If your Predator 212 is only running with the choke turned on, then the problem is the Air-Fuel Mixture. To be specific, the engine is getting too much Air but not enough fuel for combustion. So when you turn on the choke, some of the air gets blocked and the engine runs smoothly.
The fix is pretty simple, you can either buy a new carburetor or clean the pilot and main jet of your existing carburetor. Usually, the culprit is a clogged-up pilot jet, however, you should clean your whole carburetor just to be sure.
Here’s a step-by-step guide:
1. Remove the Air Filter
Removing the Air Box is pretty easy, simply take a 10 mm socket and unbolt the 2 bolts shown in the image. Make sure that the lever is in the middle, it will make it easy to remove.
Once the bolts are out, you’ll need to disconnect the air filter box from the vent hose that connects with the cylinder head. Then just pull the Box out and you’ll be able to see the carburetor.
2. Remove the Carburetor from the Engine
Once you take off the airbox, you’ll be able to see the carburetor (like shown in the image). Here’s how to remove the carburetor:
- Use a pliar to strech the fuel line clamp.
- Disconnect the fuel line and make sure to block the hose with either a pliar or a bolt, otherwise fuel will start coming out.
- Move the carburetor slightly forward to slightly loosen the spring and rod.
- Unhook the spring and the rod.
3. Disassembling the carburetor
As mentioned before, the most likely component that causes this issue is the pilot jet, so let’s first take out the pilot jet.
The pilot/idle jet is placed just below the idle screw. To take it off, first, you’ll need to unscrew the idle screw.
The jet itself is pressed in the hole with an o-ring, you’ll need a flat head screwdriver to take it out.
To take out the main jet you’ll have to first drain the fuel in the carburetor by unbolting the drain bolt and then unbolt the main bolt. Then remove the bowl.
4. Cleaning the Pilot Jet & Main Jet
This is what an Idle/Pilot jet will look like. The brass that is in the bottom has a small hole in it, that is how it sucks in the fuel from the carburetor bowl. In your case, the hole is most likely jammed which is causing the issue.
Either take a carburetor cleaner and spray it through the hole or take a fine wire and run it through the hole.
That will solve the problem at low speed, however, if your engine is turning off in the later stages/higher rpm the main jet is likely the issue.
This is the main jet that you’ll see when you remove the bowl. (There will also be a plastic float, that was removed before taking this pic)
Take a flathead screwdriver and take out the main jet.
Similar to the pilot jet cleaning, spray some carburetor cleaner or run a slim wire through the holes.
If you slightly tap the container of the main jet, the emulsion tube will also fall out. You can/should clean that too.
Now finally put everything back together. Make sure to install the gaskets that came out with the carburetor. If they broke during removal, you’ll have to get new gaskets.
Instead of cleaning, you can replace the carburetor. A Chinese replacement carb only costs $10 and comes with gaskets, etc.