Non adjustable carb

[staninlowerAL]

When doing some much needed tune up on my recently acquired CC RZT 50 w/B&S 22hp engine. I purchased and installed a replacement (not OEM) air filter and pre-cleaner. I noticed immediately that the engine did not run as smoothly as it did at lower rpm before I installed the filter but smoothed out when a little choke was applied so I thought that perhaps the carb needed tweaking a bit since the old filter was pretty dirty. A thorough examination of the carb resulted in no adjustment points found for air or fuel so I went to the Owners Manual and found that the carb has no adjustment other than change the jet if operated at high altitude. (Picture from manual is attached). I'm not a carb genius or expert but do have a bit of practical experience with old iron but this is my first experience with a non-adjustable carb. How common is this? Thanks for sharing any feedback.

Forgot to add that I cleaned and reinstalled the old filter and the engine ran with no issues.

[Gary Dotson]

Thanks to the EPA, that's pretty common now. Running a little on the lean side is exactly what they want it to do. EPA also requires that no rebuild kits be available for them. Fortunately, new carbs. are pretty reasonable, now days. Your slightly dirty air filter seems to be the tune-up that it needed.

[staninlowerAL]

Thanks for the info, live and learn.

[BigBill]

Is the engine hunting? Not a even idle it goes fast than slow. Starving for fuel if you close the choke she runs better, less air more fuel? I’d seafoam it so the carb gets the gum out of it.
I’d put seafoam in the gas tank run it then let it soak. I had a new generator with a gummed up carb. I did the seafoam trick let it soak and off she ran. This ethanol gas I can’t say what I want it’s not good. I been buying non ethanol fuel in cans and non ethanol two stroke husky mix in cans.

My neighbors John Deere mower even the local lawn guy couldn’t fix it. It had to go to the dealer.