Cub RZT runs hard

[francis@mylegaltech.com]

My Cab Cadet Model RZT 50 inch zero turn with the Kawasaki 22.0 engine. It only has 140 hours on it.

It runs very hard almost like it has bad gas. So I added StayBil and some fresh gas. It doesn稚 run any better. It runs like someone is pumping the gas and shutting it down in an off /on mode repeatedly. The way to get it to run smoothly is to pull up on the chock. If you get the chock up just right it will run rich and a little better with a full throttle.

Last spring it ran bad like this after the second tank of gas and I did a lot of diagnostics. I drained the gas out and put in fresh gas. I opened and blew out the fuel line, same with the fuel filter. I cleaned the air filter. I checked the sparks plugs and reseated their connections. It didn稚 seem to run much better. When I took it into a repair shop, the technician got on ran it hard with the chock on for about 3-5 minutes and it ran good again.

I haven稚 done any of the above diagnostics which I did last Spring. I tried to do what the tech did, and it hasn稚 run any better. Should I run the same diagnostics as before . . . or what have I forgot?

 

[OldMachinist]

Most likely you've got some varnish or crud stuck in the main jet or jets of the carburetor. I would remove the carb and dis-assemble, and blow out all the ports and passages with carb cleaner if you're mechanically inclined. If your uncomfortable taking it all apart just remove the carb and take out the two main jet plugs and spray the main jets out. I think this is the right parts breakdown for you carb.

 

[francis@mylegaltech.com]

Your suggestions worked out. You gave me the confidence to pull out the carburator from the block and spray in some cleaner. I did not take it apart just away from the engine enough to get access to the manifold and spray in some cleaner. When I first started it up, it ran as bad as before, but this time when I gunned it, it began to clear up. It has been running just fine for the last 2 hours. Thanks.