Thursday, December 8, 2011

ATV Throtle Cable Replacement

I had a Yamaha Grizzly in the shop with a bad throttle cable.  Whenever the temp dropped below freezing it would get stuck.  There was obviously some moisture in the cable somewhere.  When I checked it out I discovered that the jacket on the cable was broken in the middle and it would need to be replaced.

I removed some of the plastic body work and took the covers off the throttle control on the handle bar and the cable cover on the side of the throttle body.  To provide a little slack in the cable to remove it I opened up the throttle butterfly and stuck a screwdriver in there to hold it open.

Once there is a little slack in the cable it is a simple matter to twist the cable end around and slide it out of the slot.

The end on the handle bar comes apart in the same way.  Get some slack in the cable and twist it around so that it can lift out of the slot.  Once the cable ends are free the outside housing unscrews from each end.  When installing the new cable remember to adjust the cable free play and use the lock nut to hold it in place.

This last photo shows the old failed cable assemble and the new replacement.  There are two pieces of plastic tubing slipped over the cable housing to protect it from abrasion.  Where the two pieces meet in the middle the housing broke.  I don't understand why Yamaha made it this way?  If the outer tube was one piece it would avoid that kink in the middle.  When I installed the new one I put a few wraps of electrical tape around it to try and avoid this problem.

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.