You just bought your snowmobile earlier this year, so you’re still trying to develop a maintenance schedule. You know you need to clean your snowmobile carb especially, you’re just not sure how often. Should you aim for a monthly cleaning, every six months, or even longer?
You should clean your snowmobile carb at least every year, typically at the start of the snowmobiling season. If the carb is getting older or giving you trouble, you can clean it twice a year, as it may help.
In this article, we’ll tell you everything you need to know about snowmobile carb maintenance, from where to find the carb on your vehicle, how to clean it, and even some handy maintenance tips to follow. You won’t want to miss it, so keep reading!
What Is a Snowmobile Carb and Where Do You Find It?
First, let’s start with a small definition. A snowmobile carb is short for the carburetor. Many vehicles have carburetors besides your snowmobile, such as cars, trucks, and motorcycles.
Atmospheric pressure builds up within the carburetor, exerting 15 pounds per square inch (PSI) of pressure or more. When the carburetor’s atmospheric pressure and that of the engine changes, air and fuel can flow.
For example, by switching high pressure to lower pressure through atmospheric pressure, a two-stroke engine’s crankcase would house that low pressure, which decreases the carburetor’s pressure as well. Outside of the engine, the pressure is far higher than it is inside, which sends air into the engine to equalize the pressure. This air travels through your snowmobile’s carburetor, combining with fuel as it does.
If your snowmobile has a Mikuni carb, which is common, then here’s how that works. The carb includes four tuning circuits. The choke chamber allows the air and fuel mixture to become richer so even if the cold weather causes the fuel to evaporate some, you won’t lose much.
The needle jet, needle taper, and slide cutout opening all aide your acceleration, especially when you set the needle jet to a ¾ throttle midrange. If the throttle is ½ up, then your main jet circuit does most of the work.
Colder air has a higher density than warm air, so you may have to richen your fuel more often depending on the temperature. If the temperature decreases by 40 degrees Fahrenheit, for example, then your main jet at size 400 would have to go up to size 420. You’d also have to increase the main jet size numbers by 10 if your altitude increases by 2,000 feet. The higher the altitude, the thinner the air, so keep that in mind too.
Not all snowmobile carburetors will work exactly the same way, as the type of engine influences carb functioning. The above is a basic overview though that will help you understand this major component of your snowmobile a little bit better.
Speaking of understanding your carb, where on your snowmobile do you find it? Since it operates in conjunction with your engine, try checking your snowmobile’s hood to track down the carburetor.
While it will certainly differ by model, most carburetors are small, cylindrical metal objects with three or four tubed openings or tuning circuits at the top and sides, including one choke chamber. The carb will also have tubes protruding out of it, which are sometimes black and other times a pink translucent plastic.
How Do You Clean the Snowmobile Carb?
You know from earlier that you should clean your snowmobile’s carb about annually, maybe twice a year, but you have no idea how to go about doing it. Here are some steps you can follow for most snowmobile models.
These steps should apply whether you have an older round-slide carb, an un-racked one, or the newer rack twin cylinder flat-side carb, as the technology hasn’t changed much from one type of carb to another.
Step 1: Before you can clean the carburetor, you need it out of your snowmobile. This is one of the most difficult steps of the whole process, but it’s worth doing. Cleaning the carb within the snowmobile will cause you to miss certain areas.
To take the carb out, start by removing your air box. This will give you greater access to the carb. Clamps on either side of the carburetor must be undone, and then you can free the carb and any intake boots.
If you have more than one carb in your snowmobile, separate the fuel line between them.
Step 2: You may see a few more cables around your carb. These are the choke and the throttle. You can’t leave these on either. If you have needle-nose pliers handy, then point them at the cable’s e-clip to loosen it. You can then unfurl the cable all the way.
The cable will still be attached to a mount at this point. Leave the top lock nut in place as you dismount the cables if possible, unless you can easily readjust your cables later.
Step 3: Next, you want to detach your carburetor float bowls. If you have a Mikuni carb, then look for a corner screw that will let you get to the center bowl nut while keeping the float body intact if you change your main jet.
If you need to take the carb float bowl out entirely since you haven’t cleaned it in a while, then start by removing the center nut, as that should let you remove the bowl with ease.
Step 4: Now you can see all the carb’s internal components, such as the jets. It’s best to take these off rather than clean them where they are. The pilot jet handles your snowmobile’s idle circuit. With the carb float bowl gone, you should be able to easily find the pilot jet.
Check the main body of your carb, where you should see a tube. Beneath the tube is your main pilot. A screwdriver is all you need to get the jet out, but don’t keep screwing or unscrewing. A stripped jet almost never comes out again.
Step 5: With your pilot jet taken care of, next, move on to the main jet. Look to the middle of your carb and you should see this jet. You’ll need a nut driver or a six-millimeter socket instead of a screwdriver for the removal job, except for some Polaris snowmobiles where a screwdriver suffices. If you see a washer beneath the jet, keep this for later, as you will need it again.
Step 6: The float bowl’s seat assembly and needle need to come out now. If yours is a rack carburetor, look for a plastic assembly. Most of these are held together by Phillips screws. Your trusty screwdriver can loosen these screws.
Step 7: No, you’re still not done. Well, you are with detaching all the carb’s internal parts, but not the external ones. Start with the fuel screw, which has a white handle. Make sure as you use your screwdriver to do this that you don’t unscrew without counting the rotations. Otherwise, you won’t know how many times to screw the fuel screw back in. That will make reattaching everything later a big headache.
Step 8: Under the top cover plate is the jet needle. You can use a screwdriver or another tool for unbolting your top cover plate. Then, switch to an Allen wrench for the jet needle, as you need to grab a hook and loosen it up. By then twisting the hook, the needle should come out with no difficulties.
Make sure you don’t misplace the damping shim either, which is beneath the needle’s e-clip.
Step 9: Okay, so you’ve opened all your carb ports and taken out the jets. You’re ready to begin cleaning! We recommend relying on high-pressure air for this job, as you’ll get better results. Make sure you clean the jets primarily with the air.
You do want to buy some carburetor cleaner for soaking the carb ports, then use the air pressure to clean the parts you missed. Gumout is a popular carb cleaner that can reduce high exhaust emissions, stalling, hard idling, and rough starts. It removes dirt, varnish, and gum not only from the carbs, but the choke valves as well.
If you find any of your jets are in poor shape over time, you may pay around $7 each for a new one. If they’ve corroded and soaking them in Gumout or another carb cleaner doesn’t work, then it’s time for a new jet. If it’s your seat assemblies or the needle that need to go, these are about $25 each to replace, so they’re a little more expensive.
Step 10: Everything is clean, so let’s put it back together. In the main body, replace your starter jets, the main jet, and the pilot jet. Make sure they’re reinstalled firmly but not so tight that you strip the jets.
Step 11: In the face place, add your bolt and main body seal, reattaching all four screws.
Step 12: Add your needle back where it belongs and then reattach its e-clip, making sure you don’t forget the needle’s washer as you do this.
Step 13: Put the carb nuts and bowls back and then the top cover plate.
Step 14: Reattach the air box, fuel line, and the throttle and choke cables.
Here’s a handy YouTube video showing you how it’s done for a Ski-Doo snowmobile. If you’re the visual type, this video may be useful.
Snowmobile Carb Maintenance Tips
We have a few tips that can help as you care for your snowmobile’s carburetor now and in the years to come.
- Write out a maintenance checklist. Your carb may be an important part of your snowmobile, but in that regard, it’s one of many. To ensure you don’t forget to clean or maintain any snowmobile parts, having a list is ideal.
- You can do snowmobile carb tune-ups more often than you clean the entire carb system. This isn’t a bad habit to get into, but it does require you have extensive knowledge of your carburetor.
- As we said before, always take out all parts of the carb rather than just spray carb cleaner on some exposed parts and call it a day. Now that you see what the carb system removal process is like, you know there’s no way you can clean every component that way.
- Invest in a quality carb cleaner. Gumout is one of these, but you don’t have to use it. You might ask your fellow snowmobilers what they use or go your own way, but don’t cheap out here.
- Don’t ignore parts of your carb that are in poor condition. Some of the parts are a little costly to replace, but a corroded jet or a bad needle could affect snowmobile performance. It’s not worth it.
Should You Switch to an Electronic Fuel Injection System?
If all this sounds like a lot of work, you can always use an electronic fuel injection system or EFI for your snowmobile. An EFI determines the amount of fuel the cylinders receive much more precisely than a carb system. This keeps your fuel volume more consistent.
Growing popular in the 20th century as motorists began driving longer distances, and then retaining popularity into the 21st century, the EFI has become standard in most cars produced after 1980. They’re also a staple in many newer snowmobile models.
An EFI works like this: a fuel pump allows fuel to pass through the fuel tank to the pump. The pump then sends the fuel through fuel lines until it reaches your engine. A fuel pressure regulator there allows only the necessary amount of fuel to reach the injectors, doing so via a mass airflow sensor.
The sensor tracks air volume in the engine and then uses an air to fuel ratio to determine fuel levels. The mass airflow sensor sends this information to the electronic control unit. Your fuel injectors then let the gas in.
Is EFI a better choice than a carb? Absolutely. It’s a lot newer and more technologically-driven. You don’t have to worry about elevation, humidity, or air temperature interrupting your snowmobile performance like you do with a carburetor. Also, you can skip the above time-consuming and sometimes messy cleaning.
Carbs are less expensive than an EFI, so you would need to have a sizable budget. Still, if you find yourself tired of cleaning your snowmobile carb year after year, it might be time to look into something different like an EFI.
Final Thoughts
A snowmobile carburetor combines fuel and air into the correct ratio for your engine. You should aim to clean your carb yearly, and make sure you take out all the components when you do.
Since cleaning the carb can be a lengthy process, some snowmobilers today favor electronic fuel injection systems or EFIs. No matter which you use, you now know how to maintain your snowmobile so it’s in better running condition!