Got a 125 with engine questions

[Sbull81]

I just picked up my first Cub. It's a 125. The K301 is smoking a bit while using it. Starts super easy and has great power still. But I'm wondering if I should rebuild the K301 or repower it with a 14 or 16hp. Is that even an option without cutting it up. The tractor is very nice.

[mortten]

14 or 16 won't fit without doing some cutting. You can fit a 14 in by using the blower housing, flywheel, and bearing plate off of a 12. Nice looking tractor. I'd rebuild the 12.

[olds45512]

I'd rebuild the 12, I've never ran out of power with a good running k301.

[sawdustdad]

Another vote to rebuild the 12. The ONLY time you'll wish you had more power is with a 48 inch mower in grass you let grow too long. And even then, with a 14 or a 16, you'll still wish you had more ummph. So the 12 is a great workhorse. I use a 48 inch deck on my 108 that has a 12hp/K301 in it now. Plenty of power.

[J-Mech]

You don't mention how much oil it is going through..? Is it black smoke? Or oil smoke? If it's not going through a bunch of oil, I'd leave it alone.

If you do rebuild, you'll be happy with the 12HP. I push things harder than most... I've ran a 50C deck on a 10 HP tractor for at least one, maybe two seasons. Finally got a 44 and put on it. Still pulls it fine. The 50" was a little much in heavy grass.


You can do the 14/16 set up for a NF, but lets just go with you need to know how to set it up so it doesn't run hot. Plus, they are hard to get running right with the lighter flywheel. Stick with the 12.

[Jeff in Pa]

First, welcome to OCC

I highly recommend rebuilding the 12 hp. Both my 125s work just fine with 12 hp.

Jeff

[cadzag72]

That's a nicely set-up 125! Agreed, fix up the 12, you'll be happy for decades. My 72 had a 12hp transplant sometime in the 1970's and is still chugging along without missing a beat.

[Cub Cadet 123]

I would run some Marvel Mystery Oil in the oil briefly and in the gasoline, as well as check my carb settings. Then, change out the oil to pure synthetic. The Marvel Mystery Oil will clean things up a bit if you have a stuck ring and the synthetic oil will not smoke. In the gasoline, it will help to clean up and lubricate the upper chamber of the engine. As J-Mech said, you did not describe your smoke, so you may have incorrect settings on your carb causing it to burn excess fuel and as a result, smoke. So, you may not need to rebuild the engine after all!

You do have a fine looking 125 there.

Cub Cadet 123

[Merk]

I purchase an IH Cub Cadet 128 last fall that the owner said hasn't run in 4 years and smoke when he last ran it. While I had the carb off to rebuild it I remove the breather cover and decided to check the valves. I found a piece of dirt in the drain back hole. The 128 hasn't smoke or used any oil in the 5 hours that it was ran. The 128 has a #2 tiller and will get a good workout this spring.

I add Marvel Mystery Oil to my storage fuel containers.

[Sbull81]

Haven't had much sunny weather to be able to see if the smoke is blue or black. I know the previous owner replaced the carb with a new one. Perhaps it is running rich. He said he would have to add about 3 oz of oil every 10 hours of use or so