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 01.4223.B
PROX
$105.95A piston kit is fundamental to engine longevity and performance—worn or damaged pistons compromise compression, increase blow-by, and accelerate engine wear. The PROX Piston Kit 01.4223.B delivers OEM-equivalent quality without the OEM price tag, using...09100025- SKU:
- 09100025
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON DIAMETER METRIC:
- 53.96 MM
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
$105.95Qty in Cart: 0Quantity:Price:$105.95Subtotal: -
PROX Piston Kit 01.4223.C
PROX
$101.95Worn or damaged pistons directly compromise engine reliability, power delivery, and fuel efficiency—making a quality replacement essential for any serious rebuild or refresh. The PROX Piston Kit 01.4223.C delivers OEM-specification performance with...09100026- SKU:
- 09100026
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- BORE SIZE METRIC:
- 53.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 53.97 MM
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON KIT
$101.95Qty in Cart: 0Quantity:Price:$101.95Subtotal: -
PROX Piston Kit 01.2406.A
PROX
$179.95A piston kit is critical to engine reliability and performance—worn or damaged pistons compromise compression, fuel efficiency, and power delivery. The PROX Piston Kit 01.2406.A delivers OEM-equivalent quality with precision manufacturing, ensuring your...09100027- SKU:
- 09100027
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PISTON DIAMETER METRIC:
- 76.95 MM
- BORE SIZE METRIC:
- 76.95 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$179.95 -
PROX Piston Kit 01.2406.B
PROX
$188.95A worn or damaged piston compromises engine compression, efficiency, and reliability—especially under boost or sustained high RPM. The PROX Piston Kit 01.2406.B delivers OEM-equivalent performance with precision manufacturing that ensures proper ring...09100028- SKU:
- 09100028
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- BORE SIZE METRIC:
- 76.96 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 76.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
$188.95 -
PROX Piston Kit 01.2427.A
PROX
$205.95A worn or damaged piston kit severely limits engine performance and can lead to catastrophic failure if not addressed promptly. The PROX Piston Kit 01.2427.A restores your engine to OEM specifications with precision-engineered components manufactured to...09100031- SKU:
- 09100031
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- BORE SIZE METRIC:
- 94.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 94.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
$205.95 -
PROX Piston Kit - KDX200 '86-'06 01.4285.D
PROX
$132.95A worn or damaged piston directly kills engine performance and reliability. The PROX Piston Kit restores your KDX200 to OEM specifications with Japanese-manufactured precision, ensuring consistent compression, reduced blow-by, and extended engine life...09101453- SKU:
- 09101453
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- PISTON DIAMETER METRIC:
- 65.97 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- ENGINE TYPE:
- 2-STROKE
- SKIRT COATING:
- MOLY COATED
$132.95Qty in Cart: 0Quantity:Price:$132.95Subtotal: -
PROX Piston Kit 01.4409.A
PROX
$189.95If your engine is showing signs of wear—loss of compression, increased blow-by, or declining power output—a quality piston kit is essential to restore performance and reliability. The PROX Piston Kit 01.4409.A delivers OEM-level engineering with...09101465- SKU:
- 09101465
- Availability:
- Ships Same Business Day
- Weight:
- 0.82 LBS
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 95.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 95.97 MM
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.4409.B
PROX
$210.95Pistons are the heart of any engine, and worn or damaged units directly compromise compression, power delivery, and reliability. The PROX Piston Kit 01.4409.B delivers OEM-equivalent performance with precision engineering, making it the ideal choice for...09101466- SKU:
- 09101466
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 95.98 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 95.98 MM
$210.95Qty in Cart: 0Quantity:Price:$210.95Subtotal: -
PROX Piston Kit 01.6604.B
PROX
$229.95When your engine's original pistons show signs of wear, a quality replacement kit is essential to restore compression, reliability, and performance. The PROX Piston Kit 01.6604.B delivers OEM-equivalent construction with precision engineering that...09101524- SKU:
- 09101524
- Availability:
- Ships Same Business Day
- Weight:
- 1.16 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- BORE SIZE METRIC:
- 100.95 MM
- PISTON DIAMETER METRIC:
- 100.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
$229.95Qty in Cart: 0Quantity:Price:$229.95Subtotal: -
PROX Piston Kit 01.2409.A
PROX
$179.95A piston kit is critical to engine reliability and performance—worn or damaged pistons lead to compression loss, increased blow-by, and potential catastrophic engine failure. The PROX Piston Kit 01.2409.A delivers OEM-quality replacement pistons...09101609- SKU:
- 09101609
- Availability:
- Ships Same Business Day
- Weight:
- 0.54 LBS
- BORE SIZE METRIC:
- 76.95 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 76.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.1338.A
PROX
$188.95A worn or damaged piston compromises compression, throttle response, and fuel efficiency—ultimately costing you performance and reliability. The PROX Piston Kit 01.1338.A restores your engine to OEM specifications with Japanese-manufactured precision,...09101126- SKU:
- 09101126
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- BORE SIZE METRIC:
- 77.97 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 77.97 MM
- RIDING STYLE:
- OFF-ROAD
$188.95 -
PROX Piston Kit 01.1338.C
PROX
$188.95When your engine's internals are worn or damaged, OEM-equivalent pistons are non-negotiable for reliable performance and longevity. The PROX Piston Kit 01.1338.C delivers factory-quality construction with Japanese precision manufacturing, ensuring your...09101128- SKU:
- 09101128
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- ENGINE TYPE:
- 4-STROKE
- BORE SIZE METRIC:
- 77.99 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 77.99 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$188.95 -
PROX Piston Kit 01.1339.B
PROX
$185.95When your engine's pistons show wear or you're rebuilding after a high-mileage season, settling for substandard replacements risks catastrophic failure and lost performance. The PROX Piston Kit 01.1339.B delivers OEM-equivalent reliability with precision...09101130- SKU:
- 09101130
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 77.98 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 77.98 MM
- PRODUCT NAME:
- PISTON KIT
$185.95 -
PROX Piston Kit 01.2406.C
PROX
$179.95When your engine demands reliability and precision, OEM-quality pistons are non-negotiable. The PROX Piston Kit 01.2406.C delivers Japanese manufacturing standards with CNC-machined tolerances that restore your engine's original performance...09101133- SKU:
- 09101133
- Availability:
- Ships Same Business Day
- Weight:
- 0.57 LBS
- PISTON DIAMETER METRIC:
- 76.97 MM
- BORE SIZE METRIC:
- 76.97 MM
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
$179.95 -
PROX Piston Kit 01.2427.C
PROX
$185.95When your engine demands precision and reliability, compromised pistons will cost you races and credibility. The PROX Piston Kit 01.2427.C delivers OEM-equivalent performance with the tight tolerances and material integrity that serious racers and...09101139- SKU:
- 09101139
- Availability:
- Ships Same Business Day
- Weight:
- 0.86 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 94.97 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 94.97 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
$185.95 -
PROX Piston Kit 01.3338.A
PROX
$188.95A piston kit is the foundation of reliable engine performance—worn or inadequate pistons lead to compression loss, poor combustion, and premature engine failure. The PROX Piston Kit 01.3338.A delivers OEM-equivalent durability with precision...09101145- SKU:
- 09101145
- Availability:
- Ships Same Business Day
- Weight:
- 0.48 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 76.96 MM
- PRODUCT NAME:
- PISTON KIT
$188.95 -
PROX Piston Kit 01.3338.B
PROX
$179.95When your engine's pistons show wear or you're rebuilding for reliability, OEM-equivalent performance is non-negotiable. The PROX Piston Kit 01.3338.B delivers factory-specification durability without compromise, engineered to maintain precise clearances...09101146- SKU:
- 09101146
- Availability:
- Ships Same Business Day
- Weight:
- 0.48 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 76.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- BORE SIZE METRIC:
- 76.97 MM
- PRODUCT NAME:
- PISTON KIT
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.3410.A
PROX
$189.95A piston kit is one of the most critical components in your engine's combustion chamber—it directly impacts compression ratio, thermal efficiency, and overall power output. The PROX Piston Kit 01.3410.A delivers OEM-grade reliability with precision...09101148- SKU:
- 09101148
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
- BORE SIZE METRIC:
- 95.47 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 95.47 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
$189.95 -
PROX Piston Kit 01.3410.B
PROX
$189.95Your engine's reliability depends on pistons that can handle sustained high RPM loads without sacrifice. The PROX Piston Kit 01.3410.B delivers OEM-equivalent performance with precision manufacturing that ensures consistent ring seal, reduced blow-by,...09101149- SKU:
- 09101149
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- BORE SIZE METRIC:
- 95.48 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 95.48 MM
- PRODUCT NAME:
- PISTON KIT
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.3410.C
PROX
$189.95When your engine demands reliability at high RPM, OEM-quality pistons are non-negotiable. The PROX Piston Kit 013410C delivers factory-specification performance with Japanese manufacturing precision, ensuring consistent compression, reduced blow-by, and...09101150- SKU:
- 09101150
- Availability:
- Ships Same Business Day
- Weight:
- 0.82 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.49 MM
- PISTON DIAMETER METRIC:
- 95.49 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal:
