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 01.6226.A
PROX
$143.95A worn or damaged piston compromises combustion efficiency and can lead to catastrophic engine failure. The PROX Piston Kit 01.6226.A restores OEM-specification performance with precision-engineered components manufactured to exacting tolerances. This...09104546- SKU:
- 09104546
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.94 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 53.94 MM
$143.95 -
PROX Piston Kit 01.6226.B
PROX
$143.95When your engine demands reliability under extreme conditions, factory pistons simply won't cut it. The PROX Piston Kit 01.6226.B delivers OEM-equivalent performance with Japanese precision engineering, ensuring consistent combustion, minimal wear, and...09104547- SKU:
- 09104547
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- PISTON SIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.95 MM
$143.95 -
PROX Piston Kit 01.6226.C
PROX
$124.95When your engine demands reliability at extreme RPMs, OEM-quality pistons are non-negotiable. The PROX Piston Kit 01.6226.C delivers Japanese precision engineering with a complete assembly—pistons, rings, wrist pins, and circlips—eliminating the need for...09104548- SKU:
- 09104548
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- PISTON DIAMETER METRIC:
- 53.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.96 MM
$124.95Qty in Cart: 0Quantity:Price:$124.95Subtotal: -
PROX Piston Kit - MX/EC250 01.7307.B
PROX
$166.95A worn or damaged piston directly compromises engine compression, power delivery, and fuel efficiency—leaving you stranded on the track or trail. The PROX Piston Kit restores your engine to OEM specifications with Japanese-manufactured precision,...09103246- SKU:
- 09103246
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- SKIRT COATING:
- MOLY COATED
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 66.34 MM
- PRODUCT NAME:
- PISTON KIT
$166.95 -
PROX Piston Kit - 71.94 EC300 01.7300.A
PROX
$199.95A properly functioning piston kit is critical to engine reliability and performance—worn or damaged pistons compromise compression, increase blowby, and accelerate engine wear. The PROX Piston Kit 71.94 EC300 is engineered as a direct OEM replacement,...09103248- SKU:
- 09103248
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON DIAMETER METRIC:
- 71.94 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- PISTON MATERIAL:
- ALUMINUM ALLOY
- SKIRT COATING:
- MOLY COATED
$199.95Qty in Cart: 0Quantity:Price:$199.95Subtotal: -
PROX Piston Kit 01.6394.A
PROX
$189.95A piston kit is the heart of your engine's combustion cycle—worn or damaged pistons directly compromise compression, power delivery, and reliability. The PROX Piston Kit 01.6394.A delivers OEM-equivalent performance with Japanese manufacturing precision,...09103257- SKU:
- 09103257
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 71.94 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 71.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.6394.B
PROX
$189.95When your engine demands reliability and precision, factory-spec performance isn't optional—it's essential. The PROX Piston Kit 01.6394.B delivers OEM-equivalent durability with CNC-machined precision, ensuring consistent combustion, optimal ring seal,...09103258- SKU:
- 09103258
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- BORE SIZE METRIC:
- 71.95 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 71.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.4413.A
PROX
$189.95Worn or damaged pistons compromise combustion efficiency, increase blow-by, and accelerate engine wear—ultimately costing you horsepower and reliability. The PROX Piston Kit 01.4413.A restores your engine to OEM performance specifications with...09103266- SKU:
- 09103266
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- PISTON DIAMETER METRIC:
- 95.97 MM
- PISTON SIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.97 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.4413.B
PROX
$210.95A piston kit is mission-critical for any engine rebuild or high-mileage refresh—it's the component that directly translates combustion pressure into power, so quality here impacts reliability and performance across the board. The PROX Piston Kit 01.4413...09103267- SKU:
- 09103267
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- PISTON DIAMETER METRIC:
- 95.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 95.98 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$210.95Qty in Cart: 0Quantity:Price:$210.95Subtotal: -
PROX Piston Kit 01.4413.C
PROX
$189.95A piston kit is fundamental to engine longevity and performance—it directly impacts combustion efficiency, ring seal, and heat dissipation. The PROX Piston Kit 01.4413.C delivers OEM-quality engineering with Japanese manufacturing precision, ensuring...09103268- SKU:
- 09103268
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- PISTON DIAMETER METRIC:
- 95.99 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 95.99 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$189.95 -
PROX Piston Kit 01.6019.B
PROX
$77.95A piston kit is the heart of your engine's combustion cycle—and worn or damaged pistons directly rob you of compression, power, and reliability. The PROX Piston Kit 01.6019.B delivers OEM-equivalent performance with precision engineering and high-silicon...09103270- SKU:
- 09103270
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- PISTON DIAMETER METRIC:
- 39.47 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 39.47 MM
$77.95 -
PROX Piston Kit 01.6019.C
PROX
$77.95A piston kit is critical to engine reliability and performance—worn or damaged pistons compromise compression, increase blow-by, and accelerate engine wear. The PROX Piston Kit 01.6019.C delivers OEM-equivalent quality with precision manufacturing,...09103271- SKU:
- 09103271
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 39.48 MM
- PISTON DIAMETER METRIC:
- 39.48 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
$77.95 -
PROX Piston Kit - 71.94 TM300 01.7302.A
PROX
$221.95When your engine has logged serious hours, piston wear directly compromises compression, fuel efficiency, and power output. The PROX Piston Kit 71.94 TM300 delivers OEM-equivalent performance with precision engineering that restores your engine to...09103287- SKU:
- 09103287
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 71.94 MM
- ENGINE TYPE:
- 2-STROKE
- SKIRT COATING:
- MOLY COATED
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$221.95 -
PROX Piston Kit 01.2414.B
PROX
$179.95When you're rebuilding an engine, piston quality directly impacts reliability, longevity, and performance. The PROX Piston Kit 01.2414.B delivers OEM-equivalent engineering with Japanese manufacturing precision, ensuring your rebuild meets or exceeds...09103421- SKU:
- 09103421
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 76.96 MM
- UNITS:
- EACH
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 76.96 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$179.95 -
PROX Piston Kit 01.2444.A
PROX
$195.95When your engine demands peak performance and reliability, OEM-quality pistons are non-negotiable. The PROX Piston Kit 01.2444.A delivers factory-spec durability with precision engineering, ensuring consistent combustion efficiency and extended engine...09103423- SKU:
- 09103423
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 96.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 96.95 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
$195.95 -
PROX Piston Kit 01.2444.B
PROX
$195.95A worn or damaged piston compromises combustion efficiency, reliability, and overall engine performance. The PROX Piston Kit 01.2444.B delivers OEM-equivalent performance with precision engineering, ensuring your engine runs at peak efficiency whether...09103424- SKU:
- 09103424
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- BORE SIZE METRIC:
- 96.96 MM
- PISTON SIZE METRIC:
- STANDARD
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 96.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$195.95 -
PROX Piston Kit 01.4124.A
PROX
$99.95A worn or damaged piston is a silent killer of engine performance and reliability. The PROX Piston Kit 01.4124.A restores your engine to OEM specifications with precision-engineered components that handle sustained high-RPM operation without compromise...09103429- SKU:
- 09103429
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 48.45 MM
- PISTON DIAMETER METRIC:
- 48.45 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$99.95 -
PROX Piston Kit 01.4124.B
PROX
$99.95When your engine's original pistons show signs of wear, ring blow-by, or loss of compression, a quality replacement kit is essential to restore reliability and performance. The PROX Piston Kit 01.4124.B delivers OEM-equivalent performance with...09103430- SKU:
- 09103430
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PISTON DIAMETER METRIC:
- 48.46 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 48.46 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$99.95 -
PROX Piston Kit 01.4124.C
PROX
$99.95A piston kit is the heart of your engine's combustion cycle—worn or damaged pistons directly compromise compression, power delivery, and reliability. The PROX Piston Kit 01.4124.C delivers OEM-equivalent performance through precision Japanese...09103431- SKU:
- 09103431
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PISTON DIAMETER METRIC:
- 48.47 MM
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 48.47 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD
- UNITS:
- EACH
$99.95 -
PROX Piston Kit - Beta RR300 01.7393.A
PROX
$199.95When your Beta RR300 demands peak performance, compromised pistons will cost you both power and reliability. This PROX piston kit delivers OEM-grade precision and durability with CNC-machined tolerances that ensure consistent combustion and minimal...09103447- SKU:
- 09103447
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- SKIRT COATING:
- MOLY COATED
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 71.94 MM
$199.95
