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GP Series Honda CR250R Wiseco Top End Kit – 66.40 mm Bore

Your Price: $276.12

SKU: PK1381

Estimated Shipped Date 3-4 Weeks

Wiseco 2 Stroke GP Series Piston Kit, 66.40 mm Bore

Wiseco’s GP Series forged 2-stroke pistons build on the tried-and-true base of the Pro-Lite. Wiseco GP Series 2-stroke pistons incorporate additional performance and durability enhancing features including an Electra-Coated crown, ring groove(s), and pin bores plus ArmorGlide skirt coating, making them perfect for endurance and sustained-RPM 2-stroke applications. From play riders putting in hard hours to consistent competition, GP Series 2-stroke pistons are up to the challenge.

  • Designed for endurance and sustained-RPM 2-stroke riding
  • Engineered, forged, and machined in the USA in Mentor, OH
  • Designed with optimized features for long service life and top-end power
  • Electra-Coated crown, ring groove and pin bore resists potential wear, combustion heat damages, and ring micro-welding
  • ArmorGlife skirt coating reduces friction to optimize performance potential
  • Extra lightening operations for enhanced throttle response
  • High-quality ring(s), wrist pin(s), and circlips included

GTIN: 00193564152138

Product Series

2 Stroke GP Series

Included Components

Piston #860M06640, Ring Set #2614CS, Wrist Pin #S508, CirClip #CW18, Bearing #B1003, Gasket #W6351

Bore Diameter

66.40 MM

Piston Diameter

66.35 MM

Skirt Coating


Piston Oversize


Instructions: Enter a value in the un-shaded boxes below as they pertain to your engine.
Note: For pistons BELOW the block @ TDC – value in box must be a POSITIVE number (.000)
Note: For pistons ABOVE the block @ TDC – value in box must be a NEGATIVE number (-.000)
Note: For a DISH piston – value in box must be a POSITIVE number (0.0)
Note: For a DOME piston – value in box must be a NEGATIVE number (-0.0)
Note: Manipulate the DOME/DISH & PISTON to DECK volumes to get the ratio you want.
Enter the number of cylinders of your engine
Finished bore of your engine
Stroke of your engines crankshaft
Rod Length
Ctr. to Ctr. length of your connecting rods
Gasket Bore
Head Gasket bore diameter
Comp. Gasket
Compressed Head Gasket thickness
Block Deck Height
Center of main bearing bore to top of block
Top Ring Down
Top of 1st ring to top of pistons(FLAT)
Chamber Volume
Cylinder Head chamber volume in CC’s
Dome/Dish Volume
DOME (-) or DISH (+) vol. (theoretical) in CC’s
Piston to Deck
Top of BLOCK to top of piston (FLAT) @ TDC
Click “Calculate” for dimension results.
Total Volume
Cylinder Volume
Total cylinder volume in CC’s =
Clearance Volume
All effective vol. above block deck @ TDC in CC’s =
Gasket Volume
Volume of your head gasket in CC’s =
Top Ring Volume
Total volume above the top ring @ TDC in CC’s =
Deck Volume
Volume of area above the pistons @ TDC in CC’s =
Piston Top Land
Piston top land diameter for volume calculations =
1/2 Stroke
1/2 stroke of your engine’s crankshaft in inches =
Compression Ht.
Ctr. of piston pin to top of piston (FLAT) in inches =
Cubic Inches
Cubic inch displacement of your engine =
For the given dimensions, your compression ratio