Dirt Bike Piston and Ring Kits
Dirt Bike Piston & Ring Kits for Yamaha YZ85, WR250 & YZ250 at JJ Motorsports
Rebuild your dirt bike's top end for maximum power and reliability with premium piston and ring kits from JJ Motorsports, forged from high-strength aluminum for superior heat resistance, lightweight performance, and precise fit in motocross, enduro, and trail riding. Our selection includes complete kits with pistons, high-performance rings, wrist pins, circlips, top-end bearings, and gaskets designed for enhanced combustion efficiency, reduced blow-by, and longer engine life under high-RPM abuse. Compatible with popular models like Yamaha YZ85 (2002-2018), WR250, and YZ250, these Wiseco-engineered components feature CNC-machined crowns for optimal cam shape, ArmorGlide skirt coatings for low friction, and 4032 alloy construction for durability in dusty, aggressive conditions. Whether you're refreshing a youth 85cc 2-stroke or upgrading a 250cc big bore, these kits ensure crisp throttle response, better sealing, and race-ready power without the need for custom boring—perfect for DIY rebuilds or pro-level maintenance.
Shop trusted brands like Wiseco for race-proven quality. Explore related categories such as dirt bike engine for cylinders and valves or dirt bike air and fuel for carburetors and jets.
Top Dirt Bike Piston & Ring Kits
- Wiseco YZ85 2002-2018 Piston Kit with Gaskets PK1202 – 47.50mm forged aluminum piston kit for Yamaha YZ85 2-stroke; includes rings, wrist pin, circlips, bearing, and gaskets for enhanced combustion and throttle response.
- Wiseco 68.00mm Piston Kit with Gaskets Yamaha WR/YZ 250 PK1563 – Complete big bore kit for Yamaha WR250/YZ250; features forged piston, rings, wrist pin, circlips, and top-end gaskets for superior power and sealing.
Browse our in-stock inventory below with same-day shipping and expert support. Free shipping on orders over $99! Questions? Contact us for fitment advice!
- Product
- Qty in Cart
- Quantity
- Price
- Subtotal
-
PROX Piston Kit 01.4408.A
PROX
$185.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4330A- SKU:
- PX4330A
- Availability:
- Ships Same Business Day
- Weight:
- 1.18 LBS
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 85.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON DIAMETER METRIC:
- 85.94 MM
- UNITS:
- EACH
$185.95 -
PROX Piston Kit 01.4408.B
PROX
$185.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4330B- SKU:
- PX4330B
- Availability:
- Ships Same Business Day
- Weight:
- 1.18 LBS
- PISTON DIAMETER METRIC:
- 85.95 MM
- BORE SIZE METRIC:
- 85.95 MM
- UNITS:
- EACH
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
$185.95 -
PROX Piston Kit 01.1315.A
PROX
$139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4420A- SKU:
- PX4420A
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 66.34 MM
- PRODUCT NAME:
- PISTON KIT
$139.95 -
PROX Piston Kit 01.1320.A
PROX
$139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4430A- SKU:
- PX4430A
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.34 MM
- PISTON DIAMETER METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$139.95 -
PROX Piston Kit 01.1320.A1
PROX
$139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4430B- SKU:
- PX4430B
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- PISTON DIAMETER METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- BORE SIZE METRIC:
- 66.35 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$139.95 -
PROX Piston Kit 01.3214.B
PROX
$105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5050B- SKU:
- PX5050B
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE B
- BORE SIZE METRIC:
- 53.95 MM
- PISTON DIAMETER METRIC:
- 53.95 MM
- PRODUCT NAME:
- PISTON KIT
$105.95 -
PROX Piston Kit 01.3214.C
PROX
$105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5050C- SKU:
- PX5050C
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 53.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
$105.95 -
PROX Piston Kit 01.3214.D
PROX
$105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5050D- SKU:
- PX5050D
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- BORE SIZE METRIC:
- 53.97 MM
- PISTON DIAMETER METRIC:
- 53.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE D
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
$105.95 -
PROX Piston Kit 01.3220.A
PROX
$101.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5060A- SKU:
- PX5060A
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- PISTON DIAMETER METRIC:
- 53.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$101.95 -
PROX Piston Kit 01.3220.B
PROX
$101.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5060B- SKU:
- PX5060B
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- BORE SIZE METRIC:
- 53.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 53.95 MM
- PRODUCT NAME:
- PISTON KIT
$101.95 -
PROX Piston Kit 01.3220.C
PROX
$105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5060C- SKU:
- PX5060C
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- PISTON DIAMETER METRIC:
- 53.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
$105.95 -
PROX Piston Kit 01.3220.D
PROX
$105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5060D- SKU:
- PX5060D
- Availability:
- Ships Same Business Day
- Weight:
- 0.72 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.97 MM
- PISTON DIAMETER METRIC:
- 53.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE D
- RIDING STYLE:
- OFF-ROAD
$105.95 -
PROX Piston Kit 01.3310.B
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5070B- SKU:
- PX5070B
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 66.94 MM
- PRODUCT NAME:
- PISTON KIT
$129.95 -
PROX Piston Kit 01.3310.C
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5070C- SKU:
- PX5070C
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 66.95 MM
- BORE SIZE METRIC:
- 66.95 MM
- PRODUCT NAME:
- PISTON KIT
$129.95 -
PROX Piston Kit 01.3320.A
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5200A- SKU:
- PX5200A
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 66.34 MM
- PRODUCT NAME:
- PISTON KIT
$129.95Qty in Cart: 0Quantity:Price:$129.95Subtotal: -
PROX Piston Kit 01.3320.B
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5200B- SKU:
- PX5200B
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 66.35 MM
- BORE SIZE METRIC:
- 66.35 MM
- PRODUCT NAME:
- PISTON KIT
$129.95 -
PROX Piston Kit 01.3320.C
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5200C- SKU:
- PX5200C
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON DIAMETER METRIC:
- 66.36 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.36 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
$129.95 -
PROX Piston Kit 01.2314.B
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX7080B- SKU:
- PX7080B
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 67.95 MM
- PISTON SIZE METRIC:
- +0.01 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 67.95 MM
- RIDING STYLE:
- OFF-ROAD
$129.95 -
PROX Piston Kit 01.2314.C
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX7080C- SKU:
- PX7080C
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- PISTON DIAMETER METRIC:
- 67.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 67.96 MM
- PRODUCT NAME:
- PISTON KIT
$129.95 -
PROX Piston Kit 01.2314.D
PROX
$129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX7080D- SKU:
- PX7080D
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE D
- UNITS:
- EACH
- BORE SIZE METRIC:
- 67.97 MM
- PISTON DIAMETER METRIC:
- 67.97 MM
- RIDING STYLE:
- OFF-ROAD
$129.95
