12hp kohler mystery problem

[12 hp Kohler 1,020]

The 12hp kohler k301s on my charger 12 has been running on and off for the past month now. Sometimes i will go to start it and it will fire right up and run great, then i will get it out and drive it around a little bit. while i am driving it it will randomly just cut out and stop running. After it cuts out it is almost imposible to get it to start again. Other times i will go to start it and i will have to crank it so long that it kills the battery. Sometimes when it starts it will do this half running sputtering miss firing thing and will sometimes fire up but other time stall out. So far i have rebuilt the crab and reset the carb screws, i have adjusted the points and put a new condenser in, and put a new spark plug in. The engine seems to have decent compression and good spark. I took the head off the other day and other than a lot of carbon build up it seemed okay but there did seem to be  more oil on the piston than usual, the head gasket looked wasn't leaking at all. 

Any Opinions or thoughts on what the problem might be ? 

Picks of Magneto and Carbon on piston.

 

[formariz 11,994]

Oil is definitely leaking past your rings hence not only the visible oil but also the "clean" part of piston. That I don't think will prevent it from running. Did you check for spark when it stalls and wont start back up?Did you check condition of points and condenser?

[Mike'sHorseBarn 3,133]

Sand your contacts on the magneto, coil, and flywheel. Check your points and condenser as well, if they haven't been checked in a while, I'd just go ahead and replace them just to be safe. I had this trouble on k91 that has the same type of setup and it ended up being the coil though.

[pacer 3,175]

I'm thinking a close check of the ignition switch in needed, they often get bad/corroded conex at the back of them. I've had 5-6 of them give me problems like you describe -- in fact, I have one now that sometimes I have to reach under the dash and 'jiggle' the conex (that one is on my "rountoit list!). More often its the battery pin where the plastic will be melted around it and the corrosion there, often going back to the amp guage.

[squonk 42,546]

How clean is the plug when it starts running bad? I had a k301 that didn't smoke but pushed so much oil and crap out it would foul out the plug in 5 minutes.

[12 hp Kohler 1,020]

Thanks for the info guys, I did forget to Say that is does foul the plug a lot and also sometimes puffs smoke. It may need rebuilt. 

[953 nut 57,921]

2 hours ago, 12 hp Kohler said:

Thanks for the info guys, I did forget to Say that is does foul the plug a lot and also sometimes puffs smoke. It may need rebuilt. 

Robbie, that shiny cylinder wall and oil wash on the piston do look like a little refresh is in order.

Prior to pulling it apart I would suggest cleaning up the points, flywheel and coil like Mike @Mike'sHorseBarn suggested so you know the condition of your ignition system.

[richmondred01 2,289]

Where there’s smoke there’s fire....that’s an ugly cylinder, piston and valves. I can see the piston gap. 

my guess is at minimum it needs to be bored and valves seats ground. I also suspect the crank will need to be ground. Do it once correctly and don’t look back.

 

Edited February 24, 2019 by richmondred01

[12 hp Kohler 1,020]

Over the weekend I cleaned up the carbon on the head and piston and around the valves. Also sanded the surfaces on the mag and the inside of the fly wheel. Put it back together and tried it out. It runs a little better now but still smokes like crazy when I throttle it up. Also has a lot of trouble starting and staying running on low idle. Looking like it needs a good rebuild. 

[Rob R 970]

The 301 is a great engine, the Kohler manual has the min and max stats many times the block and bore is good all that is needed is a good cleaning and honing (to restore cross hatching on the bore) along with a new piston and set of rings.