"Doesn't seem to lean"
Ok, I'd make sure it's not too lean. Every carb has it's own sweet spot, but 2 1/8 to 2 1/4 turns out on the main needle is pretty close for most tractors. Here's how I adjust mine:
Start the engine, let it warm up to operating temp. Advance throttle to wide open. Now, you can start playing with the mixture screw. Turn the needle out 1/4 turn at a time until you get black smoke, galloping, etc. and then back in until it just smooths out. Now, idle it down and ram the throttle back to WOT. It's too rich if it stumbles and there's black, sooty smoke. If you get stumbling and black smoke, lean it 1/8 to 1/4 turn and try again. Repeat until it'll go from idle to WOT without black smoke and it should be just about right. It wouldn't hurt to turn it out 1/8 turn after that. Air-cooled engines should run a little rich. NOTE: that method only works well if your engine is in relatively good condition. If it's not in good condition or it smokes such that you can't see the black smoke, you can use a leaning method similar to what we use is small airplanes that don't have a cylinder head temp gauge.
For this method, it's real helpful to wear earplugs to deaden PTO clutch noise and hydro whine (if applicable) to make this a bit easier. Start the same way by warming the engine up. Run it at WOT, and SLOWLY lean the mixture until it really bogs down, then turn it out again until you get an rpm rise and then a drop. After it drops again, turn it back in to where the engine runs the fastest. That should also be correctly set.
If you've got a leaky carb, take care of that first. Adjust the float or put in a carb kit as necessary.
You can also put a capful or two of seafoam in the gas tank to clear out the carbon. Similarly, you could fill a spray bottle with water and spray it into the carb with the engine running. Either method should decarbon the combustion chamber.
One last thing....sounds like your carb is held on with the wrong fasteners. All of mine are hex bolts with a screwdriver slot in them. They are relatively easy to remove and reinstall.
|