A Look at Snowmobile Exhaust Power Valves

Mounted in the exhaust port of certain snowmobile models, exhaust power valves are devices designed to improve combustion efficiency at varying RPM. Improved efficiency increases horsepower and lowers exhaust emissions.

At low RPM the valves are in a closed position, allowing for more efficient combustion and minimizing the levels of unburned gases escaping down the exhaust port. At high RPM the valves are in an open position, allowing the motor to breathe more freely and improving the scavenging effect needed for efficient performance in two-cycle motors.

Because exhaust power valves are located in the direct stream of exhaust flow, deposits consisting of soot, carbon and ash quickly accumulate, requiring the valves to be cleaned regularly. If they are not cleaned, they may get stuck, and operators will notice a considerable power loss and/or bog-type operation. Exhaust power valve with deposit build-up Clean exhaust power valve In some instances, deposit build-up may be worse than others.

There are several reasons for this:

The machine may be consuming more oil than is needed. Oil injection pumps vary the amount of oil injected based on the throttle position. As the throttle is opened, oil consumption increases. AMSOIL 2-Cycle Oils are recommended for use at 50:1 mix ratios, but if the sled is consuming more than one quart of oil per 12 gallons of gas, it is exceeding an average mix ratio of 50:1. The less oil the sled burns, the fewer the deposits that accumulate on the exhaust power valves. If you wish to have a sleds oil injection pump setting checked, AMSOIL recommends bringing it to a local dealership so a qualified snowmobile mechanic can make the correct adjustments.

Another contributing factor to excessive deposit build-up is riding style. Snowmobiles operated at low speeds and/or steady RPM for extended periods of time will accumulate deposits more quickly than snowmobiles operated at higher speeds. Two-cycle motors do not operate at maximum efficiency at slower speeds, causing a large percentage of unburned fuel and oil to exit through the exhaust. This unburned material accumulates on exhaust valves and forms deposits. Also, since snowmobiles operated at low-level constant RPM do not frequently actuate the valve, it allows deposits to form more rapidly, requiring more frequent valve maintenance.

Snowmobiles run at higher RPM operate more efficiently and can extend time between valve cleanings. Efficient operation results in increased combustion temperatures and more complete burning of the oil/fuel charge. Higher RPM also means the exhaust power valve is more frequently actuated, disrupting deposits and slowing down their accumulation.

Finally, the type of two-cycle oil used in a snowmobile can improve valve cleanliness and extend maintenance. Because they effectively fight deposit formation, AMSOIL Synthetic 2-Cycle Oils exhibit better overall performance than petroleum two-cycle oils. AMSOIL Synthetic 2-Cycle Oils also resist friction and heat more effectively, burn cleaner and can safely be used at 50:1 mix ratios.

Routine maintenance is important for snowmobiles equipped with exhaust power valves. However, maintenance can be eased through the following:

• Extending time between cleanings through the use of AMSOIL 2-Cycle Oils
• Monitoring and adjusting oil consumption as needed
• Cleaning the valves before they get stuck to allow for easier removal
• Using AMSOIL Power Foam to loosen the deposits
  
   

HP Injector: Superior performance in DFI outboard motors. Prevents piston and combustion
chamber deposits. Also prevents “ring jacking”
common to DFI outboards. Low smoke, low odor product. Contains up to 30 percent more additives for “super clean” operation. Prevents wear for long engine life. Prevents rust. Multi-functional and
recommended for use in many two-cycle motors. Low aquatic toxicity. Recommended for use as
injection oil or at a 50:1 pre-mix.

Interceptor: Excellent exhaust power valve performance. Low smoke and odor. Surpasses SAE #4 cold temperature fluidity properties and has a -50°F pour point. Prevents wear on cylinders and bearings for long engine life. Prevents pre-detonation by controlling ignition promoting
deposits called “hot spots”. Versatile and excellent for all types of recreational equipment. Protects against rust. Recommended for injector systems or at 50:1 mix ratios

Dominator: Provides excellent film strength for high heat, high RPM motors, reduces friction for maximum power. Recommended for use with coated or non-coated racing pistons, and for use with exhaust power valves. Recommended for use with high octane racing gas. Burns clean, prevents ring sticking and plug fouling. Provides excellent protection at 50:1 pre-mix or in injection systems.

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World Champ Gets Season Title

Wanderscheid wins WPSA points races
Beausejour, Manitoba ~ PJ Wanderscheid needed a good, but not a great, weekend of racing in Beausejour, Manitoba to wrap up his second straight championship season. The Sauk Centre, Minn.-native doesn’t normally run well in Beausejour, but the weekend was more of a big picture focus for the three-time Eagle River World Champion.

The track in Beausejour is the biggest oval track Wanderscheid races each year. It doesn’t offer much in the way of banking, but it is fast. To add to the challenges, Wanderscheid also had to compete with a bigger field as the Eastern Pro Tour had the weekend off from racing and many of the big-name racers from the U.S. and Canada showed up in Manitoba for the WPSA event.

The race sported two Pro 600 finals on Saturday, with one of the races being a make-good for the missed WPSA Flip Merwin race earlier this year. Wanderscheid started his first final with a poor holeshot, but good top end speed. The big track allowed everyone to be fast, and Wanderscheid settled for fifth place finish.

The second final also brought a less then expected start from the young rider. Being behind the race leaders was again a disadvantage in the Pro 600 final, as Wanderscheid had to settle for a sixth in the second race of the day.

Sunday the focus switched to the Champ 440 class. Again the team had to find a way to create hole shot power without sacrificing straight away speed. In the final, they couldn’t find the balance and settled for a sixth place finish.

With the top 10 finishes in both classes, the Team AMSOIL rider was able to capture the season long points championships in both the Pro Formula and Pro Champ classes in the WPSA Ice Oval Association. In 2005, Wanderscheid won the United States Snowmobile Association’s Oval Ice Series championship and is a three-time winner of the Eagle River Snowmobile Derby.

"We continue to make good strides in Beausejour,” said Wanderscheid. ”We started a few years ago when trip to Canada meant a long weekend of racing and breakdowns. Starting this year, we are putting together sleds that will generate the speeds that are needed at this big straightaway oval. It was great to finish first in points in the top two categories in WPSA this year. Wanderscheid racing was able to have another great year because of crew’s dedication, our sponsor’s great support, and the fans that come out and support us every week. Thank you everyone.”

Beausejour, Manitoba was Wanderscheid’s last race of the season. He will be in attendance at the second annual Arctic Cat Snow Blast in West Yellowstone, Mont., this weekend.

Eckstrom Closes Gap In Points Race

Duluth rider closing in on Pro Open Championship
Green Bay, Wis., ~ Team AMSOIL snocross rider D.J. Eckstrom barely missed winning two World PowerSports Association championships in 2005. The Duluth, Minn.-rider is making a late season run at the Pro Open title in 2006.

Eckstrom, and Team AMSOIL teammate Carl Schubitzke, made the trip to Green Bay, Wis. last weekend to take part in the third annual Lambeau Leap. A large crowd turned out at the historic Lambeau Field for the eighth round of professional snocross racing.

Eckstrom, who has three podiums in the Pro Open class this season, including the win at the AMSOIL Duluth National, won his first qualifying heat and qualified on the front row for the 24-lap main event. Eckstrom was running in second with two laps to go when a bobble threw off his rhythm, allowing two riders to pass him. Eckstrom finished in fourth in the final and sits in the fourth position for the season points race. He trails leader Robbie Malinoski by just 29 points and is only four points behind third place rider Dave Allard.

In Pro Stock, a mid-air collision in Eckstrom’s third heat forced him to the Last Chance Qualifier to make the final. After finishing in the final transfer spot, Eckstrom faced a tight track inside Lambeau Field. He would finish 11th in the final. Eckstrom is currently in seventh in the Pro Stock class.

Schubitzke, meanwhile, had a bad crash in his first race of the day. He hit a deep hole in the first round of Pro Stock qualifying, ramming his chest into his handlebars. He was able to race all day, but was unable to make the finals in both classes. Tests revealed a cracked rib and broken bone in his hand. Schubitzke is undergoing more tests this week to determine his availability for the remainder of the season.