AXYS 850 to 900 Big Bore Engine Kit

AXYS 850 to 900 Big Bore Engine Kit


Regular price $2,524.95

  • AXYS 900 Big Bore top end kit fits all 2016 AXYS 850 models

  • 195-215 horsepower! (Depending on exhaust configuration)

  • Huge mid-range and torque gain!

  • Hard to keep the skis on the ground!

  • A Torque Link tune, BMP performance manifold, Fatt Azz Pipe and clutching changes are required.

  • For best results, purchase our complete big bore.

  • Turnaround time can vary from 1-15 business days for this kit depending on if core cylinders are in stock. Normal turnaround time is between 3-5 business days.

  • Must send in cylinders and exhaust valves (blades only), unless you select to purchase outright.

  • Recommended Options: ECU tune (Torque Link or Hard Flash), Performance Manifold, Fatt AZZ Pipe & Clutch Kit. If you are running low altitude, you will also want to purchase a BMP big bore muffler - choose between a trail friendly Full Velocity or our super light and loud Powder Lite.

  • If you are just ordering the big bore without the performance kit we can not help you on tuning

  • Use this Work Order Form when sending parts so shipping/receiving knows how to identify them. 

  • Part #: ADBM09-311

  • Cylinder Core Exchange Options (see drop-down menu):

    • Option 1: Purchase Outright - No core cylinder, head or exhaust valves are required to be sent in - Raises kit price by $1450

    • Option 2: Exchange Parts, MUST send your cylinder and exhaust valves within 14 business days. As soon as you do, the charge will be refunded. Exchange parts not received in that amount of time will have no credit applied, and the customer will have to pay for return shipping. 

    • Option 3: Exchange Parts - Your order will be pulled on our shelf waiting for your exchange cylinder, head & exhaust valves to arrive. Once they arrive, we will normally ship the kit within a few business days. No core charge will be applied since we will have your cylinder prior to shipping the big-bore cylinder. 

    Low elevation must use our "Big Bore" muffler


Here at the Bikeman Performance state of the art R&D facility, we were excited to get our hands on the Polaris AXYS 850 powerplant. We were lucky enough to get a pre-production sled to start testing early on. We realized pretty quickly that there is plenty of room for this beast to get even better. The cylinder walls have plenty of beef to bore out to a massive 88mm. The computer simulation laid out a great starting point for our development. With fine refinements and full fuel control using the all-new Torque Link technology, the 900 was born. It takes the regular Polaris 850 full BMP exhaust, 900cc Billet Head and a BMP Big Bore Muffler. 

The Bikeman Performance 900 is a tremendous powerplant making an arm stretching 215 horsepower and 130 lbs/ft of torque! This big bore setup should be used with a Bikeman Performance big bore muffler at low elevation (0-6,000 ft) to get rid of the extra exhaust flow the 900 creates. Using computer simulations, we knew just about where our port timing should end up so we used it as our starting point. Through many dyno pulls, we made slight adjustments to the porting to further maximize output while maintaining durability. Then it was off to test this engine for a solid year in many applications to prove its longevity. The engine is now ready for market to help you pull past, out climb, and make your friends feel slow.


Simply send us you stock cylinder, head and exhaust valves (Blades only please). We will then bore your cylinders, port them, modify your stock head, and machine your exhaust valves. For the best results go with our complete big bore kit which includes everything you need for the big bore motor package.

Kit Includes: Exchange Cylinders, Exchange Exhaust Valves, Billet Head Kit, Pistons, rings, circlips, and wrist pins. Gaskets not included. Replacement OEM o-rings and gaskets recommended.

Recommended Options: ECU tune (Torque Link or Hard Flash), Performance Manifold, Fatt AZZ Pipe & Clutch Kit. If you are running low altitude, you will also want to purchase a BMP big bore muffler - choose between a trail friendly Full Velocity or our super light and loud Powder Lite.

 ***Unless purchasing outright is an additional $1450 -  You must send in cylinders, head, and exhaust valves (Blades Only)*** Package all contents VERY CAREFULLY and insure the package. BMP is not responsible for damages that occur in shipping. Core parts must be in good, usable condition. Parts not in usable condition will not be credited and the customer will be responsible for return shipping.

Click here to download the general big bore instructions