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Can a Snowmobile Engine Run Backwards?

Can a Snowmobile Engine Run Backwards?

For a long time after Joseph Bombardier tested the first snowmobile, riders experienced difficulties running the machines backward. Manufacturers resisted calls to create snowmobiles that could run backward efficiently until the late 1990s when Ski-Doo pioneered the technology snowmobiles use to move backward. 

You can run a snowmobile engine backwards mechanically or electronically. Pulling a lever engages mechanical reverse on older-version and 4-stroke snowmobiles. Newer snowmobiles have electronic reverse systems riders can initiate by pushing a button. 

This article looks at the two ways you can run a snowmobile engine backward. I’ll also tell you how to run a snowmobile without a reverse system backward. 

How To Run a Snowmobile Engine Backwards

The reverse feature on a snowmobile can save you a lot of time and effort, especially if you get stuck. The alternative to reversing is hopping off and manually pointing the snowmobile in the right direction — which is no easy feat in the freezing snow. 

You can run a snowmobile engine backward by mechanically or electronically switching it into reverse, depending on the system fitted on your snowmobile. 

Mechanical Reverse Systems 

The first reverse systems installed on snowmobiles were mechanical. It requires mechanical effort (often through pulling a lever) to run the engine backward. Pulling the lever places and locks the gears in reverse, moving the snowmobile backward. This system primarily exists in older and 4-stroke snowmobiles (source).

Snowmobiles — especially older cheap versions — were quite heavy, and adding a mechanical reverse system made them heavier. The extra weight compromised fuel efficiency, handling, and braking. 

The drawbacks of the mechanical reverse system inspired engineers to look for practical and cost-effective solutions. Bombardier started the development of a light reversing system for snowmobiles in the 1980s. 

Electronic Reverse Systems

The breakthrough for Bombardier came in the late 1990s when they became the first snowmobile manufacturer to install electronic reverse systems. The system, dubbed Rotax Electronic Reverse, first appeared in Ski-Doo Tundra R and Touring SLE (source). 

Several years later, Polaris introduced the Polaris Electric Reverse Control (PERC). 

Rotax Electronic Reverse

Creating the first electronic reverse system for snowmobiles was no easy feat. Bombardier needed to develop a reversing system and a driven pulley to handle reverse torque input. Furthermore, the system needed integration with computing power to ensure it came on at the right time and wouldn’t ignite even when activated by the rider at certain engine RPMs. 

Bombardier called the finished product Rotax Electronic Reverse (RER). The rider initiates the system by pushing a button on the handlebars. It slows the engine down to a specific RPM before firing the ignition at a preset point. The considerable force coupled with the position of the piston pushes it towards the other direction, initiating reverse. 

The engine continues operating as normal but in the opposite direction. A two-stroke engine can run in any direction due to the lack of mechanically driven valves (source).

The system refuses to activate RER at engine speeds of over 3,500 RPM. Therefore, you cannot use the reverse system to slow down a snowmobile. 

Switching an engine into reverse at high gear is quite risky, as it may lead to an accident or destroy the transmission system. 

Besides safety, the engine can’t shift to reverse at high speeds as it needs to get the timing of the ignition right to alter the crank shaft’s direction. You should only press the reverse button when the snowmobile is idling at less than 1,000 RPM. 

The system will slow the engine to around 500 RPM before timing the ignition at just the right moment to run the engine backward. 

Avoid throttling when reversing as it might prove dangerous. If the engine exceeds a certain RPM when reversing, the engine loses power automatically. 

A light shows when reverse is engaged. Some snowmobile models also play a sound when in reverse. 

To re-engage forward motion, slow the snowmobile and press the reverse button again. The engine will slow and reignite in the forward direction. The reverse light will switch off, indicating that the snowmobile has activated forward motion. 

Polaris Electric Reverse Control (PERC)

The RER system in Ski-Doo snowmobiles was initially treated with skepticism, as the revolutionary light-weight reversing system was expected to have faults. However, the RER system passed reliability tests and was swiftly adopted by other snowmobile manufacturers, including Polaris. 

Eventually, Polaris rolled out its own system dubbed Polaris Electric Reverse Control several years later, which wasn’t much different from Ski-Doo’s RER. 

In other industries, Polaris’ development of a similar system to Ski-Doo’s might have raised intellectual property concerns. However, snowmobile manufacturers often share patents, including Ski-Doo and Polaris. 

Ski-Doo and Polaris came to some sort of patent agreement, allowing Polaris to develop a system based on RER. 

Polaris didn’t improve RER much, and as such, PERC and RER operate similarly. There are slight differences (for example, PERC ignites rotation at a lower RPM) but the mechanics of both systems are essentially similar. 

PERC activates at the press of a button, running the engine backward. The same button activates the engine’s forward motion. 

Installing a Reverse System on a Snowmobile

Some older snowmobiles have no reverse systems, but manufacturing companies have created systems you can retrofit on the snowmobile. 

The electronic reverse systems are available on the internet at affordable prices. Furthermore, they’re easy to install. 

The installation process generally follows the steps below: 

  1. Remove the snowmobile’s ignition system controller, also known as the CDI box. 
  2. Replace the stock CDI with the custom CDI of the electronic reversal system. 
  3. Install the reverse button in a convenient location on the handlebars. 
  4. Connect the reverse button to the new CDI box. 

The simple procedure adds the reverse function to your beloved snowmobile. (source)

Conclusion

You can run a snowmobile engine backward, either mechanically or electronically, depending on the reverse system installed on the snowmobile. Older and 4-stroke snowmobiles often have heavy mechanical reverse systems that require more effort to activate. 

Newer snowmobiles have a reverse button that activates the electronic reversal system. The RER and PERC systems on most automobiles operate the same way and require the snowmobile engine to be idling for them to work. 

You can install electronic reversal systems on snowmobiles if there’s one available.

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