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 01.1222.B
PROX
$105.95If your engine is showing signs of wear—loss of compression, increased blow-by, or worn ring grooves—a quality piston kit is your most direct path to restored performance and reliability. The PROX Piston Kit 01.1222.B delivers OEM-equivalent engineering...09100429- SKU:
- 09100429
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.95 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
$105.95 -
PROX Piston Kit 01.3122.A
PROX
$99.95When your engine is running at the edge of performance, factory pistons become a liability. The PROX Piston Kit 01.3122.A delivers OEM-equivalent reliability with precision manufacturing that keeps your engine balanced and efficient through sustained...09100431- SKU:
- 09100431
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 47.94 MM
- BORE SIZE METRIC:
- 47.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$99.95 -
PROX Piston Kit 01.3122.B
PROX
$99.95A piston kit is the foundation of reliable engine performance—when factory pistons wear or fail, you need a direct OEM replacement that matches original specifications precisely. The PROX Piston Kit 01.3122.B delivers the exact geometry, material...09100432- SKU:
- 09100432
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- PISTON DIAMETER METRIC:
- 47.95 MM
- BORE SIZE METRIC:
- 47.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
$99.95 -
PROX Piston Kit 01.3224.A
PROX
$105.95A worn or damaged piston compromises combustion efficiency, fuel economy, and overall engine reliability. The PROX Piston Kit 01.3224.A delivers OEM-equivalent performance with precision engineering, giving you the confidence to push your engine to its...09100434- SKU:
- 09100434
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$105.95 -
PROX Piston Kit 01.3224.B
PROX
$101.95When your engine demands precision and reliability at high RPM, compromised pistons will cost you performance—and credibility. The PROX Piston Kit 01.3224.B delivers OEM-equivalent performance through Japanese engineering and CNC-machined accuracy,...09100435- SKU:
- 09100435
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- BORE SIZE METRIC:
- 53.96 MM
- PISTON DIAMETER METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$101.95 -
PROX Piston Kit 01.3420.B
PROX
$185.95A piston kit is the heart of your engine's combustion cycle—worn or damaged pistons compromise compression, power delivery, and reliability. The PROX Piston Kit 01.3420.B delivers OEM-equivalent performance with the precision engineering of a Japanese...09100438- SKU:
- 09100438
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$185.95 -
PROX Piston Kit 01.2429.A
PROX
$210.95A piston kit is the heart of reliable engine performance, and worn or damaged pistons compromise compression, power delivery, and fuel efficiency. The PROX Piston Kit 01.2429.A delivers OEM-equivalent quality with precision manufacturing, ensuring your...09100439- SKU:
- 09100439
- Availability:
- Ships Same Business Day
- Weight:
- 0.57 LBS
- BORE SIZE METRIC:
- 94.95 MM
- PISTON DIAMETER METRIC:
- 94.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$210.95 -
PROX Piston Kit 01.2429.B
PROX
$210.95A worn or damaged piston compromises combustion efficiency, reduces power output, and risks catastrophic engine failure. The PROX Piston Kit 01.2429.B delivers OEM-equivalent performance with precision engineering, restoring your engine to factory...09100440- SKU:
- 09100440
- Availability:
- Ships Same Business Day
- Weight:
- 0.82 LBS
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 94.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- BORE SIZE METRIC:
- 94.96 MM
- PRODUCT NAME:
- PISTON KIT
$210.95 -
PROX Piston Kit 01.1111.B
PROX
$93.95When your engine's pistons wear out, performance and reliability suffer—and replacement is non-negotiable. The PROX Piston Kit 01.1111.B delivers OEM-equivalent quality without the dealership markup, engineered to restore your engine's original...09100913- SKU:
- 09100913
- Availability:
- Ships Same Business Day
- Weight:
- 0.31 LBS
- BORE SIZE METRIC:
- 46.95 MM
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 46.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
$93.95 -
PROX Piston Kit 01.1111.C
PROX
$93.95When your engine's pistons show wear or you're rebuilding after high-mileage use, OEM-equivalent replacement is non-negotiable for reliability and performance. The PROX Piston Kit 01.1111.C delivers Japanese manufacturing precision with high-silicon...09100914- SKU:
- 09100914
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 46.96 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 46.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- PISTON SIZE METRIC:
- STANDARD
$93.95 -
PROX Piston Kit - Standard - Yamaha YZ 65 01.2018.A
PROX
$88.95The PROX Piston Kit delivers the reliability and precision your Yamaha YZ 65 demands in high-stress offroad conditions. Whether you're rebuilding after hard use or upgrading your engine package, this OEM-quality piston ensures consistent power delivery...09105694- SKU:
- 09105694
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE SIZE METRIC:
- 43.44 MM
- BORE - OVERSIZE:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$88.95 -
PROX Piston Kit - Standard - Yamaha YZ 65 01.2018.B
PROX
$88.95The PROX Piston Kit maintains optimal compression and reliable performance in your YZ 65, whether you're running stock power or building toward higher output. OEM pistons wear over time, causing compression loss, blow-by, and reduced throttle response—a...09105695- SKU:
- 09105695
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- BORE - OVERSIZE:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- BORE - OVERSIZE METRIC:
- STANDARD
- UNITS:
- KIT
- BORE SIZE METRIC:
- 43.45 MM
- PRODUCT NAME:
- PISTON KIT
$88.95Qty in Cart: 0Quantity:Price:$88.95Subtotal: -
PROX Piston Kit - Standard - Yamaha YZ 65 01.2018.C
PROX
$88.95The PROX Piston Kit keeps your YZ 65 running at peak efficiency through reliable compression and precise bore tolerances. Factory pistons wear down from heat cycles and abrasive riding conditions—upgrading to PROX ensures consistent power delivery and...09105696- SKU:
- 09105696
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- BORE - OVERSIZE:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE SIZE METRIC:
- 43.46 MM
- PRODUCT NAME:
- PISTON KIT
$88.95 -
PROX Piston Kit 01.3413.A
PROX
$210.95Piston failure compromises engine reliability and performance—and substandard replacements accelerate wear across your entire drivetrain. The PROX Piston Kit 01.3413.A delivers OEM-equivalent durability with precision CNC-machining and...09102972- SKU:
- 09102972
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 95.96 MM
- PISTON DIAMETER METRIC:
- 95.96 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$210.95 -
PROX Piston Kit 01.1343.C
PROX
$185.95When your engine demands precision engineering and reliability you can count on, the PROX Piston Kit 01.1343.C delivers OEM-equivalent performance without compromise. Built from high-silicon aluminum alloy and CNC-machined to exacting tolerances, this...09104535- SKU:
- 09104535
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- PISTON DIAMETER METRIC:
- 76.79 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 76.79 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$185.95Qty in Cart: 0Quantity:Price:$185.95Subtotal: -
PROX Piston Kit 01.3341.A
PROX
$188.95Piston failure compromises engine reliability and performance, leaving you stranded or facing catastrophic damage. The PROX Piston Kit 01.3341.A delivers OEM-grade quality with precision engineering, ensuring your engine maintains consistent compression...09104539- SKU:
- 09104539
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- BORE SIZE METRIC:
- 76.96 MM
- PISTON DIAMETER METRIC:
- 76.96 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$188.95Qty in Cart: 0Quantity:Price:$188.95Subtotal: -
PROX Piston Kit 01.3341.C
PROX
$179.95A piston kit is the heart of your engine's combustion cycle—when tolerances wear or ring seal compromises performance, you're losing power and risking catastrophic failure. The PROX Piston Kit 01.3341.C delivers OEM-specification reliability with...09104541- SKU:
- 09104541
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 76.98 MM
- BORE SIZE METRIC:
- 76.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.4342.A
PROX
$188.95Your engine's heart depends on precision-engineered pistons that can handle extreme combustion pressures without compromise. The PROX Piston Kit 01.4342.A delivers OEM-equivalent performance with the manufacturing rigor of Japanese precision engineering,...09104542- SKU:
- 09104542
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- BORE SIZE METRIC:
- 76.96 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 76.96 MM
- RIDING STYLE:
- OFF-ROAD
$188.95 -
PROX Piston Kit 01.4342.B
PROX
$188.95A piston kit is critical to engine longevity and performance—worn or damaged pistons compromise compression, increase blow-by, and accelerate wear on cylinder walls. The PROX Piston Kit 01.4342.B delivers OEM-equivalent quality with CNC precision,...09104543- SKU:
- 09104543
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- BORE SIZE METRIC:
- 76.97 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 76.97 MM
- PISTON SIZE METRIC:
- STANDARD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$188.95 -
PROX Piston Kit 01.6029.D
PROX
$77.95When your engine demands reliability at the limit, OEM-equivalent pistons aren't a luxury—they're essential. The PROX Piston Kit 01.6029.D delivers the precision engineering and material integrity your rebuild requires, engineered in Japan to exact OEM...09104545- SKU:
- 09104545
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 44.99 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 44.99 MM
$77.95Qty in Cart: 0Quantity:Price:$77.95Subtotal:
