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Cylinder Works Big Bore Cylinder Kit - 21003-K01

  • Part #:
    140670
  • Manufacturer Part #:
    21003-K01

MSRP Price: $579.85

Our Price: $521.87

You Save $57.98 (10%)
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Overview of Cylinder Works Big Bore Cylinder Kit - 21003-K01

+3mm Big Bore Kit Makes it a 478cc

  • Ready-to-install, direct bolt-on cylinders require no re-plating and look virtually identical to the OEM cylinders
  • Cylinder kits include matched Vertex pistons to ensure longevity, performance and reduced engine noise
  • Nickel Silicon Carbide plated for long life
  • Kits come complete with gaskets, cylinder, piston, rings, pin and clips
  • Honed to exact size for easy piston installation
  • Big bore cylinders do not require machine work (unless noted)
  • Made in the U.S.A.

Compression Ratio:12.5:1

Bore: 98mm

REPLACEMENT PARTS:

Replacement Big Bore Cylinder: MFG No. 21003
Replacement Big Bore Piston Kit: MFG No. 21003-P01
Replacement Big Bore Piston Rings: MFG No. 21003-R01
Replacement Big Bore Gasket Kit: MFG No.21003-G01



Included Items:

(1) Cylinder
(1) Piston
(1) Wrist pin
(2) Cir-clips
(1) Top ring
(2) Oil rings
(1) Spacer ring
(1) Cylinder head gasket
(1) Cylinder gasket
(1) Exhaust gasket
(1) Case gasket
Instructions

Specs for Cylinder Works Big Bore Cylinder Kit - 21003-K01

Bore Size 98 mm
Compression Ratio 12.5:1
Type Big Bore Kit
Units Each
Weight 4.05 lbs

Alternate/OEM Part Number(s):

09310174
Specs for Cylinder Works Big Bore Cylinder Kit - 21003-K01
Bore Size 98 mm
Compression Ratio 12.5:1
Type Big Bore Kit
Units Each
Weight 4.05 lbs
Fitment for Cylinder Works Big Bore Cylinder Kit - 21003-K01
See if this part fits your ride

Part 140670 fits the following machines

Yamaha
  • 2009 Yamaha YZ450F
  • 2008 Yamaha YZ450F
  • 2007 Yamaha YZ450F
  • 2006 Yamaha YZ450F
  • 2006 Yamaha YZ450FSP 50th Anniversary Edition
5.0 / 5.0
2 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Stars
2
0
0
0
0
Fit
5.0 / 5
Quality
4.5 / 5
Style
4.5 / 5
Value
4.5 / 5
Fit
5 / 5
Quality
5 / 5
Style
5 / 5
Value
5 / 5
Great up-grade
I put this big bore kit on my bike , and wow everything fit excellent and it was so easy. I got so much more power now when i'm up in the mountains and over on the track. It was well worth the money and it was so quick to change out. I'm satisfied and happy with my choice.
March 2, 2010
Fit
5 / 5
Quality
4 / 5
Style
4 / 5
Value
4 / 5
No Review Title Entered By User
Great power increase in my WR450. The C-clips for the piston wrist pin are a bit difficult. I think the design would need a lock ring...All over good choice. Recommend rejetting your carb and a quick shot excellerator pump cover for best performance.
August 7, 2011
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Instructions and Manuals for Cylinder Works Big Bore Cylinder Kit - 21003-K01