Welcome to the Troubleshooting page. I hope you will find it helpful.
ENGINE WILL NOT START: Remove the plugs. If fuel is reaching the cylinders, they should be wet, if they are cold. Too much fuel and oil will foul the plugs and cause a no-start problem. Fouled plugs also can indicate that your ignition system is not up to par. Remove the plug(s) and ground them on the engine. Crank the engine over, and watch the plugs. They should spark bright, blue sparks. If they do not spark, go to the NO SPARK area of this page. If the spark is weak, or yellow, you will need a new coil. If there is NO fuel on the plugs after cranking, check the fuel system for trouble. Here are the possibilities:
1. No fuel in tank
2. Carburetor gummed or dirty. This is imporatant. Even if you use Sta-bil every year, the carb can gum up. Remove the float bowl and inspet the floats, and most important, the fuel inlet needle.
3. Fuel pump diaphragm frozen or damaged, install repair kit.
4. Clogged fuel filter or lines.
5. Fuel pump impulse line dissconected or cracked.
In the case that you have both SPARK and FUEL, check under flooding, or check the engine for low compression, old gas, choke in wrong position, or the carb may be badly adjusted.
ENGINE STARTS AND THEN STALLS: This can be caused by many different problems. If your sled is pre-mix, make sure you are using the correct ratio of fuel and oil. If the plugs are fouling, this is a sure indicator. remove them, and either temporarily clean them, or replace. This can also be cause by a clogged fuel filter and lines. Check the compression by removing the plugs, turning the ignition off. Then place your thumb on the plug hole. Have a helper pull the engine over sharply. This should blow your thumb off of the plug hole. If it does not, you do not have adequate compression to make the engine run. The points may be out of adjustment. Clean them, and check for the proper gap. If any of the springs on the exhaust system are missing or loose, you will be lucky to get the engine to sputter, they are very important.
ENGINE DIES DURING USE: This can be caused by over heating. Once again, if the fuel oil ratio if off, this can happen, due to running too rich, or lean. If the coil is weak, this can happen. Make sure the carburetor is adjusted proerly. Check the fuel pump, and it's impulse line. Makse sure the air box is clean and un-obstructed.
POOR PERFORMANCE: Make sure the muffler and air box are not clogged. The ignition timming may be off. Check the plugs. Keep in mind that the ignition systems on most 2 cylinder engines are independant of eachother. This means that while one may have a stuck point or damaged coil, the other one may be fine and fire the plug. Also, make certain that the brakes are not dragging. Check the pistons, rings, and cylinders. Loose cylinder head gaskets, or loose head nuts. Leaking crankcase seals ( check by spraying carb cleaner on the PTO end shaft, behind the clutch, if the engine runs better, then it's leaking seals). Incorrect fuel oil mix. Incorrect, or improperly gapped spark plugs.
EXCESIVE SMOKE: Pretty much only one thing that can cause this. Either the fuel oil mix is too much. Or, the oil is cheap, like TCW-3 or NMMA. Oil that is atleast semi-synthetic and JASO certified should be used in snowmobiles. If the engine is running on one cylinder, this can happen also. Low compression can cause this also. There is also a possibilty that the sled is flooding.
ENGINE BACKFIRES: This is generally caused by the timming being off, or a sheared flywheel key. Also, a leak in the exhaust system can cause this. If the plugs are fouling off and on, this can happen, when the fuel collects in the cylinder that isn't firing, and then boom, the plug fires, and on and on. Water in the gas, or old gas, can be a culprit. Make sure the floats are properly adjusted and the inlet needle is clean.
ENGINE OVERHEATS: The following are generall causes. Improper ignition timing. Dirt or grass in the cooling fins ( NOTE: if the sled has been grass dragged, this is a very common problem). Missing or bent engine housing or fan housing. Carburetor mixture screw turned too lean. Wrong fuel oil mix. Missing or broken fan blades, or cooling fins. Cylinder heads not installed correctly.
ENGINE FOULS PLUGS: This seems to be the #1 snowmobile problem since Ski-Doo. It seems to start with either cranking the engine until it's rope breaks, with occasional pops out of the carb, or maybe a quick rumble from the engine. Or somtimes it happens when you are zipping along, and suddenly BAM. The sled can't even pull you, so you push it home, the throttle half open, going 5 mph. Most guys just buy 12 packs of NGK in the back of their sleds. But there are ways to at least reduce the amount of plug fouling. Start with the correct fuel oil mix. Below, is the correct mix for all of the sleds.
Aloutte Machines: 20:1 JLO or Kohler engine. 25:1 Sachs engine
Alsport: 20:1 with 87 octane gas
Arctic Cat: Kawasaki engine: 20:1 Wankel: 25:1 Spirit: 20:1 Use 87 octane except for El tigre and pantera 5000, these sleds use Premium fuel.
Ariens: 24:1 Sachs engine. 20:1 Kohler engines. Regular gas.
Arlberg: 25:1 use SAE30 or SAE40 heavy duty motor oil.. Regular gas
Auto Ski: 20:1. Regular gas.
Boa Ski: 20:1. Kohler, 40:1 with premium gas
Boatel: 25:1
Bolens: 20:1 Regular gas
Chaparral: 20:1
Columbia: 20:1 for JLO. 25:1 for Sachs.
Dauphin: 20:1 Regular gas.
John Deere: 20:1, for units 1974 or earlier. 50:1 1975 or newer. 90 octane or better on early models. 88 octane or better on later models.
Eskimo: 25:1
Fox Trac: 20:1 Regualar gas
Frederick-Willys: 20:1 Regular gas.
Gilson: 20:1 Regualar gas.
Harley-Davidson: 20:1 Use premium fuel in Y440
Herter's: 20:1 for Kohler. 20:1 for JLO. 40:1 Lloyd. 25:1 Sachs.
Homelite: 20:1. Sleds with Hirth motor: 25:1
Hustler-Rustler: 20:1. Regular gas.
Jac-Trac: 20:1
Jetstar: 20:1
Kawasaki: 20:1
Kometik: 20:1. Regualar gas.
Larson: 20:1
Mallard: 20:1
Mercury: 20:1. Trail Twister and Sno Twister require Premium fuel.
Montgomery Ward: 20:1
Moto-Ski: 16:1 For models 1965-1972. 50:1 Full synthetic for all others. ( As a side note, 20:1 works well with the Rotax motors, with standard oil).
Northway: 25:1 for Hirth. 20:1 for CCW or Kiekhaefer engines.
OMC: 16:1 for 1965 and 1966 models. 24:1 for later OMC engines. JLO and Kohler engines use 20:1
Phantom: 20:1
Polaris: 40:1 on all Fuji - Polaris engines. 20:1 all others.
Poloron: 20:1
Raider: CCW or Hirth, 20:1 Regular gas. Kohler, 40:1 Premium gas.
Roll-O-Flex: 20:1
Rupp: 20:1 Xenoah engines use 30:1
Sabre: 20:1
Safari: 20:1
Scorpion: 20:1 Regular gas. Do not use outboard oil. 1973 and later, use premium fuel.
Sears: 20:1 . Regualar gas.
Ski-Bee: 20:1 Regualar gas. Do not use outboard oil.
Ski-daddler: 20:1. Lloyd engines use 40:1
Ski-Doo:1962-1972, use 20:1. 1973 on use 20:1 or 50:1 full synthetic.
Ski-Jet: 20:1
Skiroule: 20:1. Regular gas.
Ski Whiz: 20:1. Regualar gas.
Ski Zoom: 25:1. Premium fuel.
Sno Cub: 20:1
Sno-Flite: 20:1
Sno Ghia: 20:1
Sno Jet: 1966 tp 1972 use 25:1. Regualar gas. 1973 on, use 20:1 premium fuel for Yamaha motors and regular gas for Hirth.
Sno-Pac: 20:1
Sno-Pony: 25:1. Regualar gas.
Sno-Prince: 20:1 for JLO. 25:1 for Hirth and Sachs. 40:1 for Lloyd. Regualar gas.
Snow Birdie: 20:1
Snow Bug: 20:1
Snow Cat: 20:1
Snow Flake: 20:1 . Regular gas.
Starcraft: 20:1 for Kohler. 25:1 for all others. Regular gas.
Suzuki: 20:1. Regular gas.
Trade Winds: 20:1
Trans-Ski: 20:1 . Regular gas.
Viking: 20:1
Wildcat: 20:1
Yamaha: 20:1 . Regular gas.
Yukon King: (may bring Johnny Skeptical to mind) 40:1 for Lloyd. 20:1 for JLO.
NO SPARK: This is generally caused by a coil that has failed. Remove the coil and have it tested, or replace it. They don't cost much. The CDI box, if equipped, can also fail, and is rather expensive. Check the plug wires. Twist the plug caps to make sure they are tight. Take a look at the points, make sure they open and close, and are not pitted. Are you using the correct plugs?
FLOODING: This happens from either an ignition system that is not working correctly or, and generally always, from a problem with a stuck float or inlest needle in the carb.
