemed to be resolved with the NGK plugs. Most of my small engines seem to prefer Champion. I worked for an old Chrysler mechanic who had his own shop. He always said to use only Champion in Chryslers, AC in GM and Motorcraft in Fords. Use NGK in Imports. And for the most part, this has worked for me. In my Farmalls, I haven't really noticed much difference between brands.

Dad sold a real nice '53 Super M to a young farmer, first thing the young guy did was go to Farm & Fleet and buy everything to do a tune-up. He replaced the Lord only knows how old D-16 Champion plugs with AC, used the off-brand points & condensor to replace the still fine stuff on the tractor, day or two later the young guy calls Dad complaining the SM won't start. Dad grabs his Doctor's Bag has all his tune-up tools and goes to look at the SM. New plugs, wires, points & condensor, plastic fuel filter installed. Dad drives the 3-4 miles to the IH dealer, gets a second set of all OEM parts and heads back to work on the SM.
Dad just gets the SM started and idling to warm up, young guy shows up, Dad hands him his mess of cheap imported tune-up parts plus the invoice for $40-$50 worth of IH OEM parts telling the young guy He'll take cash or a check since his check for the tractor was good.
It's too bad the IH plants that made the IH ignition parts and carb parts are now Shopping malls or car dealer lots, hard telling where Delco makes stuff now days.
I'm really fussy about what I put in my equipment for parts. I bought new old stock IH Fire-Crater sleeves & pistons/rings for my Super H for almost as much as Dad paid for it in 1968 when he bought it.I had 30 years experience buying mostly metal parts for manufacturing, cheap imported stuff us mostly crap.

Agree. Most of my tractors have ignition parts that are 30 or 40 years old and are still working fine. The last one I put anything in was an M about 20 years ago and for that I used Standard Blue Streak parts because we stocked them where I worked and it's still running strong. I don't know if you can even get them anymore.