BMP Polaris 660 Big Bore Kit


Regular price $2,499.00

  • The kit you need to keep up with and normally beat on 800cc sleds!

  • This 660 big bore is wicked fast, responsive, and extremely reliable.

  • 145-148 quick revving horsepower

  • ***Must send in cylinders and exhaust valves***

  • If doing the pipe mod, you must also send your stock pipe.

  • Package components VERY carefully (we are not responsible for any damages during shipping)

  • Turnaround time can vary from 1-3 weeks for this kit depending on if core cylinders are in stock. Kits will normally ship very soon after your core cylinders and exhaust valves are received by BMP. We do grind your same exhaust valves which can have a 2-3 day delay on the order shipping. In a pinch and need a kit out ASAP? Call us and we can charge you for the core and ship your parts right away (depending on stock). 

  • Use this form when sending in engine work: BMP WORK ORDER FORM


Our most popular Polaris big bore kit because they run so strong and reliable! These have been working exceptionally well on the new Pro-R chassis 600 models. Many customers have been whipping up on 800cc sleds!!! For a 660 they really run strong, making 145-148 HP from 8200-8400 RPM. We bore out the cylinders, port them, re-nikasil, and modify the exhaust valves. The kit uses OEM Polaris 81mm pistons and we top it off with our billet head kit. Our billet head has twice the cooling capacity of stock, typically reducing the running engine temp 10-15 degrees.

Kit includes : Boring, porting, & replating your stock cylinders. 2 pistons, rings, circlips, billet head kit, & grinding of stock exhaust valves. Due to many model changes, gaskets are not included. This kit uses all OEM size gaskets.

Recommended Options: Stock Pipe Mod, Stage 2 Clutch Kit, and V-Force Reed Cages. Stage 2 clutch kits vary per year and model, so please find the appropriate clutch kit under your models category. If you need help please call or e-mail. 

If you want that sleeper look you can also go with our stock head mod for $250 less. Please call or e-mail for this option.

EFI models require a Power Commander 5 (Comes with 660 map).

Click here to download the general big bore instructions

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.