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 - 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: -
PROX Piston Kit 01.1342.C
PROX
$185.95When your engine demands precision and reliability, factory-original performance isn't negotiable. The PROX Piston Kit 01.1342.C delivers OEM-equivalent durability through meticulous Japanese manufacturing and high-silicon aluminum construction, ensuring...09030815- SKU:
- 09030815
- Availability:
- Ships Same Business Day
- Weight:
- 0.52 LBS
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.80 MM
- COMPRESSION RATIO IMPERIAL:
- 13.2:1
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- TOP END
- PISTON SIZE METRIC:
- STANDARD SIZE A
$185.95Qty in Cart: 0Quantity:Price:$185.95Subtotal: -
PROX Piston Kit 01.1342.B
PROX
$185.95Worn or damaged pistons compromise combustion efficiency, reduce power output, and risk catastrophic engine failure. The PROX Piston Kit 01.1342.B delivers OEM-equivalent performance with precision manufacturing that restores your engine to factory...09030816- SKU:
- 09030816
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- TOP END
- COMPRESSION RATIO IMPERIAL:
- 13.2:1
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 76.80 MM
$185.95 -
PROX Piston Kit 01.1414.C
PROX
$195.95A worn or damaged piston kit will compromise engine efficiency, increase blow-by, and risk catastrophic engine failure. The PROX Piston Kit 01.1414.C delivers OEM-grade replacement performance with precision-engineered tolerances and high-silicon...09030819- SKU:
- 09030819
- Availability:
- Ships Same Business Day
- Weight:
- 0.88 LBS
- BORE SIZE METRIC:
- 96.00 MM
- PRODUCT NAME:
- PISTON KIT
- COMPRESSION RATIO IMPERIAL:
- 12.0:1
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- ENGINE TYPE:
- 4-STROKE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
$195.95Qty in Cart: 0Quantity:Price:$195.95Subtotal: -
PROX Piston Kit 01.1411.B
PROX
$195.95When your engine's pistons are worn or damaged, you're losing compression, efficiency, and power—and risking catastrophic failure. The PROX Piston Kit 01.1411.B delivers OEM-equivalent performance with precision manufacturing that ensures reliable...09030823- SKU:
- 09030823
- Availability:
- Ships Same Business Day
- Weight:
- 0.79 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- TOP END
- BORE SIZE METRIC:
- 95.97 MM
- RIDING STYLE:
- OFF-ROAD
- COMPRESSION RATIO IMPERIAL:
- 12.0:1
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$195.95Qty in Cart: 0Quantity:Price:$195.95Subtotal: -
PROX Piston Kit 01.2114.C
PROX
$99.95When your engine's pistons wear beyond safe operating limits, you're facing compromised compression, oil blow-by, and potential catastrophic failure. The PROX Piston Kit 01.2114.C delivers OEM-equivalent performance with the precision engineering of...09030828- SKU:
- 09030828
- Availability:
- Ships Same Business Day
- Weight:
- 0.32 LBS
- BORE SIZE METRIC:
- 47.50 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- PRODUCT NAME:
- PISTON KIT
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- EACH
$99.95 -
PROX Piston Kit 01.2429.C
PROX
$195.95Your engine's heart demands precision engineering and materials that can withstand extreme combustion pressures cycle after cycle. The PROX Piston Kit 01.2429.C delivers exactly that—OEM-equivalent performance with the reliability of a...09030829- SKU:
- 09030829
- Availability:
- Ships Same Business Day
- Weight:
- 0.88 LBS
- COMPRESSION RATIO IMPERIAL:
- 12.5:1
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 95.00 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- TYPE:
- TOP END
- UNITS:
- EACH
$195.95 -
PROX Piston Kit 01.4121.C
PROX
$89.95A piston kit is the heart of engine reliability and performance—worn or damaged pistons directly compromise compression, power delivery, and engine longevity. The PROX Piston Kit 01.4121.C delivers OEM-equivalent quality at a fraction of the cost,...09030830- SKU:
- 09030830
- Availability:
- Ships Same Business Day
- Weight:
- 0.33 LBS
- BORE SIZE METRIC:
- 48.50 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- TOP END
$89.95Qty in Cart: 0Quantity:Price:$89.95Subtotal: -
On Sale
PROX Piston Kit 01.1323.A
PROX
MSRP: $143.95Now: $119.00Was: $143.95When your engine's pistons show signs of wear or damage, replacement isn't optional—it's essential for maintaining compression, preventing catastrophic failure, and preserving your engine's performance envelope. The PROX Piston Kit 01.1323.A delivers...PX1322A- SKU:
- PX1322A
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 66.34 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.34 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
MSRP: $143.95Now: $119.00Was: $143.95Qty in Cart: 0Quantity:Price:MSRP: $143.95Now: $119.00Was: $143.95Subtotal:
