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 01.1111.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,...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
$93.95Qty in Cart: 0Quantity:Price:$93.95Subtotal: -
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...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...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...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
$88.95 -
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...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...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...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,...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
$188.95 -
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...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...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...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...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
$77.95 -
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...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...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,...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...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...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...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...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...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:
