& Engine Work
Clutches & Parts
Ski & Spindle Assy
Steering & Tie Rod
Drive Train & Brake
Slides, Idlers, Track
Chassis & Bumper
Hood & Windshield
Belly Pan & Exhaust
Gas Tank & Seat
Cylinder & Case
Piston & Crank
Information and submit
Ski Doo 120
Pro Ice West
NW MN & E. ND
Kitty Cat Racers
Kitty Cat Basic Performance Setup
Following is a list of initial steps you can do to get more performance out of your Kitty Cat.
Bypass the Governor: This will increase the engines RPM so the engine runs stronger and spins faster thus turning the gears faster ultimately resulting in more speed. There are three ways to bypass the governor depending on how much time you have and what the long term intent is for reinstating the governor system at a later time.
- Quick or temporary bypass – If you follow the throttle cable down from the handlebar you’ll see where it connects to the linkage. On that linkage you’ll see a spring that stretches each time you squeeze the throttle lever. This is the spring that stretches when the governor is overpowering the throttle lever to restrict the RPM of the engine. Simply put a few small zip ties through the spring to keep it from stretching, making it essentially a solid rod. This allows the driver to overpower the governor and forces the RPMs higher. The disadvantages to this method is that the drivers thumb can get tired fighting the governors resistance and the governor continued to try to work and can slow the RPM of the engine down slightly. This leaves all OEM part intact and is ISR legal to do. (COST = a couple small plastic tie wrap)
- Easy to reinstate bypass later – Remove the gear case cover (remove oil first) and you’ll find two gears. One gear will have a mechanism mounted to it that contains a few small square metal weights that swing outward when the RPM increases. This is the mechanism that operates the governor. The cage in which the square metal weights are held, simply use a channel locks and squeeze the top edges of the cage closed against the weights. This prevents the weight from being able to swing out to operate the governor. This leaves all OEM part intact and is ISR legal to do. (COST = None)
- Permanent governor bypass – Out of the gear case you’ll see a shaft protruding about an inch that has a lever connected to it. That lever is also connected to the rest of the throttle linkage. The lever is squeezed onto the shaft with one bolt. First install a zip tie around the shaft between the points where the lever connects to the shaft and tighten firmly. This will help prevent the lever from falling off the shaft in a sled roll-over situation thus resulting in an unintentional wide-open throttle. You may also want to place a mark on the shaft and lever so you can realign the two later if you decide to reinstall the governor. Now loosen or remove the bolt that mounts that lever onto the shaft. The shaft should now freely turn inside the lever thus eliminating the governor’s ability to operate. This leaves all OEM part intact and is ISR legal to do. (COST = None)
Helpful Hints: With the increase in RPM, it's recommended to either upgrade the connecting rod to an updated “slit rod” for increased lubrication or gear the Kitty Cat down with a new sprocket to keep the engine from over-revving. You will also want to consider changing the carburetors 1.5 needle & seat to a 2.0 size to ensure enough fuel is getting into the engine.
Change the Carburetor Jetting: This will increase the amount of fuel that can enter the carburetor and also increase engine performance by allowing the engine to run cleaner.
- Changing the Needle and Seat (N&S) - The OEM carburetor comes with a #1.5 needle and seat (N&S), which is the device that controls how quickly fuel can run from the gas tank into the carburetor. With stock RPM a #1.5 N&S is sufficient, but when someone bypasses the governor and increases the RPM there is a greater demand for more fuel. If the N&S size is not increased, the bowl of the carburetor will run out of fuel and the engine will cut in and out resulting in slowing the sled down and lack of sufficient lubrication. To correct this problem, replace the original #1.5 N&S with a new #2.0 N&S to increase the fuel flow rate and keeping the carburetor bowl full of fuel. To replace the N&S, remove the bowl of the carburetor. This is easier down with the carburetor removed from the engine. You’ll see a circular plastic float that’s held in place with a steel pin. While holding the carburetor upside-down, carefully remove the pin. Now carefully remove the plastic float being careful to not drop the ‘needle’ from under the float. Now you’ll see the needle and seat (N&S) assembly screwed into the bottom of the carburetor housing. Carefully remove the needle from the seat and place in a safe location so it doesn’t get lost. Now unscrew the seat from the carburetor housing and put both needle and seat in a plastic bag or container. Now install the new seat and then place the needle inside the seat. Replace the float using the steel pin while centering the pin. Reinstall the bowl. (NOTE: If you’re also upgrading the main jet, complete those steps below before reinstalling the bowl.) (COST = #2.0 N&S is $24.95)
- Changing the Main Jet - The OEM carburetor comes with a #72.5 main jet (except for 1977 which was a #77.5) which allows lots of fuel/oil into the cylinder and actually makes the engine run a little rich for extra lubrication. With a 2-stroke engine, they run the best when leaned down. Of course when leaning down an engine you always risk engine failure, but in order to race I’m not aware of anyone running anything more than a #70 main jet. The #70 main jet leans the engine down slightly, but cleans up carbon buildup and increases engine performance. Some experienced racers will go down to a #67.5 and something even a #65 main jet which is risky, but I’ve never experienced or heard of an engine failure for running a #70 main jet. To change this out, you’ll need to remove the carburetor bowl and you’ll see a brass screw on the side of the nozzle housing that protrudes into the bowl. That brass screw is the main jet. Remove and replace with a #70 main jet. (COST = $5.00)
Spark Plug: This is a personal choice per racer. The standard spark plug is a NGK BR6HS, which works just fine. However, if you are looking for even better performance, you can upgrade to a better spark plug. The next better plug is a NGK BPR6HS, which is the same as the original except is has a “projected tip”, which gets the spark into the cylinder deeper. The next better spark plug is the BPR6HIX iridium spark plug. This plug uses a rare earth metal and has a fine electrode creating a bigger spark. It also takes less energy to fire, so if you have a weak coil this spark plug will compensate for it. The iridium plug is also less likely to foul out. (COST = BPR6HS is $2.95, BPR6HIX is $9.25)
Gas Tank Location: Since the Kitty Cat utilizes a gravity flow gas tank system (no fuel pump), the maximum fuel flow is essential. There are a few recommendations to achieve this.
Relocate and elevate the gas tank – I use balsa wood and make a block to lift the tank higher on the fuel tank bracket. You can get up to about 2” more height. When possible, I also rotate the gas tank to get the gas line as vertical between the gas tank and carburetor as possible.
Install a 90 degree elbow instead of the OEM fuel shutoff/filter – If your club will allow it, you can change out the OEM fuel shutoff/filter with a 90 degree elbow and if needed, an in-line fuel shutoff. This will remove the slight restriction of the shutoff/filter. (COST = Elbow is $13.02, In-line shutoff is $14.95)
Tether: In order to be ISR legal, and a responsible parent, you’ll need to install a tether. The tether is a device that’s connected to your engine wiring and if the device is activated the engine is automatically shut off. The device is activated by having a tether cord connected between the device and a driver so that if the driver falls off the sled the cord pulls a plug out of the tether device, thus killing the engine and preventing injury. The tether is installed by connecting the two wires from the tether into the two ignition wires coming from the engine (typically black and brown). (COST: $39.82)
- Place a pipe or socket under the ski and move it back and forth until you can find the center of down pressure from the spindle.
- Mark that spot on the ski.
- Put a mark on the center of the carbide.
- Hold the carbide up to the ski and align the two lines.
- Now move the carbide ½ to ¾ inch towards the front tip of the ski.
- On the bottom of the ski, mark where the two studs from the carbide touch the ski.
- Drill holes in the bottom of the ski for the studs to mount to.
- Mount the carbide onto the ski.
- Locate a place on the console you want to locate the tether and mark with pencil or marker.
- Make sure there is nothing behind the console that will interfere with the back of the tether.
- Drill a ½” hole in the console.
- Remove the tether cord from the tether base.
- Remove the mounting nut from the tether base.
- Push the tether base through the console from the back.
- Install the mounting nut onto the tether base and tighten.
- Reinstall the tether cord.
- Cut the ends off the tether wires and strip ¾” of insulation from the wire ends.
- Locate the brown wires that come out of the engine below the carburetor.
- Strip back a portion of the wire insulation anywhere on the brown wires coming out of the engine.
- Attach the tether wires to the brown wires by twisting the tether wire ends around the brown wires.
- NOTE: The wires can be mounted to either brown wire, it doesn’t matter which one.
- You can solder the wire if you want to which is best, otherwise wrap well with electrical tape.
- Test the tether to ensure it kills the engine.
Kitty Cat Setup:
- You will want to bypass the governor to allow the engine to rev higher making the sled go faster. You can do this by the following ways:
- Put a zip tie through the linkage spring allowing the driver to squeeze the throttle and the spring not extend.
- Remove the side cover (gear case cover) and with a pliers squeeze the two mounting points on the governor arms so that the weights can’t swing out.
- You may find that with the governor bypassed, the engine may run out of fuel and you may notice the engine cutting out after about 30 seconds of hold the throttle wide open. This happens because there is only a 1.5 needle and seat in the carburetor and that’s what restricts how fast the fuel can run from the gas tank into the carburetor. You most likely will need to replace the 1.5 needle and seat with a 2.0 needle and seat. I sell them for $24.95.
- The engines come from the factory with a #72.5 main jet that controls how much fuel enters the engine through the carburetor. This jet makes the engine run rich. Most, if not all, racers run with a #70 main jet which allows the engine to run more clean and faster.
- When you become competitive, many racers run with a lighter lubricant in the gear case. Manufacturer calls for SAE w30 engine oil. Some run with either lighter engine oil or even two stroke oil.
- You can switch out your spark plug to a better firing one. Stock was BR6HS. You can use BPR6HS which has a “projected tip” and gives better performance ($2.95) or an Iridium BPR6EIX which uses a rare earth element that allows for a bigger spark and less chance of fouling out. The Iridium plus sells for $9.25. I have both plugs in stock.
- If you decide you really want to race competitively, the next thing is major. You’ll want your crankshaft upgraded and straightened. The factory connecting rod doesn’t have good lubrication ports, so Arctic Cat put out an upgraded rod that has slits in the sides allowing direct lubrication to the crank pin bearing. On a crankshaft rebuild, the connecting rod is replaced with the upgraded slit rod, then the crankshaft is straightened. Every crankshaft from the factory is out a bit and causes the engine to shake and slows down the rotation of the crankshaft, thus slowing down the snowmobile. Once the crankshaft is straightened the engine will spin more freely and speed up the engine.
- In entry level stock classes you’ll need to run a stock clutch. You’ll want to consider a new or refreshed clutch because with the heating and cooling of the clutch the spring loses its tension and lowers the engagement rpm making you slower off the line. You may also have worn bushing issues that make the drum slop around. I carry a full line of clutches and clutch parts.
- Between race weekends you should blow any debris out of the clutch before the next weekend of racing.
- Chain and Sprocket:
- Make sure you have a good quality and newer chain. When the pins of chain begin to wear it creates a ‘stretching effect’. This effect can cause the chain to wear out the teeth on your sprockets. There is standard chain that has a low break and wear rating that sells for about $8 per length and then there’s space chain that is a much higher quality chain that lasts about 8 times longer and sells for $10.
- If you want to treat your chain, please don’t use a spray on chain lube. It gets all over everything and can cause your clutch to slip as well as other things. The proper treatment is to put the chain in a metal pan of SAE w20 or w30 motor oil and bake in an oven at 300 degrees for about 20 minutes. Then hang the chain from the ceiling over the pan for 24 hours to let the oil run out. For better performance you can substitute engine oil with Energy Release or Slick 50 that will coat the chain.
- In most stock classes you’ll need to run a 42 tooth driven (rear) sprocket. You can use the OEM sprocket to get started and if you continue racing you’ll want to purchase a Kitty Cat quick change hub and exchangeable sprocket(s). I sell the hub for $35 and all kitty cat sprockets are currently $25.
- Here’s where you can gain quite a bit of speed and performance at very little cost.
- You’ll want to recondition each bearing of the undercarriage.
- Remove the bearing from the chassis (front drive, rear idler, and bearing bogie wheels).
- Remove the side dust cover from the bearing exposing the ball bearings. Be careful to not bend the dust cover as we’ll use it again.
- Using carb or brake cleaner or other similar solvent, clean all the grease out of the bearings.
- Drill a small hole in the dust cover, just large enough for a solvent spray nozzle to fit through it.
- Spray a small amount of lubricant onto the ball bearing and spin the bearing to ensure it spins freely.
- Replace the dust cover onto the bearing. Test to make sure the bearing still spins free. If it doesn’t, the dust cover is pushing on the center race of the bearing and it needs to be adjusted.
- Once the bearing spins free with the dust cover on, return is to the drivetrain and go to the next bearing.
- When all bearing are done, you can spray a lubricant into each bearing and see how well they spin. I personally use a white lithium grease because it holds in the bearing much better.
- If you have a newer model Kitty Cat and you don’t have bearing bogie wheels, then you have the plastic bushing type bogie.
- To recondition the bushing bogies remove all six from the drivetrain.
- Clean any rust from the axles and bogies.
- With a dremel or die grinder, reach inside the bogie bushing and grind a small groove all the way around the busing about half way through.
- Now use the drill bit you used on the dust covers and drill a hole through the bogie bushing at an angle down to the groove.
- Now you’ll be able to put the solvent straw into that hole you drilled to spray lubrication directly in the middle of the bushing.
- Make sure you adjust your track as loose as possible without the drive sprocket slipping on the track. The looser the track, the faster you go.
- The older Kitty Cat’s had a low profile track that was thick and stiff. Most aggressive racers will replace the old stiff track with a 1999 Kitty Cat track.
- The Kitty Cat steering is terribly loose right from the factory. You need to tighten up all the linkage, skis and spindles.
- The cheapest and easiest fix is to use aluminum pop cans and cut them into strips (shims) that can be wrapped around bolts and spindles to take up the slop. Be sure to use a little lubrication on the aluminum shims.
- Some clubs will let you drill out the spindle mounting holes and put larger bolts in there instead of using shims and also on the bolts that connect the ski to the left spring.
- For the ultimate option, you can install oil impregnated bronze bushings in your bulkhead that your spindles fit through. This tightens up the front spindles.
- Front Steering arms are an additional option. Most clubs will allow you to replace the tie rods with aluminum steering arms and heim joints. This takes lots of the steering slop out of the linkage.
- Running one carbide on the right ski in stock class is more turning control than you need. Just leave the standard wearbar on the left side.