Mower has low power after tune-up

[mjw357]

I have an Exmark zero-turn with Kawasaki FX801V engine. Brought it in the garage last fall, all was running perfectly. This winter I changed the oil and filter, fuel filter and the rocker cover gaskets because they were leaking a bit. While I had those off I figured I would check/set the valve clearance.
Went to mow this afternoon, started right up and let warm for a couple minutes before I started.
Wheeled over to the yard, half throttle, turned on PTO to start blades, full throttle. Seemed OK for a few seconds then lost power when I started moving. It just is not making full power/RPM’s with mower engaged.
What’s everyones first thought?

 

[BillC72]

Valve lash not correct. Getting too tight as temp oncreases. Just a guess...

 

[5030]

Valve lash not correct. Getting too tight as temp oncreases. Just a guess...

Good guess. All the vertical V twins, Kowalski, Kohler and Briggs are all touchy with valve adjustments and they have to be right on or they run like crap.

 

[mjw357]

So got it back running. Here’s what happened.

Apparently did not fully tighten locknut on one of the rocker adjusters. No damage, all parts found. Set valve clearance to 0.004”-0.005”, reassembled and ran.
Mowed for a couple minutes then died, like turning the key off. Restarted using choke even though it was warm. Surged and died a couple more times under load. Ran it back to garage with mower off surging the whole way. Took carburetor off and opened float bowl.

Debris in opening opposite needle valve. Cleaned carb out and reassembled. Wife mowed with it for over an hour, all good.