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 01.4337.A
PROX
$179.95A piston kit is the core of your engine's combustion cycle—when it fails or wears, power delivery suffers and reliability tanks. The PROX Piston Kit 01.4337.A delivers factory-matched performance with the precision engineering that professional racers...09101153- SKU:
- 09101153
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- BORE SIZE METRIC:
- 76.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 76.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$179.95 -
PROX Piston Kit 01.4337.B
PROX
$188.95When your engine demands precision and reliability, compromised pistons aren't an option. The PROX Piston Kit 01.4337.B delivers OEM-equivalent performance with the durability required for high-demand racing and rebuilt engine applications. Built from...09101154- SKU:
- 09101154
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.97 MM
- PISTON DIAMETER METRIC:
- 76.97 MM
$188.95 -
PROX Piston Kit 01.4337.C
PROX
$179.95When your engine demands reliability under extreme conditions, OEM-quality pistons aren't optional—they're essential. The PROX Piston Kit 01.4337.C delivers factory-spec performance with precision engineering, ensuring consistent compression, reduced...09101155- SKU:
- 09101155
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.98 MM
- PISTON DIAMETER METRIC:
- 76.98 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE C
$179.95 -
PROX Piston Kit 01.4406.A
PROX
$210.95Your engine's pistons are the hardworking heart of combustion—they convert fuel into power thousands of times per minute. When OEM pistons wear, fatigue, or fail, performance drops and reliability suffers. The PROX Piston Kit 01.4406.A restores your...09101156- SKU:
- 09101156
- Availability:
- Ships Same Business Day
- Weight:
- 0.92 LBS
- BORE SIZE METRIC:
- 95.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 95.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$210.95Qty in Cart: 0Quantity:Price:$210.95Subtotal: -
PROX Piston Kit 01.4406.B
PROX
$189.95A worn or damaged piston kit compromises combustion efficiency, power delivery, and engine longevity. The PROX Piston Kit 01.4406.B restores OEM-level performance with precision-engineered components manufactured to exacting tolerances, ensuring reliable...09101157- SKU:
- 09101157
- Availability:
- Ships Same Business Day
- Weight:
- 0.91 LBS
- BORE SIZE METRIC:
- 95.98 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON DIAMETER METRIC:
- 95.98 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.4406.C
PROX
$189.95When your engine is pushing limits, your pistons need to match that intensity. The PROX Piston Kit 01.4406.C delivers OEM-equivalent reliability with Japanese manufacturing precision, ensuring consistent performance across extended high-RPM sessions...09101158- SKU:
- 09101158
- Availability:
- Ships Same Business Day
- Weight:
- 0.92 LBS
- PISTON DIAMETER METRIC:
- 95.99 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.99 MM
- PRODUCT NAME:
- PISTON KIT
$189.95 -
PROX Piston Kit 01.6105.A
PROX
$105.95Your engine's heart deserves precision engineering built to last. The PROX Piston Kit 01.6105.A delivers OEM-grade reliability with the exacting tolerances demanded by both stock rebuilds and high-performance applications. This complete kit eliminates...09101159- SKU:
- 09101159
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 46.95 MM
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 46.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
$105.95Qty in Cart: 0Quantity:Price:$105.95Subtotal: -
PROX Piston Kit 01.6105.B
PROX
$105.95When your engine's pistons wear beyond OEM tolerances, performance and reliability suffer. The PROX Piston Kit 01.6105.B delivers factory-spec replacement pistons engineered to restore combustion efficiency and ring sealing—critical for sustained power...09101160- SKU:
- 09101160
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- PISTON DIAMETER METRIC:
- 46.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 46.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
$105.95 -
PROX Piston Kit 01.6105.C
PROX
$105.95Piston failure cuts a race or rebuild short. The PROX Piston Kit 01.6105.C delivers OEM-equivalent reliability with precision engineering, ensuring your engine maintains peak combustion efficiency and durability under sustained load. This complete kit...09101161- SKU:
- 09101161
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- BORE SIZE METRIC:
- 46.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 46.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- PRODUCT NAME:
- PISTON KIT
$105.95 -
PROX Piston Kit 01.6105.D
PROX
$105.95Your engine's pistons are the hardest-working components under the hood, cycling thousands of times per minute while managing extreme heat and pressure. When OEM pistons wear out or fail, you need a direct replacement that matches factory specifications...09101162- SKU:
- 09101162
- Availability:
- Ships Same Business Day
- Weight:
- 0.28 LBS
- PISTON DIAMETER METRIC:
- 46.98 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 46.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE D
$105.95 -
PROX Piston Kit 01.6343.D
PROX
$166.95When your engine's pistons show wear, you're looking at compromised compression, increased blow-by, and accelerated internal degradation. The PROX Piston Kit 01.6343.D delivers OEM-equivalent performance with Japanese precision engineering, restoring...09101166- SKU:
- 09101166
- Availability:
- Ships Same Business Day
- Weight:
- 0.67 LBS
- PISTON DIAMETER METRIC:
- 66.37 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.37 MM
- PISTON SIZE METRIC:
- STANDARD SIZE D
- PRODUCT NAME:
- PISTON KIT
$166.95 -
PROX Piston Kit 01.6338.B
PROX
$209.99Whether you're rebuilding after high-mileage wear or preparing for sustained performance driving, a quality piston kit is essential to engine reliability and power delivery. The PROX Piston Kit 01.6338.B delivers OEM-equivalent performance with the...09101168- SKU:
- 09101168
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- PISTON DIAMETER METRIC:
- 75.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 75.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
$209.99Qty in Cart: 0Quantity:Price:$209.99Subtotal: -
PROX Piston Kit 01.6338.C
PROX
$209.99When your pistons show wear or you're rebuilding after high-mileage racing, you need a replacement that matches or exceeds OEM performance specifications. The PROX Piston Kit 01.6338.C delivers that reliability with precision Japanese engineering and...09101169- SKU:
- 09101169
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- BORE SIZE METRIC:
- 75.98 MM
- PISTON DIAMETER METRIC:
- 75.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$209.99Qty in Cart: 0Quantity:Price:$209.99Subtotal: -
PROX Piston Kit 01.6427.A
PROX
$195.95Your engine's pistons are the workhorses converting combustion into power—and when they wear, performance suffers. The PROX Piston Kit 01.6427.A delivers OEM-equivalent reliability with precision Japanese manufacturing, ensuring consistent compression,...09101172- SKU:
- 09101172
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 94.94 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 96.94 MM
- PRODUCT NAME:
- PISTON KIT
$195.95 -
PROX Piston Kit 01.6427.C
PROX
$195.95A piston kit is the heart of engine reliability and performance—worn or damaged pistons rob you of compression, efficiency, and power. The PROX Piston Kit 01.6427.C delivers OEM-equivalent quality with Japanese precision engineering, giving you the...09101174- SKU:
- 09101174
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- BORE SIZE METRIC:
- 96.96 MM
- PISTON DIAMETER METRIC:
- 94.96 MM
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON KIT
$195.95 -
PROX Piston Kit 01.6521.A
PROX
$214.95When your engine demands reliability under extreme conditions, OEM-spec pistons are non-negotiable. The PROX Piston Kit 01.6521.A delivers precision-engineered replacement pistons manufactured to exacting tolerances, ensuring consistent compression,...09101182- SKU:
- 09101182
- Availability:
- Ships Same Business Day
- Weight:
- 0.91 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 94.94 MM
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 94.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$214.95Qty in Cart: 0Quantity:Price:$214.95Subtotal: -
PROX Piston Kit 01.6521.B
PROX
$221.95When your engine is running on stock pistons, you're leaving performance on the table and risking catastrophic failure under sustained boost or high RPM loads. The PROX Piston Kit 01.6521.B delivers OEM-equivalent reliability with precision manufacturing...09101183- SKU:
- 09101183
- Availability:
- Ships Same Business Day
- Weight:
- 0.91 LBS
- PISTON DIAMETER METRIC:
- 94.95 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 94.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- ATV
- UNITS:
- EACH
$221.95 -
PROX Piston Kit 01.6521.C
PROX
$221.95Worn or damaged pistons compromise engine efficiency, power delivery, and reliability—especially in high-demand racing and performance applications. The PROX Piston Kit 01.6521.C delivers OEM-equivalent quality with precision engineering, ensuring your...09101184- SKU:
- 09101184
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- BORE SIZE METRIC:
- 94.96 MM
- PISTON DIAMETER METRIC:
- 94.96 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
$221.95Qty in Cart: 0Quantity:Price:$221.95Subtotal: -
PROX Piston Kit 01.1325.A
PROX
$139.95Factory-original performance demands factory-original components. The PROX Piston Kit 01.1325.A delivers OEM-specification reliability without compromise, engineered with precision-cast, high-silicon aluminum that withstands sustained load cycles and...09101187- SKU:
- 09101187
- Availability:
- Ships Same Business Day
- Weight:
- 0.71 LBS
- PISTON DIAMETER METRIC:
- 66.34 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.34 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Kit 01.1325.A1
PROX
$139.95Worn or damaged pistons compromise engine efficiency, boost consumption, and reliability—especially under high-performance conditions. The PROX Piston Kit 01.1325.A1 restores OEM-specification performance with precision-engineered components manufactured...09101188- SKU:
- 09101188
- Availability:
- Ships Same Business Day
- Weight:
- 0.71 LBS
- BORE SIZE METRIC:
- 66.35 MM
- PISTON DIAMETER METRIC:
- 66.35 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal:
