horsepower and 12 percent more torque than the baseline 850 Patriot engine, which we did not test for this comparison. It also has a lighter crank and flywheel than the standard 850, which provides better inertia and lighter handling. The Patriot 9R features the factory mod hefty bore of 88mm and stroke of 74mm totaling 899cc of fast-revving displacement. The ceramic-coated pistons also come from the racing world, and it’ s ported like engines used in the mod classes for more flow and power.
Polaris custom-builds its deep-lug tracks. It uses the Series 8 all-purpose, versatile 15- by 155- by 2.75-inch track with a weight-saving 3.5-inch pitch between lugs. The track comes in at 44 pounds.
The Khaos package delivers the Walker Evans Racing Velocity Hi-Lo front shocks at front, center and rear for the RMK Khaos rear skid on 16 inches of travel.
The 9R tips the scale at 426 pounds dry. It sells for $ 20,549.
If the Patriot 9R is the nimble running back, the Patriot Boost is an aggressive tight end. It’ s geared with the power to do what needs to be done— especially in deep snow— though at the expense of more weight.
The 850 Patriot engine with turbo has hillclimb competition cred, as well as snocross-developed technology in the throttle body injection. The Boost ProRMK rocks the 85mm bore with 74mm stroke displacing 840cc force fed by the vertically designed scalloped, reverse rotating turbine controlled by the SmartBoost System. It offers 50 percent more power at 10,000 feet than the standard, naturally aspirated 850.
Being a ProRMK, the Walker Evans Racing standard Velocity shocks are found throughout the sled. The ProRMK rear suspension actuates 16 inches.
The Boost has a purpose-built Series 9 15- by 155- by 3.25-inch track for ultra-deep snow. The lugs are more flexible at the top for better lift. It’ s not a trail track, and it even has a 50-mph speed limit for any trail usage— a warning on the dash will let riders know to dial back.
The Boost weighs in at 453.5 pounds. It sells for $ 22,250.
ENGAGEMENT
The throttle-to-track response is so instant that you can braap and brake and adjust and zoom quickly, especially in non-ideal bouncy snow conditions.
ENGINE ⊲
The updates to reduce weight and improve reliability make the RMK set ideal. The feeling of lightweight power is enjoyable whether you’ re jumping or climbing or getting onto an edge.
BUMPER ⊲
The little wings on the little front bumper set it apart but won’ t offer full protection, especially for the fasteners that attach the side panels to the hood.
TRACK ⊲
The 2.75-inch track is a really good shoe that moves the sled up and forward. If you spend even 25 percent of the time in mixed snow, the 2.75 is worth a look.
MOUNTAINSIDE CHATTER Polaris 9R RMK Khaos 155 Limited Edition 275
FEBRUARY 2026 / SNOWGOER. COM / 19