For the past 15 years or so, most sled manufacturers had reverse available for at least some models of their sleds. While some of the more deluxe or touring models came with reverse, others required it to be added as an option later.

Having reverse on a sled is a beautiful thing. You should be saving your energy for riding your sled, not spending it pulling your ride from the trailer or the garage. If you've never had a sled with reverse you don't know what you're missing. It may sound like a bad cliche, but once you have it you will never go back. When I got an opportunity to add reverse to my ride I jumped at the chance.

The Basics:
Reverse comes in two forms on a sled - mechanical and electronic.

Mechanical reverse is exactly as it sounds. There is a mechanism that you engage and then a bunch of gears re-align themselves, lock in position, and the track will spin backwards. As the system has been around a long time, it's quite reliable. Almost any snowmobile prior to 1998 uses this type of reverse and any 4-stroke sled on the market today continues to use this type of reverse. In addition Arctic Cat and Yamaha continue to use it on all their sleds. The only downfall to this system is the extra weight that it adds.

Around 1998 Ski-Doo released a new feature called RER (Rotax Electronic Reverse) and Polaris followed a few years later with PERC (Polaris Electronic Reverse Control). Electronic Reverse the engine rotation in conjunction with the computer that controls your snowmobile ignition system. When the user hits the reverse button it slows the motor to a near stop, and then does some magic with the spark plug timing, forcing the motor to flip to spinning in a reverse direction. The only way that someone knows that the sled is in reverse is the reverse light on the dash, though on some models it's accompanied by an audible back up alarm. You hit the gas and back up out of the garage/trailer or whatever hole you've dug yourself into. A second push of the button will slow the engine and flip it back into the forward direction again. The advantage of this system is that it does not carry the same weight and complexity of the Mechanical reverse.

It is worth noting though that sleds that use the RER/PERC use some different parts than those that do not. For example the secondary clutch, CDI, and an oil pump that will run in the reverse direction.

My 2003 ProX didn't come with Electronic Reverse, but I noticed that when I got it that Polaris had an option kit for the sled to add electronic reverse. I started keeping my eye on eBay as I could compare the parts list from a 2004 ProX (which comes with PERC) to my 2003 sled. From that part list I found three major pieces: CDI, wiring harness and a button to activate the electronic reverse. Polaris does make kits for 2003 and some 2004 sleds, with the average kit price being around $500. These kits are also available for other models and depending on the sled model, more or less may be included in the kit. For more details check out http://www.purepolaris.com/Detail.aspx?ItemID=2874616.

Installing the kit was fairly simple. I removed the stock CDI with the two mounting bolts that held it on the airbox and the installed the new CDI.

Next I replaced the wiring harness that connected the CDI to the main wiring harness that came up from under the motor. The last item was to connect the PERC button to the CDI (I used the little red button from the Polaris Dragon system). The PERC is activated by connecting one wire from the CDI to ground which was handled easily.

It works perfectly.  I start the sled, let it come up to temperature and hit the button. You'll hear the motor spin down, hesitate and then spin back up again.

1. It definitely works best once the motor has come up to temperature. If you hit the reverse button when it's cold, the motor will spin down and then stall out. Leaving the choke on when it's cold seems to help out some.
2. It's easy to burn (smoke) the belt first thing in the morning when then sled is cold. Be sure to warm the sled up, lift the rear end of the sled and spin the track a bit before trying to drive in reverse.
3. On a Ski_Doo sled, the RER button is always active. If you're running down a trail at 30 mph and your three-year old riding with you happens to put his hand on the RER button, the motor will dye out and start up in reverse. This has happened to at least one of my riding buddies. On a Polaris sled if the motor is about 4000 RPM it ignores the PERC button so it's not an issue.
4. On a Polaris, track tension is key. I like to run my track really loose on my sleds, but when you do this the rear suspension will lower down a bit. When you put it in reverse, this tends to suck the mud flap under the track and then your sled won't go anywhere. If you have studs in your track you've also just shredded the flap. If you run your sled with the manufacturer's recommended track tension this isn't as much of a problem (but you can still run into the problem if you backup against a snow bank). If you run your track loose, try standing up and leaning forward a bit over the handlebars and this will probably alleviate the problem

Reverse is a beautiful thing that I personally think everyone should have, and thanks to kits made available for our rides it might be possible for you to add it to your ride as well.