Cub Cadet 125 running issues w/ video
 

Okay, someone please help point me in the right direction. The points and condensor are brand new and have been adjusted and readjusted a dozen times. I'm very confident that's not what's causing this.

It seems to me that the engine is running very hot, and just shuts down under load. Then doesn't want to start again until it cools for a bit. It will sit and idle fine for an hour or more, but once you put it under load (drive uphill, engage blades for more than a few minutes, etc.), it will die, backfire, then won't start.

When trying to restart, it will throw flames out the exhaust, and backfires louder than a shotgun. Walk away for 10 minutes, come back, and it'll start right up.

Anyway, here's the video, any help is greatly appreciated.

http://i38.photobucket.com/albums/e1...ps53139899.jpg

Sticky exhaust valve

You're not the first person to say that, but my question is, how do I go about fixing that? I've used seafoam, marvel mystery oil, etc. Is there an easy way I can remove the valve to clean it, or clean it by just taking the cover off?

If you remove the cylinder head, and pushrod cover, the valve can be removed.

After watching your video..... I'm wondering if you cleaned the fuel system/carburetor? It sounds like it is running out of gas. I really think it starts back up to quick to be a valve. BTW, that is a gorgeous 125!!

yea good idea to go over the carb if you have not already, rebuild kits are under 10 bucks online

How much is your tractor charging? It looks like it is off the scale in a couple of places. I am wondering if the generator is dragging down the motor. On my 127, it charges up about halfway on the meter then goes to zero after a bit. If it is charging too much, the generator can bring the engine to its knees.

This is why I tried getting the gauge in the picture. The needle seems to peg all the way to the right at all times when the motor is running.

Yeah, I'm going to order a head gasket and a carb kit, I already got the tractor apart, and adjusted the valves to spec, looks like the head gasket is in bad shape, so I'll need to order one anyway. And thanks for the compliment, I got it on a trade and it's one of the cleanest ones I've seen around here. Really wish I could find a cheap semi-clean Original, or any gear driven Cub for that matter. Not a big fan of the hydro tractors....

Oh, and while I have the motor apart, any ideas on how to clean the valves without having to remove them? The exhaust valve doesn't seem to stick when rotating the motor by hand, but it does have quite a bit of gunk built up on the bottom side of it..

Thanks for the help guys.

Check to see if the generator is bringing the engine to its n]knees by starting the engine, then take the field wire off the generator while it is running. If the engine works fine, then you need to look into the voltage regulator or your wiring harness.

Darn, I wish I would've tried that first before I took everything else apart. Thanks for the suggestion, if all of this stuff doesn't resolve it, that will be my next thing to try.

I'm about 99% sure that it is not a voltage issue. I have never seen a generator pull a motor do a dead stop form wide open throttle. You may have a charging issue, but that is not the reason your engine is dying.

Do I need to replace the valve cover gaskets as well? I've torn them slightly taking the cover off, but I wasn't sure if they need to be 100% perfect or not.

I've already ordered a head gasket and carb kit.

yes you should replace the gasket

Well guys, I appreciate all the help, as I finally got this tractor running good. I pulled the head, cleaned the carbon, replaced the head gasket, adjusted the valve lash, and rebuilt the carb. Starts up on one crank now, and runs much cooler than before. I can mow with it, up and down hills even. And I can turn it off, and start it right back up with absolutely no issues.

Thanks again for all the help and advice. I appreciate it.:beerchug::beerchug:

That's great news! :beerchug:

X2!:beerchug:

Here she is after mowing my entire lawn, without a single issue. Not even a hiccup. Thanks for the help guys...

http://i38.photobucket.com/albums/e1...psbcf186cd.jpg
http://i38.photobucket.com/albums/e1...ps91cbc5f3.jpg
http://i38.photobucket.com/albums/e1...ps2a1a95e8.jpg

Very nice tractor. You did a good job getting it running good.
Kind of makes me want to get the 125 in the shop. It needs everything!
Regards,
Chris

very nice! looks almost new man!

Nice 125, you have there!