Kohler K301 engine breaks up

[Erich]

Hi, I'm new to the group and I hope one of you can help me with my Cub Cadet 127 with a Kohler K301 engine.

It was running fine this winter and I did some good snow plowing with it. Early in the spring, while starting up, she backfired once and then wouldn't start easily. Wen it did, it wouldn't rev up and kept breaking up and backfiring and had no power under load.

I thought it was an ignition problem and so replaced everything in the ignition sytem, one item at a time, with no help. I replaced the plug, the coil, the points and condenser, bypassed the switch and put in a new wiring harness.

A local dealer told me it might be a valve problem, so I tore off the head and sure enough, she had a fairly pitted exhaust valve, which I was able to reseat. I also checked for a sheared flywheel key, as long as I was tearing into it, and after breaking two shroud bolts, found the key was intact. Unfortunately, when I started it up, it had the same symtoms.

I find I can get it to run a bit better if I open the point gap way wide. It runs a bit smoother, right up until the spark quits entirely, but it never gets to the point where it has real power at high RPMs and it still will backfire occasionally at high RPM with no load. As soon as I put a load on it, it sputters and dies. Also, when shutting it off, it backfires through the muffler after the engine has stopped. I had to replace one muffler already because of this.

I also checked for fuel flow and it seems fine, although doesn't make sense to me that it would be a fuel problem since it does run somewhat better and faster when I change the spark timing.

I'm at my wits end and I've already invested well over $200 and a lot of time trying to find the problem. I hate to have to throw away such a nicely built, cast iron, ball bearing engine to replace it with something that will be expensive and probably less robust than what I have, but I don't know what else to do at this point. Can anyone here offer me a clue?

Thank you,

[Fill]

OK...that attachment apparently didn't work the way I wanted it to. Darn computers. Try this, go to- Links - Cub Cadet Related Links - scrolldown to- Cub Cadet Frequently Asked Questions - Question #1

[Erich]

I apologize for my ignorance Fill, but I don't see 'links'. All I see is quick links and there are no other headings to match what you said under that.

[Yosemite Sam]

First off, (please understand that I'm not beating up on you or anything, I just hate to see someone spend a ton of time doing something that isn't at all related to the problem) unless you are timing the engine with a timing light, the position of the flywheel doesn't have anything to do with the ignition timing, so a sheared flywheel key is of no consiquence.

The problem could be electrical, but from the description you gave, I'm not totally convinced. If you think that it is then, first thing, with a test light, check your grounds (might sound silly to you, but go back through all the posts on this sight and you will find that more often than not a bad ground is the problem, if an engine isn't running right) connect your test light to the pos. battery terminal and start touching everything that is supposed to be grounded (including your coil) then go the other way hook to the neg. battery terminal and start touching everything that should be hot.

If you don't find any problems there, then you may want to try checking your carb. First thing check to make sure there isn't too much play in the throttle shaft if air gets sucked through there you will NEVER get it adjusted right and it will never run right. Take the high speed mixture screw out and check the end to make sure it isn't bent, then clean out the tiny little holes in the needle, two high and two low, make sure the center of the needle is clear also (the area between the two sets of holes). Put it back in, turn it to closed and then turn it out 2 (two) full turns, then turn the idle mixture screw in all the way and then turn it out 1 and a quarter turns (1 1/4). If the engine misses and backfires, turn the high speed mixture screw "out" 1/4 turn at a time until the condition is corrected. If the engine is sluggish under a load and has black sooty exhaust, then turn the high speed mixture screw "in" 1/4 turn at a time until the condition is corrected.

[artieb]

Originally Posted by Fill

OK...that attachment apparently didn't work the way I wanted it to. Darn computers. Try this, go to- Links - Cub Cadet Related Links - scrolldown to- Cub Cadet Frequently Asked Questions - Question #1

Originally Posted by Erich

I apologize for my ignorance Fill, but I don't see 'links'. All I see is quick links and there are no other headings to match what you said under that.

Here's the page he was trying to direct you to:

http://cubfaq.com/questions.html

[Merk]

Same fuel from winter to spring?
Do you use a fuel stablizer?
What brand if you do?
What brand sparkplug?
When was the last time the air filter was clean and change?

It sounds like a fuel related problem to me. First thing I would is check the throttle shaft as Yosemite Sam suggested. Along with the throttle shaft I would rebuild the carb. Odds are there is dirt inside the carb.

[Erich]

Thanks for getting back to me guys.

Merk,

I've been using the same brand of fuel - Mobil regular - but the fuel I burned in the Winter is all used up and I put in fresh fuel last week. I don't use stabilizer, should I? I'm not sure what the brand of plug is, but I got it from the local Kohler engine dealer. He told me the plug and all the electrical components I bought were either genuine Kohler parts or Kohler recommended. I changed the air filter when I started having the problem. There was no change in performance, and no change between having the filter on or off.

Fill and Artieb,

I didn't see any carbon buildup of the sort shown in the picture under the first faq. There was a slight amount, but nothing like what was shown. The exhaust valve was pitted, but no so much that I couldn't reseat it. The engine still backfires after rdoing the valve job and emoving the small amuont of carbon that was there.

Yesemite Sam,

I will run the electrical tests in the morning and do the carb cleanout. I did open it up to see if there was anything egregious stuck in the jets, but I will check it again and especially the throttle shaft clearance. I realized I had been pissing up a rope on the flywheel after the fact, when it dawned on me that it was a coil ignition system. I checked the key because the guy at the local Kohler place suggested that a sheared key could possibly be the problem. Evidently, he forgot it was coil ignition too. Although he did suggest I use the flywheel to set the timing, so maybe that's what he was talking about. Oh well, I wanted to learn as much as possible about the engine anyway. I have high hopes that one of your suggestions will do the trick. I'll keep you posted.

Thank you all for your input. I at least have some leads, when before all I could do was scratch my head.

[Matt G.]

Did you reset the valve lash after grinding the valve?

[Erich]

Hi Matt,

Yeah, I got the specs from the Kohler guy. I think it was .0045 and .0075 - something like that.

Thank you.

[Matt G.]

Originally Posted by Erich

Hi Matt,

Yeah, I got the specs from the Kohler guy. I think it was .0045 and .0075 - something like that.

Thank you.

If that's what you set it to, that's WAY too tight. Exhaust valve is .015" to .017".