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Premium Roll-Over Valve Kits for Arctic Cat King Cat and Yamaha Sidewinder

The Four Stroke Solutions LLC King Cat and Sidewinder ROV kit replaces the OEM normally closed check valve located in the oil tank breather line, with a normally open electric shut off valve.

Q, What is the difference between a normally closed and normally open valve?

A, "Normally" simply indicates the "at rest" or "non commanded" state of the valve. For example, a normally closed valve defaults or rests in the closed position. While a normally open valve defaults or rests in the open position.

Q, Which is better for a snowmobile breather (roll over) valve, normally open or closed?

A, It is our opinion that a normally open valve is better suited for a roll over valve on a snowmobile for several reasons.

Snowmobile dry sump breather systems can and do accumulate some moisture or condensation within the breather line/hoses. Usually this moisture will mix with oil vapors and form a milky White substance. This is considered normal and is a by-product of the combustion process as well as the heating/cooling effect from ambient moisture content and melting snow. Because snowmobiles are usually operated in below freezing temperatures this moisture accumulation may freeze. This is especially true if the snowmobile has been sitting outside in below freezing temperatures overnight.

When you start the engine in the morning and if the breather system is venting correctly, the warm air from the hot oil will quickly melt any accumulated moisture in the breather line.

By design a normally closed valve is spring loaded to close and requires air flow/pressure to open and start the venting process.

If there is enough moisture or milky sludge accumulation in the valve itself and the snowmobile has been sitting outside in below freezing temperatures, it is possible for a normally closed valve to freeze in the closed position. With a normally closed valve frozen shut, air cannot properly flow through the breather hose and thaw the frozen moisture as quickly. When the breather vent cannot flow air properly, pressure will build inside the oil tank which usually results in an oil leak at the oil tank halve seal.

When a normally open valve is used as a ROV, the default position is in the open position. Because a normally open valve is already in the venting mode, it does not have to change position when the engine is started in below freezing weather. This allows air to flow quickly and the warm air will thaw out any moisture in the breather line with no restriction!

Q, Will the factory OEM normally closed check valve allow oil to leak out, if the engine is still running while the snowmobile is on its side?

A, If the engine is still running while the sled is on it's side and under the right conditions it is possible. Anytime the engine is running, air flow is forcing the OEM check valve to open and oil can flow out of the breather hose. This is why we prefer to use a tether to control a normally open valve. 

By using a tether, it shuts down the engine and closes the shut off valve at the same time!

Q, Why can't just remove the OEM normally closed breather valve and install a bypass hose?

A, Actually you can and it has been successfully done by some owners who are trail riders.

However there is one primary drawback to this approach if you are a mountain or off trail rider.

With an open hose vent system there is very little to no roll over oil leak protection. While it's true that you can route the vent hose up high and back down again. Most snowmobile roll over's in the mountains or off trail do not evolve the sled being 180 degrees totally upside down. Instead the sled is usually laying on its side at some varying angle. Often times the vent hose may be at the "low point" and allow the oil to drain out, particularly if the engine is still running.

This is why the preferred method of preventing a roll over oil leak is a shut off valve. In other words, a valve "closes the door" to an oil leak as opposed to a "maze" that the oil can travel through!


All King Cat/Sidewinder Roll-Over Valve Kits are a top of the line premium kit that come standard with our Electronic Roll-Over Valve Control Module or ROVCM!

The ROVCMs are programmed to initially close the shut off valve at 16.4 to 16.7 volts. This increases the valve closing strength by approximately 170% when compared to straight battery voltage and allows the shut off valve to be the strongest and fastest closing roll over valve built to date!

During cold weather durability testing, we found that the shut off valve requires a higher closing voltage then normal battery voltage alone. The higher closing voltage that the ROVCM provides, allows the shut off valve to close much more consistently over a wider range of riding and 

temperature conditions.

For a detailed description of about the ROVCM please see our high performance ROVCM page at

Battery voltage monitoring:

The ROVCM has a battery voltage/auto shut down feature. For example if the rider pulls his/her snowmobile in to the trailer at the end of the day and uses the tether cord to shut the machine down, but forgets to turn the key off. The ROVCM will start monitoring the sled's battery voltage after approximately two hours of "on time". If the battery voltage drops to the programmed level, the ROVCM will automatically switch off the Roll-Over Valve system to help prevent discharging the battery.

On King Cat/Sidewinder snowmobiles, if the rider uses the handle bar kill switch the shut the engine down but forgets to shut the key off, there will still be a 23 milli-amp drain on the battery. This is because while the ignition key is in the "on" position and one of the snowmobile's relays is still being energized. Note, this is a normal condition and it's always best to turn off the engine using the key.

Note: because the gauge display is powered down the rider may not notice that he/she has left the ignition key in the "on" position.

A unique feature of the ROVCM battery voltage monitoring/auto shut down mode, is that it will also power down the snowmobile relay!

If the tether cord is pulled with the key left in the "on" position and the handle bar kill switch is pressed, the battery voltage monitoring/auto shut down feature will shut down both the Roll Over Valve system and the snowmobile relay to drop the battery draw to zero amps!

Engine oil pump re-priming mode:

The Quick Prime system is a fast, convenient way to re-prime the oil pump by simply pressing and holding a button!

If the snowmobile is laying of its side with engine still running, the oil pump can start to draw air due to the suction port in the oil tank being exposed to air. When this happens the low oil pressure switch may shut down the engine to help protect the engine. During this time the engine oil pump may have also lost its prime. When the rider gets the snowmobile back upright, he or she may find that the engine may not re-start or starts and shuts down within a few seconds due to no oil pressure.

All King Cat/Sidewinder Four Stroke Solutions LLC Roll-Over Valve kits are equipped with a ROVCM and we have developed programming specifically for the oil pump re-prime feature! During the re-prime modes the ROVCM commands the valve to close, which allows pressure to build in the oil tank and force engine oil to the engine oil pump for re-priming purposes.

Using the Quick-prime switch.    

To use the Quick-prime switch simply press and hold the Quick-prime switch down while starting the engine. Once the oil pressure light goes out on the gauge, release the Quick-prime switch. It's that simple, quick and easy to use !! Normally the oil pump will re-prime in about 2 seconds!

Hood removal quick release connector:

Sometimes it's the simple things that can make a difference!

King Cat/Sidewinder ROV kits are equipped with a four pin weather proof connector. The connector is located near the factory hood harness connector and provides a quick disconnect point in the main ROV harness. This allows for easier removal of the hood as well as making the Roll Over Valve kit easier to install!

Genuine OEM Arctic Cat tether switches:

Just like our other Roll-Over Valve kits, the King Cat/Sidewinder ROV kit comes standard with OEM Arctic Cat tether switches. The OEM Arctic Cat switch uses a brass center plunger, a rubber inner bellows seal and a cap center screw for years of reliable service.

Plug and Play installation:

King Cat/Sidewinder ROV kits are plug/play into the back of the ignition switch for easy installation. All Four Stroke Solutions Roll Over Valve kits include detailed installation instructions. Additionally we have detailed installation photos in our photo gallery pages as well!

Tether controlled:

Just like our other Roll-Over Valve kits, they are tether cord operated for simple operation!


Roll Over Valve kits are US patented under patent numbers 8,225,766 and 8,528,516.

Arctic Cat King Cat and Yamaha Sidewinder Premium Roll Over Valve Kit