UpShift403 Polaris 1070 Big Bore

UpShift403 loves the Polaris Patriot 850 and 9R platforms. They wanted to offer a kit that utilized the stock crankshaft and a little easier on the wallet without sacrificing that raw, aggressive feel.   Enter the 1070 kit – inspired by legendary Big Bores of the 2000’s .  This package brings back that unmistakable torque curve: a crisp hit off the bottom, bursting through the mid-range and continuing to pull hard all the way to the top. Whether you’re yanking frozen stumps out of the ground or drag racing uphill, the 1070 delivers.

This engine feels like a supercharged 9R, with a gain of 40-45hp from start to finish over a stock 850.  It shares some of the short stroke character of the 9R but keeps it naturally aspirated.

What’s Included in the Kit:

• Cast Big bore cylinder 96mm bore
• Billet head c/w domes & new bolts & billet water fittings
• 2X Forged Piston kits
• Top End Gasket Kit
• Stainless coated base gasket
• New Power Valves to match cylinder – single power valve design
• Bigger Injectors with harness
• Crankcase machining extra – can provide file for local machinist
• Requires ECU Reflash
• Package Price: $5,500.00 CAD

Crankcase Machining Options:
This kit requires crankcase machining to slightly open things up to fit the larger cylinder

• Transfer port case-matching
• Locating ring machining for triple bearing (can Loctite if not machining) if using a billet crank
• Add gas/oil mix passages to PTO and MAG bearings — factory blanks these ports and relies solely on direct oiling

Optional Add-Ons:

• Indy Specialties billet stock replacement crank
• Oil injection delete kit for lightweight builds
• 52mm or 60mm Big Bore Throttle Bodies with injector relocation and custom reed valve adapters
• Fuel Inserts:
• Pump Gas Insert
• 100 Octane Insert
• Race Inserts (110–120 Octane)
• SLP Twin Pipes
• Big Bore Hand-Made Pipes
• Big Bore Single Pipe Kit (Fall 2025)

Why Choose UpShift403’s Kit?

• Proven crankshaft durability with Indy Specialty billet design
• Engineered for peak performance in deep snow
• Pulls harder and longer than any modified 9R on any gas
• Thoughtfully designed for aggressive backcountry riders, flat land speed demons and racers of all kinds