If your sled is acting up, learning how to clean snowmobile carbs is the best way to save your weekend from being a total bust. There is nothing more frustrating than pulling the cord twenty times only to have the engine sputter and die, or worse, having it bog down just as you're trying to climb a hill. Most of the time, the culprit isn't a blown motor or a dead ignition; it's just gunked-up fuel that turned into a sticky varnish over the summer.
Carburetor maintenance is a rite of passage for any sled owner. Modern fuel, especially the stuff with ethanol in it, doesn't like to sit around. It breaks down, leaves behind a crusty residue, and plugs up the tiny passages that your engine relies on to breathe. In this article, we're going to walk through the process of getting those carbs spotless so you can spend more time riding and less time swearing at your machine in the garage.
Getting your workspace ready
Before you even touch a wrench, you need a clean place to work. Carburetors are full of tiny, delicate parts that love to bounce off the floor and disappear into the dark corners of your shop. I usually like to lay out a clean rag or some white paper towels on a workbench. This makes it much easier to see those tiny jets and pins when you set them down.
You're going to need a few basic tools: a set of screwdrivers (specifically a good-fitting Phillips and a small flathead), some needle-nose pliers, and a can or two of high-quality carb cleaner. If you have access to compressed air, that's even better. Oh, and don't forget a small container to catch the leftover gas that's definitely going to leak out when you pull the bowls off.
Removing the carbs from the sled
The hardest part for some people is actually getting the carbs out of the engine bay. Depending on your model, things can get pretty cramped in there. You'll start by removing the airbox or the intake filters. Once those are out of the way, you'll see the carburetors held onto the engine by rubber boots.
Loosen the clamps on those boots, but don't take them all the way off—just enough so the carbs can slide out. You'll also need to disconnect the throttle cable, the choke (or enricher) cables, and the fuel lines. A little tip here: take a photo with your phone before you disconnect anything. It's incredibly easy to forget exactly how those lines were routed, and a quick picture will save you a massive headache later.
Tearing down the carburetor
Now that you have the carb on your bench, it's time to see what's going on inside. Start by flipping it over and removing the four screws holding the float bowl (the bottom cover) in place. If the screws are stuck, don't force them and strip the heads. Give them a light tap with a screwdriver handle to shock the threads loose.
Once the bowl is off, you'll likely see some green or yellowish gunk. That's the "varnish" we talked about. This is what's choking your engine. Carefully pull the pin that holds the float in place and lift the float out. Watch out for the needle valve—it's a tiny little piece that sits under the float arm. If the rubber tip on that needle is cracked or has a ring worn into it, you'll need to replace it, or your carb will leak fuel everywhere.
The secret to a real clean: The Jets
This is the most important part of the whole process. Inside the carb body, you'll find the main jet and the pilot jet. The pilot jet is usually the one that causes the most trouble because its opening is about the size of a human hair. If your sled won't idle or dies as soon as you give it gas, the pilot jet is almost certainly clogged.
Unscrew the jets and soak them in carb cleaner. Some people like to use a thin piece of wire to poke through the holes, but you have to be extremely careful. Most jets are made of soft brass, and if you scratch the inside or make the hole bigger, you'll ruin the air-fuel mixture. I prefer to use plenty of spray cleaner and then blow them out with compressed air. If you can't see a perfectly round circle of light when you hold the jet up to a lamp, it's still dirty.
Cleaning the carb body and passages
While the jets are soaking, grab your can of carb cleaner and start spraying out all the little holes and passages in the main carburetor body. You should see the cleaner shoot out of another hole somewhere else—that tells you the passage is clear.
Pay close attention to the area where the needle valve sits and the throat of the carb where the slide moves up and down. If there's a lot of carbon buildup or dirt, use an old toothbrush to gently scrub it away. You want everything to be shiny and smooth. Once you're done spraying, use compressed air to blow out every single nook and cranny. This ensures no leftover liquid or bits of grit are hiding in there to cause trouble later.
Reassembling the parts
Putting it all back together is basically the reverse of what you just did, but there are a few things to watch for. When you put the jets back in, make sure they are snug, but don't over-tighten them. Brass is soft and easy to snap.
When you drop the needle valve and float back in, check the float height. If you accidentally bent the little metal tab while cleaning, your fuel level will be wrong. Most of the time, the float should sit level with the carb body when held upside down, but check your manual if you're unsure. Finally, make sure the gasket for the float bowl is sitting flat. If it looks stretched out or cracked, it's worth the five bucks to buy a new one so you don't end up with a fuel leak on your first ride.
Installing and syncing
Slide the carbs back into the rubber boots on the engine and tighten the clamps. Reattach your fuel lines, throttle cables, and choke cables. This is where those photos you took earlier come in handy!
If your sled has multiple cylinders, you might need to sync the carbs. This just means making sure both slides are opening at exactly the same time when you pull the throttle. A quick way to check this is to put your fingers inside the carb throats (with the engine off!) and feel if the slides move at the same moment. It's not as precise as using a vacuum gauge, but it'll get you in the ballpark.
Final thoughts on maintenance
Learning how to clean snowmobile carbs isn't just about fixing a problem; it's about preventative maintenance. To keep from having to do this every single year, try using a fuel stabilizer during the off-season, or better yet, run the engine dry before you put it away for the summer.
Once everything is buttoned up, give the primer a few pumps or pull the cord until the fuel reaches the carbs. It might take a minute to start since the bowls are empty, but once it fires up, you should notice a much smoother idle and a crisp response when you blip the throttle. There's a certain satisfaction in knowing you did the work yourself, and your sled will definitely thank you for it when you're out in the powder. Now, go grab your helmet and enjoy the ride!