Many engine issues like the engine dying out or the engine, not idling can be simply fixed with little adjustments in your carburetor.

Stock Carburetor Adjustments:

In this guide, you can learn how you can adjust the idle screw and the fuel/air mixture screw for both the stock carb that comes with your predator 212 (or other engine Honda clones) and the Mikuni carb and the clones.

Idle Screw:

The idle screw can be found eight above the idle jet.

The Idle Screw’s Function:

The idle screw will control how much the throttle closes in the idle states. If you turn on your idle screw, it’ll stop the complete closing of the throttle when your engine is idling and therefore upsurge the idle speed. Likewise, if you loosen its screw, the throttle will shut completely in an idle state and reduce the idle speed.

Also Read: off-road go-karts

Adjusting The Idle Screw:

If you desire your engine to have higher RPM while idling, you will have to tighten its screw so that the throttle does not close fully on idle and vice-versa; if you desire lower RPM, then loosen its screw.

Air-Fuel Mixture Screw:


It’s gonna control the amount of air that enters your engine. If you tighten it, it’ll make the mixture rich, and if you loosen it, the mixture will become lean.

Adjusting The Air-Fuel Ratio:

Before talking about any adjustments, the significant thing to note is that the stock carbs of the majority of the new Predator 212 are non-adjustable; that’s because of government regulations for protecting the environment. If the air-fuel mixture screw is fixed, then you will have to either clean the carburetor or change the idle and main jet to resolve the carburetor problems. Unluckily, you cannot just make a rapid adjustment.

The other choice is to get the new adjustable carburetor; they just cost ten to fifteen dollars. If you have the adjustable screw, then you can simply tighten it for the richer mix and loosen it for the leaner mixture.

Step-By-Step Process:

  • Keep the engine running.
  • First of all, adjust its idle screw to the idle speed of your preference.
  • Observe the engine’s sound. If the mixture is really rich, your engine will sputter, and if it’s too lean, your engine will generate a bogging sound.
  • Tighten its air-fuel screw if your engine is bogging, and loosen it when your engine is sputtering. Locate the balance.

Mikuni Carburetor Adjustment:

Mikuni VM22 and the clones are the well-known carb upgrade for mini bikes and go-karts; they aren’t as easy a design as your stock carburetors.

Note: The majority of the Mikuni/Chikuni carbs have a #98 main jet, which is not large enough; if you have the stage 1 air filter installed, your engine will run lean. In these situations, you have to get the larger jet (at least #120); adjustment alone would not resolve the problem.


Step by Step:

  • Take the screwdriver and turn the fuel/air screw all the way in but not really tight.
  • Now loosen the fuel/air screw to 1, and 1/2 turns out.
  • Start the engine.
  • Once your engine starts running, loosen or tighten it 1/4, turn at a time and note the RPM. You have to locate the position at which the idle RPM is max.
  • Keep making 1/4 turns until you locate the max RPM.
  • Once you locate the highest idle RPM position, loosen its idle screw.

If the throttle receptiveness is not great, then it is frequently because of the lean mixture; you will have to adjust the needle in this case.

What To Do If The Carburetor Does Not Have The Adjustable Air/Fuel Screw?

The majority of the carburetor problems can be fixed by simply cleaning its pilot jet and main jet. If your engine is not starting, or it is starting but dies out at full or half throttle, you’ll have to take the carb apart and clean all the parts.

At times, bad fuel can also cause such problems, so make certain to check the fuel tank. Basically, having the adjustable screw permits for a rapid fix, so not having one will need more work.

Read More: