Sunday, December 4, 2011

Polaris 120 Carb Cleaning


In my last post I talked about drive chains being the number one problem with 120 or mini snowmobiles.  A less common problem is carburetor troubles.  But if you put enough water and dirt in the gas tank it will eventually give you trouble.


The carburetor on this Polaris machine is located on the back side of the engine.  The carb is slides over two studs that are threaded into the engine.  To remove it you need to pop the cover off the plastic airbox and remove two nuts.  The orange colored arrows show the location of the studs. 


Here is the carburetor on the work bench. 


When I pulled the float bowel off the bottom it was full of water, rust, and dirt.


Here are all the important parts.  The blue arrow points to the pin that holds the float in.  It should slid right out to remove the float, sometimes you may have to tap on it

The Green arrow points to the float needle.  On most carbs this is a separate part, but here it is connected to the float.  This needle controls the flow of gas into the carb.  If you have a machine that lets the gas run through the carb and flood the engine your problem is right here.  Occasionally something will get stuck by the tip of the needle and prevent the needle from shutting off the flow of gas.  On my old Polaris 440 I had that problem and when I took the carb apart there was a 12" long piece of musk ox hair stuck there!

The red arrow points to the main jet.  If you have a machine that seems like it does not have enough gas/ only runs with the choke on then the main jet may be clogged.  The jet is made from soft brass, make sure you have a screw driver that fits well if you are going to take it out.


This is what it looks like all apart..  Once the needle/float and the jets are removed I simply scrub it out with a little carb cleaner and blast it clean with compressed air.  Be careful putting everything back together, it is all soft brass and aluminum.



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