Jetworks 850 Super Bore SS Top End Kit

Jetworks 850 Super Bore SS Top End Kit
The Jetworks 850cc Super Bore is the biggest stock stroke engine modification available for the 61x cylinder. This is the step above the more traditional 771cc Big Bores, taking the first bore to 88 mm. If you are looking for more of what a 771 is going to give you then this is the modification your looking for. The port timings on the 61x cylinder is more favorable for freestyle/freeride application. No need to upgrade to a 62t or 64x cylinder that will not match your current exhaust set up. Our porting specs give you a very wide and predictable power-band that pulls extremely low but continues to climb well after the mid range. The power-band is not a “light switch” but rather very linear with instant acceleration whenever you want it. There is no waiting for the power-band to hit. 850cc’s, OEM Cylinder, and stock stroke crankshaft, what more do you want?

*Pro Freerider Wesley Krautkramer Use's this exact engine with Balck Jack 38mm TT's in his Jetworks Build Krash Footrocket

We recommend that you minimally use our OEM 38mm T.T. Modified Carbs, and for a more aggressive hit use a set of Blackjack 44 or 46 Carburetors.

The 850cc Big Bore modification includes:

Removal of OEM Sleeves
Jetworks Custom Sleeves & Installation
Jetworks Custom Wiseco Pistons
Jetworks Super Bore Girdle Head
Jetworks Custom Domes (Pump, AV, or Race Gas)
Cylinder Porting & Honing
Cylinder Boring & Counter Bore
Cylinder Decking
Chamfer Of All Ports
Base Gasket & Wrist Pin Bearings
Replacement pistons available in:

88.0mm @ 828cc
88.5mm @ 837cc
89.0mm @ 846cc
*Requires crankcase Boring

(Optional crankcase porting offers increased acceleration)

*Stroker Packages Available in:

+5mm @ 888cc and 898cc with 88.5 Pistons
Perfect For AM Freestyle Competition.