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
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PROX Piston Kit 01.6029.B
PROX
$77.95When your engine demands precision and reliability, OEM-specification pistons are non-negotiable. The PROX Piston Kit 01.6029.B delivers factory-grade performance with the durability required for both street and competition applications, engineered to...09102483- SKU:
- 09102483
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- BORE SIZE METRIC:
- 44.97 MM
- PISTON SIZE METRIC:
- STANDARD
- PISTON DIAMETER METRIC:
- 44.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$77.95 -
PROX Piston Kit 01.6029.C
PROX
$77.95A piston kit is the heart of your engine's combustion cycle—when it fails or wears, you lose compression, power, and reliability. The PROX Piston Kit 01.6029.C delivers OEM-quality replacement pistons engineered to restore your engine to factory...09102484- SKU:
- 09102484
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PISTON DIAMETER METRIC:
- 44.98 MM
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 44.98 MM
- PISTON SIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$77.95Qty in Cart: 0Quantity:Price:$77.95Subtotal: -
PROX Piston Kit 01.4345.A
PROX
$179.95Factory-spec piston performance requires precision manufacturing and material integrity—two areas where OEM replacements often fall short. The PROX Piston Kit 01.4345.A delivers exact OEM dimensions and durability through high-silicon aluminum...09103904- SKU:
- 09103904
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.96 MM
- PISTON DIAMETER METRIC:
- 76.96 MM
- RIDING STYLE:
- OFF-ROAD
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.4345.B
PROX
$179.95When your engine demands reliability under extreme combustion pressures, OEM-equivalent pistons are non-negotiable. The PROX Piston Kit 01.4345.B delivers the precision and durability of factory-spec components without the factory price tag. Whether...09103905- SKU:
- 09103905
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- PISTON DIAMETER METRIC:
- 76.97 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 76.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.4345.C
PROX
$179.95A piston kit is fundamental to engine reliability and performance—it directly impacts compression, combustion efficiency, and overall durability under load. The PROX Piston Kit 01.4345.C delivers OEM-equivalent quality with precision manufacturing,...09103906- SKU:
- 09103906
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- BORE SIZE METRIC:
- 76.98 MM
- PISTON SIZE METRIC:
- STANDARD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 76.98 MM
- RIDING STYLE:
- OFF-ROAD
$179.95 -
PROX Piston Kit 01.4415.C
PROX
$189.95A worn or damaged piston directly compromises engine compression, power delivery, and longevity—requiring immediate replacement to restore factory performance and reliability. The PROX Piston Kit 01.4415.C delivers OEM-equivalent precision engineering at...09103909- SKU:
- 09103909
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON DIAMETER METRIC:
- 95.99 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.99 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.2412.B
PROX
$179.95When your engine demands reliability at high RPM, factory pistons often can't deliver the precision fit and durability required for sustained performance. The PROX Piston Kit 01.2412.B is engineered to OEM specifications using high-silicon-content...09102733- SKU:
- 09102733
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 76.96 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 76.96 MM
- RIDING STYLE:
- OFF-ROAD
$179.95 -
PROX Piston - SuperJet 700 01.2510.100
PROX
$129.95The PROX Piston for SuperJet 700 delivers the reliability and precision your watercraft demands during high-performance operation. A quality piston is critical to maintaining compression, power delivery, and engine longevity—especially in demanding...09102740- SKU:
- 09102740
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- ENGINE TYPE:
- 2-STROKE
- BORE SIZE METRIC:
- 82.00 MM
- PISTON MATERIAL:
- ALUMINUM
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- WATERCRAFT
$129.95 -
PROX Piston Kit - 300EXC TPI '18-'19 01.6388.C
PROX
$189.95When your 300EXC TPI demands peak performance, a worn or damaged piston compromises compression, throttle response, and engine reliability. The PROX Piston Kit delivers OEM-equivalent quality with precision manufacturing that restores your KTM's original...09106268- SKU:
- 09106268
- Availability:
- Ships Same Business Day
- Weight:
- 0.78 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- PISTON KIT
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit - Beta RR300 '18-'19 01.7398.B
PROX
$221.95Your Beta RR300 demands precision engine internals that match factory specifications without compromise. This PROX piston kit is engineered in Japan with high-silicon aluminum and CNC machining to restore or upgrade your top-end performance. Whether...09106269- SKU:
- 09106269
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$221.95 -
PROX Piston Kit - Standard - Yamaha PW50/80 01.2005.000
PROX
$79.95The PROX Piston Kit is engineered to deliver reliable performance and extended service life in demanding offroad conditions. Whether you're rebuilding a worn engine or refreshing your Yamaha PW50/80 for consistent power delivery, this OEM-quality piston...09106097- SKU:
- 09106097
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- BORE SIZE METRIC:
- 40.00 MM
- PRODUCT NAME:
- PISTON KIT
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE - OVERSIZE:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$79.95 -
PROX Piston Kit - Yamaha SJ 700 01.2510.000
PROX
$129.95Off-road riding demands pistons that withstand extreme heat, pressure, and rapid acceleration cycles—factory units often fall short under sustained performance conditions. The PROX Piston Kit delivers precision-engineered internals designed to maintain...09106099- SKU:
- 09106099
- Availability:
- Ships Same Business Day
- Weight:
- 1.05 LBS
- BORE SIZE METRIC:
- 81.00 MM
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
- RIDING STYLE:
- WATERCRAFT
$129.95 -
PROX Piston Kit - Yamaha SJ 700 01.2510.050
PROX
$138.95The PROX Piston Kit is engineered for demanding offroad conditions where stock pistons fall short on durability and heat management. Built to withstand the extreme pressures and temperatures of serious trail riding and competition, this kit delivers the...09106100- SKU:
- 09106100
- Availability:
- Ships Same Business Day
- Weight:
- 1.05 LBS
- BORE SIZE METRIC:
- 81.50 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- KIT
$138.95 -
PROX Piston Kit 01.3001.000
PROX
$79.95High-performance piston kits are essential for offroad engines pushing beyond stock limits—whether you're running increased boost, higher RPMs, or extreme terrain. The PROX Piston Kit 01.3001.000 delivers the durability and precision engineering required...09106101- SKU:
- 09106101
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- RIDING STYLE:
- ATV
- UNITS:
- KIT
- BORE SIZE METRIC:
- 41.00 MM
- PRODUCT NAME:
- PISTON KIT
$79.95 -
PROX Piston Kit - Standard - KTM 50SX 01.6012.A
PROX
$77.95The PROX Piston Kit is engineered to restore your KTM 50SX to factory performance specifications or serve as a critical replacement when wear compromises combustion efficiency and power delivery. A quality piston kit directly impacts throttle response,...09106102- SKU:
- 09106102
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 39.46 MM
- UNITS:
- KIT
- PRODUCT NAME:
- PISTON KIT
$77.95 -
PROX Piston Kit - Standard - KTM 50SX 01.6012.B
PROX
$77.95A quality piston kit is fundamental to maintaining peak engine performance and longevity in high-demand offroad riding. The PROX Piston Kit delivers OEM-grade reliability with precision-engineered tolerances, ensuring consistent compression and reduced...09106103- SKU:
- 09106103
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- BORE SIZE METRIC:
- 39.47 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$77.95 -
PROX Piston Kit - Standard - KTM 65SX 01.6022.A
PROX
$77.95The PROX Piston Kit is engineered to restore your KTM 65SX to factory performance specifications or serve as a reliable replacement for high-mileage engines. Whether you're a weekend rider or a young racer pushing hard on the track, a quality piston kit...09106104- SKU:
- 09106104
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE - OVERSIZE:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE METRIC:
- 44.96 MM
$77.95 -
PROX Piston Kit - Standard - KTM 65SX 01.6022.B
PROX
$77.95The PROX Piston Kit restores your KTM 65SX to OEM specifications with precision-engineered components built to handle the demands of competitive off-road riding. Whether you're rebuilding after a season of hard racing or performing preventative...09106105- SKU:
- 09106105
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 44.97 MM
$77.95 -
PROX Piston Kit - Standard - 125SX 01.6220.A
PROX
$124.95Off-road performance demands pistons engineered for extreme conditions—high RPMs, aggressive throttle response, and sustained heat. The PROX Piston Kit delivers the reliability and precision fit your 125SX needs to maintain peak power delivery across...09106106- SKU:
- 09106106
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- BORE SIZE METRIC:
- 53.94 MM
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$124.95 -
PROX Piston Kit - Standard - KTM 200EXC 01.6249.A
PROX
$139.95The PROX Piston Kit keeps your KTM 200EXC running at peak efficiency through the demands of aggressive off-road riding. When stock pistons wear or fail, you lose compression, power delivery, and fuel economy—this kit restores all three with precision...09106108- SKU:
- 09106108
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
- BORE - OVERSIZE:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE SIZE METRIC:
- 63.94 MM
- PRODUCT NAME:
- PISTON KIT
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal:
