Kawasaki FH680V Surging & Running Rich
This one has me stumped.
New-to-me mower (Cub Cadet Commercial Tank) with a 23 hp Kawasaki FH680V-BS18, 270 hours
I had a hot start problem, repaired a chafed stator wire, disassembled & cleaned the carb & installed new gaskets, and set the valve lash to 0.004. The hot start problem went away, but now...
At idle, it searches/surges around the set 3600 rpm idle speed
When I engage the blades, it doesn't even want to come up to speed
If it does come up to speed and I try to mow up even a slight hill, it bogs down severely.
Then I realized that it's running incredibly rich! I can't even bear the fumes from this thing when it's running in my shop with the doors open (and I thought my Corvette ran rich at idle!!)
Running at part throttle, it goes like this:
1) rpms drop
2) backfire out exhaust when the rpms bottom out
3) rpms come back up
So somehow, this thing is running incredibly rich, and I now think that's the root of the problem. How does that happen in an engine as incredibly simple as this thing? The carb has a couple jets, no mixture screws, a float and that's about it. I had the carb out, cleaned everything, blew out everything with air, and reassembled with all new gaskets.
This HAS TO be something simple.... UGH!
Thanks in advance for any help!