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447 Big Bore Kit-80mm. (750cc)

$659.95 659.95
In stock
Only 7 left

Big Bore Cylinder and Piston Kit

ALL NEW PARTS!  The ultimate complete bolt on Big Bore 750cc Cylinder and piston kit made for the XS650 Yamaha.

Kit Fits: 1974-84 447 Type Engines


Modified limited production European Race Engine Cylinder Block has enlarged fins for improved cooling. The New Cylinder Block has longer fins matching the Head Fin Length.

Kit Includes:

 One of our XS Performance Big Bore Race Cylinder Block with sleeves installed and finished to fit our 80mm. Forged Big Bore (750cc.) Pistons. Cylinder casting has larger cooling fins that extend out the same distance as the cylinder head fins for enhanced cooling. No modifications to engine cases needed.

Two 80mm, 750cc Big Bore Piston kits complete with Ring Sets, Piston Pins & Clips.

Precisioned machined 447 type Pistons feature:

                    a. Valve pockets cut for large valves.

                    b. Oil channel for enhanced piston pin oiling.
                    c. 20mm. piston pins that are internally tapered to ends for weight reduction.
                    d. 9:1 compression pistons. 

Fitted with our XS Performance Camshaft, Carbs, a free flowing Exhaust and Iridium spark plugs will result in about 65 Rear wheel Horsepower or more and 50 foot pounds of Torque.

Dyno Chart 1 Dyno Chart 2

Is Universal Part: No

OEM Number(s): N/A

Motorcycle Fitment:

  • 1974 Yamaha TX650 TX650A
  • 1975 Yamaha XS650 XS650B
  • 1976 Yamaha XS650 XS650C
  • 1977 Yamaha XS650 XS650D
  • 1978 Yamaha XS650 XS650E
  • 1979 Yamaha XS650 XS650F
  • 1980 Yamaha XS650 XS650G Special II
  • 1981 Yamaha XS650 XS650H Special II
  • 1982 Yamaha XS650 XS650J
  • 1983 Yamaha XS650 XS650K