I picked up the SG Demo Yamaha SR Viper M-TX 153 LE smack dab in the middle of December. This was perfect timing as the mountains near where I live in Bozeman, Montana, were getting pounded with fresh snow, amounting to handlebar-deep snow during weekend ride excursions. Having never spent a full season aboard a four-stroke mountain sled, I was eager to get out a see what it could do with the reliable 1049cc three-cylinder Yamaha engine, 15- by 153- by 3-inch Power Claw track and Fox FLOAT 3 Evol shocks.
With the M-TX being equipped with electric start, it’s pleasant not having to pull the rope every time I want to fire up the sled – something I’ve never been privy to in all my years. The thermometer showed the air was minus 16 degrees F in the first few mornings I rode it, but that was no problem for the Viper. It quickly fired up.
Bombing up the ungroomed trail through wide moguls kept the sled at a fairly level attitude with the as-delivered shock settings tracking mostly straight and riding comfortably. Just for grins to try it out on one of those cold mornings, the seat heater did prove to be a welcome feature! Once into the backcountry where the snow got deep, it was a tough day to break-in this new steed as I was breaking trail through the powder, and that required more throttle than one would like per the owner’s manual, but ol’ Blue handled everything without skipping a beat.
Even in the deepest of snow, the sled encourages a rider to putt along as the engine is powerfully grunty, the track hooks up without spinning and I feel relatively on top of the snow and in control of whatever may happen. The classic Arctic Cat bars and grips – remember, this is a shared platform between Arctic Cat and Yamaha – are familiar to my hands with the ergonomics feeling natural on the flats, climbs, trails or when boondocking through the woods.
Along with those ergos, the narrow ski stance and construction keeps the sled feeling nimble and easy to lay over – almost too easy sometimes. Perhaps due to the shorter 153-inch track, the machine tended to high-center on the side panel when I laid it over while carving, leaving the track up in the air.
Now with over 200 miles on the trusty Yamaha, I’ll start working with shock air pressure settings and ski placement – this Viper’s stance can be widened or narrowed 2 inches from the stock centered position. My only gripe so far is that the handlebars or ski alignment have come loose – or the steering arm is out of adjustment leaving the skis turned while the bars are straight. This may be due to slop in the upper U-joint.
Also the sticker on the Evol shocks appears to be upside down, indicating the Evol chamber’s valve is up near the shock mount, and the main chamber’s valve is down at the end of the small chamber, leaving me scratching my head and wondering if maybe Fox changed something. Following the directions to fill the Evol chamber (as indicated) first doesn’t work with the pump and gauge, so I will try filling the main chamber first.