How to Tune a Snowmobile Carburetor?

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A snowmobile is a single or double passenger motorized vehicle. It contains skis in the front with an engine-driven continuous track to propel it. Snowmobiles are a great mode of transport and recreation during winters in areas with lots of snow. Problems in snowmobile parts, like the carburetor, can affect its functioning. The carburetor is a critical component of the snowmobile that determines its performance. It is responsible for powering the engine and contributing to the snowmobile’s speed.  

How Does a Carburetor Work? 

A carburetor, also known as a carb, is a vital part of a non-fuel injected internal combustion engine. It mixes fuel and air in a predefined proportion to allow combustions that power the engine. The throttle of the snowmobile is directly connected to the carburetor. When you “hit the throttle” in your snowmobile, you open up the throttle valve to the carburetor to allow air in and control the rate of combustion. 

Engines with more than one cylinder will have more than one carburetor. 2-stroke or 4-stroke engine snowmobiles can have two or four carburetors. 

Components of a Carburetor 

A snowmobile carburetor is made up of many components. These are listed below with their primary functions: 

Pilot Air Jet: It controls the air that enters the motor from the idle circuit. The larger the pilot jet, the more air will enter to lean the idle mixture. 

Main Jet: The main jet is similar to the pilot jet in style and function. The only difference is a washer that is located on the main jets. This washer should not be removed.  

Fuel Screw: The fuel screw controls the low-speed air/fuel mixture when the engine is idle. Turning the fuel screw out will make the mixture richer.  

Needle Jet: A needle jet is pressed into the carburetors and cannot be replaced 

Starter Jet: A starter jet meters the fuel entering the motor when choked. The higher the number on the starter jet, the more fuel will pass.  

Tuning a Snowmobile Carburetor

Many times, when you are out on your snowmobile, you notice that it is not performing to its optimal level. There may be various potential causes of the decreased power in your snowmobile. Some of these may require heavy repairs. But most of the time, a simple carburetor tuning can bring back your snowmobile to peak performance. A few simple adjustments to the carburetor can help the snowmobile return to full speed. Here is what you need to do to tune your snowmobile carburetor: 

Adjusting the Low-Speed Needle

The first step in tuning a snowmobile carburetor is adjusting the low-speed needle. Here are the steps to adjust it:

  • Ride the snowmobile for a few minutes to warm it up
  • Remove the access panel by releasing the clips on the outside of the engine compartment at the front of the machine. 
  • Turn off the snowmobile engine.
  • Look for the low-speed needle. It is located on the left side of the carburetor when you are at the front of the machine with the access panel open.
  • Slowly turn the low-speed needle clockwise until it is lightly seated. You can insert a flat-head screwdriver into the groove on top of the needle to turn it.
  • Now turn the low-speed needle for 1.5 rotations in the counterclockwise direction. Start the engine again. 
  • Let the engine run for at least five minutes before turning it off. 

Adjusting the Idle Stop Screw

  • You must adjust the idle stop screw only when changing the idle speed. 
  • Set the idle speed to 2200 rpm. 
  • If the idle stop screw gets adjusted, the low-speed needle will have to be readjusted again. 

Adjusting the High-Speed Needle

The second step in tuning the carburetor is adjusting the high-speed needle. To do this, you must:

  • Turn off the engine and look for the high-speed needle on the carburetor. It is usually located on top of the carburetor.
  • Turn the high-speed needle in the clockwise direction till it is lightly seated. It usually requires half a rotation with a flat head screwdriver inserted in the groove on top of the needle. 
  • Turn the needle out with 1.5 rotations in the clockwise direction using the flat head screwdriver.
  • Start the engine, ride the snowmobile at high speed on level ground for five minutes and stop.
  • Turn the high-speed needle again for 1/8th of a rotation in the clockwise direction. 
  • Test drive the snowmobile again on flat ground.
  • Repeat this process till you get the desired performance from the snowmobile. 
  • Once you achieve the desired speed and performance, turn the high-speed needle again for 1/8th of a rotation in the counterclockwise direction to complete the tuning process. 

Precautions to Take while Tuning a Snowmobile Carburetor

While you may be able to tune your snowmobile carburetor by yourself, you must be very careful. Here are some precautions to take when tuning the carburetor:

  • Ensure the high-speed needle is not too lean. If it is too lean in the clockwise direction, it can cause serious damage to your engine. 
  • Don’t set the high-speed needle with the track off the ground with the engine in a no-load situation. To prevent engine damage, it must be under load. This will prevent overspeeding and also help you achieve proper carburetor adjustments. Your cooling fan belt will get damaged if you overspeed your snowmobile. 

If you are using your snowmobile at a high altitude, it will require a leaner carburetor setting. Here is a ballpark rule for the leanest possible high-speed setting:

Above 5000 feet altitude (1524 meters) = 5/8 turn open (300), 1-turn open (400, 600 and 800) 

Having some information about snowmobile parts and how to troubleshoot them can be extremely useful. But along with repair knowledge, you should also know where to source quality snowmobile parts. offers aftermarket snowmobile parts. All parts are designed, developed, and tested to ensure durability and performance. Whether you are looking for engine parts, accessories, or performance kits, you will find it all here. 

 Straightline Performance,

15250 Hornsby St. Forest Lake Minnesota 55025,


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