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Yamaha YFM 350 Piston Kits Warrior Pistons Big Bear 350 Piston Kits Standard Bore and Big Bore

Yamaha yfm350 warrior atv wiseco pistons High performance and racing Yamaha piston kits are available here. Buy the best Wiseco Pistons for all model years of the YFM350 Warrior / 350 Big Bear four stroke ATV's. Standard bore size and big bore YFM 350 Big Bear / Warrior 350 big bore Wiseco Pistons Yamaha ATV kits are listed below.

Every Wiseco piston is designed with the proper installed clearance to produce the most power, least wear, and best piston ring seal at operating temperature, for each application. Wiseco forged pistons include coated skirts and provide greater strength, durability and reduced weight compared to stock type pistons. These pistons come with performance piston rings and lightweight piston pins and offer the highest quality and are engineered for maximum performance and durability.


Wiseco YFM 350 Warrior Pistons, Piston Kits, Top End Gasket Kits YFM350 XT & WT Big Bear Piston Kits

Wiseco YFM 350 Pistons Warrior Big Bore Kits

These Wiseco Yamaha pistons, gaskets and kits fit the following models:

  • 1987 - 2004 Yamaha Warrior YFM350 XT
  • 1989 - 1999 Yamaha Big Bear YFM 350 WT
  • 2005 - 2010 Yamaha Raptor 350
  • 1999 Yamaha BW350T
  • 1999 Yamaha Moto 4
List of what is included with the different Wiseco part numbers listed below.


  • Piston with coated skirts
  • Piston Pin
  • Piston Rings
  • Pin Locks

Top end " PK " kit:

  • Piston with coated skirts
  • Piston Pin
  • Piston Rings
  • Pin Locks
  • Top End Gasket Kit

Gasket kit:


  • Complete premium top end gasket set.
  • Includes cylinder base gasket, head gasket, o-rings, seals, etc.
  • Exact contents vary based on engine

Common YFM350 engine specifications

  • Stock Bore is 83mm
  • Stock Stroke is 64.5mm


Bore Size ccs Comp Installation
Piston Top End Kit

Gasket Kit

(fits all models except 1999 BW350T)

83mm std. 349cc 10.25-1 deglaze cylinder

Wiseco 4419M08300


Wiseco PK1018


Wiseco W5746


83.5mm +.5mm big bore 353cc 10.25-1 resize cylinder

Wiseco 4419M08350


Wiseco PK1019


Wiseco W5746


84mm +1mm big bore 357cc 10.25-1 resize cylinder

Wiseco 4419M08400


Wiseco PK1020


Wiseco W5746




CP Pistons, for those that demand the ultimate in engine performance!

NOTE: The below pistons have been discontinued by CP. We are keeping this information available as a tech resource to anyone who may need the original specifications for these pistons.

High performance and racing Yamaha piston kits were available from CP Pistons for all model years of the YFM350 Warrior / 350 Big Bear models. These forged pistons will fit with oversize valves and high lift camshafts because they had oversize valve reliefs. They incorporated a "X" style forging for greater strength, durability and reduced weight.

Standard Features that were included with each Yamaha YFM 350 Warrior Big Bear 350 CP Piston Kit:
Double forced pin oilers Fully CNC Machined
Accumulator groove Pick lock removal grooves
Anti detonation grooves X-style forging
Light weight pins Balanced to + or - 1 gram

Each of the below kits included: Piston, Piston Pin, Piston Rings, Pin Locks

1987 - 2004 Yamaha YFM 350 Warrior ATV CP Pistons brand Piston Kit
2005 - 2006 Raptor 350 ATV CP Pistons brand Piston Kit
Stock Bore: 83mm (3.268")
Stock Stroke: 64.5mm (2.539")

Part # Bore Size Cubic
Compression Top End Gasket Kit # Installation
cp m1012 83mm std. 349cc 10.5-1 cp c7096 deglaze cylinder
cp m1013 83.5mm +0.5mm 353cc 10.5-1 cp c7096 resize cylinder
cp m1014 84mm +1mm 357cc 10.5-1 cp c7096 resize cylinder



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