2015-Up AXYS 860 Ultimate Big Bore Kit


Regular price $4,804.95

  • Big bore kit fits all 2015-Up AXYS 800 motors

  • Kit includes everything necessary to take your stock sled to an 860cc power monster

  • HUGE gains in horsepower and torque

  • 190 horsepower

  • 120 ft/lbs torque

  • Our custom ECU tune is flashed into your ECU via the Bully Dog GT

  • Flashing the ECU with the GT allows for tuning to be done 100% correctly for smooth power delivery at all altitudes

  • Many stock mapping issues are addressed and the oil pump is turned up

  • Bully Dog GT can be mounted and used as a gauge to display knock, EGT and more

  • Durability pistons and spacer plate for greater motor longevity

  • Low altitude riders 0-6000 ft require the big bore muffler to run properly

  • Kit Includes: Exchange Big Bore Cylinders, Machined Exhaust Valve Assembly, Machined Top Case Half, 2 Pistons with rings, circlips & wristpins, 860 Billet Head Kit, Durability Cylinder Spacer Kit, Ceramic Pipe, Ceramic Y-Pipe, Custom Tuned Bully Dog GT, Stage 2 Clutch Kit

  • Requires your top case half & exhaust valve assembly to be sent in for machining

  • 2015-17 models require a 2018-Up Thermostat and stat housing (additional $100)

  • Requires your cylinders to be sent in as a core exchange (Cores must be in usable condition)

  • 2-5 week turnaround time (depending on availability)

  • Need replacement wrist pin bearings? Find them here

  • Part Number: ADBM09-306-COM


  • Must have Muffler with low elevation


Are you looking for the most possible horsepower and torque from your AXYS 800 H.O.? You should know by now to look no further than BMP as we crank out the most powerful Polaris 800 motors on the planet. Our big bore kit delivers unreal performance and longevity. We spent many hours on the dyno developing this kit and a full year on the snow testing to perfection. This kit cranks out 190 horsepower with huge arm pulling torque (120 ft/lbs)!

Our recipe is simple yet effective: We start off with boring your stock cylinder out for those larger pistons. Next, we draw out a cylinder port map and get to work machining the ports to the specs we know provide the most horsepower possible. The cylinders are then sent out for Nikasil plating and measured to make sure piston to cylinder clearances are within spec. Once the cylinders are 100% completed, we must bore your top case half and grind your exhaust valves to the bore and ports (Must send complete exhaust valve assembly but DO NOT DISASSEMBLE THE ASSEMBLY). The next step is our billet head kit with our specially designed domes for the 860cc power plant which are available in low or high compression. Our custom made Wossner pistons are about as trick as a piston can get! These are coated to help aid break-in and lubricate the skirts. These are also a Durability style piston in which the skirts are longer for less piston rock and increase top end life while also featuring lubrication holes and rings that have further spacing for better cooling properties. This kit also includes our BMP pipe, BMP Y-Pipe & our custom tune loaded via the Bully Dog GT. Clutching is also 100% necessary so we of course include our Stage 2 clutch kit. If you are riding below 6000 ft you will also need to purchase our big bore muffler for proper performance. Our ultimate kit ensures you get everything needed to make a stock sled into a complete monster! Cylinders are on an exchange program while exhaust valves and top case halves are simply machined and sent back to the same customer. Depending on exchange cylinder stock, turnaround time is 2-5 weeks on this kit. Please e-mail or call for current availability.

Bikeman Performance Emissions Regulation Notice

 *Once this performance tuner has been installed on your vehicle, the vehicle is considered “For Competition Use Only”

§1068.235 Exempting nonroad engines/equipment used solely for competition.

(b) If you modify any nonroad engines/equipment after they have been placed into service in the United States so they will be used solely for competition, they are exempt without request.

(c) If you modify any nonroad engines/equipment under paragraph (b) of this section, you must destroy the original emission labels. If you loan, lease, sell, or give any of these engines/equipment to someone else, you must tell the new owner (or operator, if applicable) in writing that they may be used only for competition.

Owner Responsibility:

Individuals engaging in performance enhancement and support must understand and comply with applicable Federal and State laws, including but not limited to compliance with US Environmental Protection Agency (EPA) emissions regulation. To use the competition exemption noted above:

Owners must destroy any existing emissions label installed by the manufacturer. If the emissions label is combined with other content, only the portion of the label related to emissions need be destroyed. This does not pertain to vehicles already exempted and labeled as competition-only vehicles from the factory

Owners of vehicles modified for competition must inform, in writing, any purchaser of the vehicle that it has been exempted from EPA regulations and therefore may be used only for competition.

By installing this performance tuner, you recognize that Bikeman Performance has informed you of certain obligations necessary for competition use of your vehicle.

No single action on your part is as important as proper engine break-in


Do not operate at full throttle or high speeds for extended periods during the first three hours of use.

Watch the video below for proper engine break-in protocol: