Exhaust power valves automatically vary the exhaust-port opening so your sled can provide good low-rpm throttle response and maximum top-end power. Their placement in the path of exhaust gases over 1,000°F (538°C), however, means hard carbon deposits can form, causing them to stick, reducing engine power and performance. Using a high-quality, clean-burning two-stroke oil helps prevent sticking. So does cleaning them seasonally. Here’s how to clean snowmobile power valves.
Step-by-Step: How to Clean Snowmobile Power Valves
Tools you need:
- Razor blade
- Soft-bristle brush (optional)
- Latex gloves
- Carburetor cleaner or similar cleaner, like AMSOIL Power Foam®
Remove the power valves
We’re using an engine from a Ski-Doo 800 P-TEK we had available in the AMSOIL mechanical lab for this demonstration, but the basic steps will apply to most snowmobile makes and models.
Remove the plastic covers from the exhaust power valves. They’re typically held on with just two bolts.
Now, remove the two bolts that hold the power valve assembly into the cylinder head.
With the exhaust bellows exposed, unthread it by hand and set it aside. Take care not to lose the springs that hold the barrel-shaped side valves in place.
Slide the power valve out of the slot in the cylinder head. Again, take care to avoid dropping parts. If there are excessive deposits, you may have to work it back and forth to loosen and free it from the engine. Set the power valve on a rag.
Scrape away carbon deposits
As already said, the power valves sit in the scalding-hot exhaust stream, meaning they’re prone to collecting carbon deposits, especially if you’re using a low-quality two-stroke oil that doesn’t burn cleanly.
Deposits can cause the valves to stick open or closed, which reduces engine power and performance.
Using a razor blade, carefully scrape off carbon deposits. Be careful to avoid gouging the metal.
Use carburetor cleaner
Once you’ve removed the thick deposits, spray carburetor cleaner or a similar product designed to remove deposits, like AMSOIL Power Foam,® on the valves and let them sit for 10-15 minutes. This will help soften the remaining deposits so you can remove them easier.
Use a rag or soft-bristled brush to clean the valve components. Spray another coat of cleaner on them if needed and let them sit. If they’re really dirty, soak them overnight.
Reinstall the power valves
Once clean, reinstall the power valves in the cylinder head, thread the exhaust bellows back on and apply the cover. That’s all there is to cleaning snowmobile power valves.
How often should I clean snowmobile power valves?
Most manufacturers recommend cleaning seasonally, but check your owner’s manual for the specific recommendations for your sled.
If your sled begins to run poorly and lack power, dirty power valves could be the culprit. It’s a relatively easy and cheap fix, so start there before trailering your sled to the dealership and dropping a bunch of money.
Clean them in the spring before storage. This prevents carbon from solidifying over the summer and becoming even more difficult to remove.
Use a good two-stroke oil to keep power valves clean
Prevention is the best maintenance practice, so use a high-quality synthetic two-stroke oil, like AMSOIL INTERCEPTOR® Synthetic 2-Stroke Oil, that burns cleanly and resists high-heat deposits. It will help prevent the power valves from collecting deposits and sticking, maximizing power and reducing maintenance.
To demonstrate its performance, we put INTERCEPTOR to the test in a rental Polaris RMK 800 used for a full season in the Canadian Rockies. After a season of abuse, the oil protected the engine and prevented the power valves from sticking.
Check out the full test in the video below.