"The Rat" 12.5 HP Kohler swaped Huskee 4200 LT MTD

well see this engine has a mechanical fuel pump and it is trashed and the steal fuel lines from the pump to the carb ar trashed too so right now it is just gravaty fed and this carb is for a pump fed engine so it probaly isnt geting enough fuel

Murraymountain wrote:

That could be the case, but I’ve been dealing with similar issue with my Kohler swapped Murray LT. I put 2 brand newish carbs on it and it did the same thing. Would fall flat on its face if you tried to up the throttle at a normal pace. Just couldn’t get it dialed in for anything. Went to the junkyard and found an original Kohler carb and threw that on it and now it runs perfectly! So I’m betting on the carb cause these new cheap Kohler ones always seem to have a problem.

That’s my just my experience with them + an extra 2 cents.

You should run the experiment with one of the carbs that ran crappy, get a pin vise and open up the main jet a little and test, open the pilot (if possible) and test. Open them up a little at a time and I bet you'll see improvement, I've done it successfully! Any time you imporve airflow with an intake and or exhaust you'll need to fatten up the jetting a little, especially with newer built carbs that were EPA approved and run on the lean side.

Fastman wrote:

well see this engine has a mechanical fuel pump and it is trashed and the steal fuel lines from the pump to the carb ar trashed too so right now it is just gravaty fed and this carb is for a pump fed engine so it probaly isnt geting enough fuel

Diaphragm and spring kits are available for the Kohlers for under $20 but the 4 holes need to be elongated towards the center by about a 1/8" each if you have a old school aluminum pump. I think the diaphragm kits were designed for the new, plastic replacement pumps but I've never been able to confirm that physically, I did rebuild an old aluminum one though.

Finaly got to drive it with the big pulley on it (I had to put the original engine pulley on it at first cause I didn't have a belt small enough) and after driving for about 15 minutes it blew up the brand new uper drive belt that I had just got this morning, so when I buy a new one imma buy a "high power" one from O'Reilly

It also did about 26 mph with the factory sized back tires

Should be getting a new belt in for The Rat today and imma do a top speed run, I turned it up quite a bit the other day I'll tell yall how the run goes

The test yesterday went horrible it killed the brand new belt yet again so as soon as I figure out how I am getting rid of the varidrive i am complete open to suggestions

You could replace it with a jackshaft. Question is what destroyed the belt? Mine works fine and doesn't chew belts.

I’d put one of these on the PTO and use that like a cvt. Should work fine.

Brianator wrote:

You could replace it with a jackshaft. Question is what destroyed the belt? Mine works fine and doesn't chew belts.

I honestly have no idea

The engine to this rig is now in my new workhorse (1993 john deere) it will be getting the same style engine in the future but with electric start