Dirt Bike Engine
Dirt Bike Engine Parts at JJ Motorsports
Discover a full range of dirt bike engine components for rebuilding or upgrading your performance from JJ Motorsports. From crankshafts to cylinder heads and piston kits, these precision-engineered components ensure reliable performance. For additional upgrades, check out our full selection of off-road dirt bike parts to keep your engine running at peak efficiency on the track or trails.
Shop trusted brands like Wiseco for forged piston kits and K&N for high-flow oil filters. Explore related categories such as Dirt Bike Air and Fuel for intake upgrades or Dirt Bike Exhaust for complete systems.
Browse our in-stock inventory below with same-day shipping and expert support. Questions? Contact us for fitment advice!
- Product
- Qty in Cart
- Quantity
- Price
- Subtotal
-
On Sale
PROX Piston Kit 01.1315.A
PROX
MSRP: $139.95Now: $119.00Was: $139.95A piston kit is your foundation for reliable engine performance and longevity. The PROX Piston Kit 01.1315.A delivers OEM-equivalent quality with precision engineering that ensures proper ring...PX4420A- SKU:
- PX4420A
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 66.34 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $139.95Now: $119.00Was: $139.95 -
On Sale
PROX Ring Set 02.1315
PROX
MSRP: $49.95Now: $42.00Was: $49.95Worn piston rings directly compromise combustion efficiency, oil consumption, and overall engine reliability—making a quality replacement essential for consistent performance. The PROX Ring Set 02...PX4420R- SKU:
- PX4420R
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- PISTON RING
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
MSRP: $49.95Now: $42.00Was: $49.95 -
On Sale
PROX Piston Kit 01.1320.A
PROX
MSRP: $143.95Now: $119.00Was: $143.95Your engine's performance and longevity depend on pistons that can withstand extreme temperatures, pressures, and RPMs without compromise. The PROX Piston Kit 01.1320.A is engineered as a direct OEM...PX4430A- SKU:
- PX4430A
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.34 MM
- PISTON DIAMETER METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $143.95Now: $119.00Was: $143.95 -
On Sale
PROX Piston Kit 01.1320.A1
PROX
MSRP: $143.95Now: $119.00Was: $143.95When your engine demands reliable power delivery and long-term durability, stock pistons often fall short of performance expectations. The PROX Piston Kit 01.1320.A1 delivers OEM-equivalent quality...PX4430B- SKU:
- PX4430B
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- PISTON DIAMETER METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- BORE SIZE METRIC:
- 66.35 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
MSRP: $143.95Now: $119.00Was: $143.95 -
On Sale
PROX Piston Kit 01.3214.B
PROX
MSRP: $121.95Now: $90.00Was: $121.95When your engine demands reliability under extreme conditions, OEM-equivalent performance becomes non-negotiable. The PROX Piston Kit 01.3214.B delivers Japanese manufacturing precision with...PX5050B- SKU:
- PX5050B
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE B
- BORE SIZE METRIC:
- 53.95 MM
- PISTON DIAMETER METRIC:
- 53.95 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $121.95Now: $90.00Was: $121.95 -
On Sale
PROX Piston Kit 01.3214.C
PROX
MSRP: $121.95Now: $90.00Was: $121.95A piston kit is fundamental to engine reliability and performance—worn or damaged pistons compromise compression, increase blowby, and risk catastrophic engine failure. The PROX Piston Kit 01.3214.C...PX5050C- SKU:
- PX5050C
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 53.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $121.95Now: $90.00Was: $121.95 -
On Sale
PROX Piston Kit 01.3214.D
PROX
MSRP: $105.95Now: $90.00Was: $105.95A failed or worn piston compromises combustion efficiency, power delivery, and engine reliability. The PROX Piston Kit 013214D delivers OEM-equivalent performance with precision manufacturing that...PX5050D- SKU:
- PX5050D
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- BORE SIZE METRIC:
- 53.97 MM
- PISTON DIAMETER METRIC:
- 53.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE D
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
MSRP: $105.95Now: $90.00Was: $105.95Qty in Cart: 0Quantity:Price:MSRP: $105.95Now: $90.00Was: $105.95Subtotal: -
On Sale
PROX Ring Set 02.3212
PROX
MSRP: $24.95Now: $21.00Was: $24.95Piston rings are critical to engine sealing and compression—worn or damaged rings lead to blow-by, oil consumption, and power loss. The PROX Ring Set 02.3212 delivers OEM-equivalent performance with...PX5050R- SKU:
- PX5050R
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON RING
- UNITS:
- SET
MSRP: $24.95Now: $21.00Was: $24.95Qty in Cart: 0Quantity:Price:MSRP: $24.95Now: $21.00Was: $24.95Subtotal: -
On Sale
PROX Piston Kit 01.3220.A
PROX
MSRP: $121.95Now: $87.00Was: $121.95Your engine's pistons are the hardworking heart of combustion—and when they wear, performance suffers. The PROX Piston Kit 01.3220.A restores your engine to OEM specifications with...PX5060A- SKU:
- PX5060A
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- PISTON DIAMETER METRIC:
- 53.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
MSRP: $121.95Now: $87.00Was: $121.95 -
On Sale
PROX Piston Kit 01.3220.B
PROX
MSRP: $101.95Now: $87.00Was: $101.95A worn or damaged piston directly compromises engine compression, power output, and fuel efficiency—making a quality replacement essential for reliable performance. The PROX Piston Kit 01.3220.B...PX5060B- SKU:
- PX5060B
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- BORE SIZE METRIC:
- 53.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 53.95 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $101.95Now: $87.00Was: $101.95Qty in Cart: 0Quantity:Price:MSRP: $101.95Now: $87.00Was: $101.95Subtotal: -
On Sale
PROX Piston Kit 01.3220.C
PROX
MSRP: $105.95Now: $90.00Was: $105.95Your engine's ability to handle sustained RPMs and maintain combustion efficiency depends entirely on piston quality—worn or substandard pistons lead to blow-by, compression loss, and catastrophic...PX5060C- SKU:
- PX5060C
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- PISTON DIAMETER METRIC:
- 53.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $105.95Now: $90.00Was: $105.95Qty in Cart: 0Quantity:Price:MSRP: $105.95Now: $90.00Was: $105.95Subtotal: -
On Sale
PROX Piston Kit 01.3220.D
PROX
MSRP: $105.95Now: $90.00Was: $105.95Worn or damaged pistons compromise combustion efficiency, reduce power output, and risk catastrophic engine failure. The PROX Piston Kit 01.3220.D delivers OEM-equivalent performance with precision...PX5060D- SKU:
- PX5060D
- Availability:
- Ships Same Business Day
- Weight:
- 0.72 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.97 MM
- PISTON DIAMETER METRIC:
- 53.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE D
- RIDING STYLE:
- OFF-ROAD
MSRP: $105.95Now: $90.00Was: $105.95Qty in Cart: 0Quantity:Price:MSRP: $105.95Now: $90.00Was: $105.95Subtotal: -
On Sale
PROX Piston Kit 01.3310.B
PROX
MSRP: $129.95Now: $110.00Was: $129.95Worn or damaged pistons compromise engine efficiency, power delivery, and longevity. The PROX Piston Kit 01.3310.B restores your engine to OEM performance specifications with precision-manufactured...PX5070B- SKU:
- PX5070B
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 66.94 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $129.95Now: $110.00Was: $129.95Qty in Cart: 0Quantity:Price:MSRP: $129.95Now: $110.00Was: $129.95Subtotal: -
On Sale
PROX Piston Kit 01.3310.C
PROX
MSRP: $129.95Now: $110.00Was: $129.95A worn or damaged piston directly compromises engine efficiency, reliability, and power output. The PROX Piston Kit 01.3310.C delivers OEM-equivalent performance with precision engineering, ensuring...PX5070C- SKU:
- PX5070C
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 66.95 MM
- BORE SIZE METRIC:
- 66.95 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $129.95Now: $110.00Was: $129.95Qty in Cart: 0Quantity:Price:MSRP: $129.95Now: $110.00Was: $129.95Subtotal: -
On Sale
PROX Piston Kit 01.3320.A
PROX
MSRP: $143.95Now: $110.00Was: $143.95When your engine's original pistons show signs of wear—whether it's blowby, loss of compression, or declining performance—a quality replacement kit restores cylinder sealing and combustion efficiency...PX5200A- SKU:
- PX5200A
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.34 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 66.34 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $143.95Now: $110.00Was: $143.95 -
On Sale
PROX Piston Kit 01.3320.B
PROX
MSRP: $143.95Now: $110.00Was: $143.95A piston kit is the heart of your engine's combustion cycle, and worn or damaged pistons rob you of compression, power, and reliability. The PROX Piston Kit 01.3320.B delivers OEM-equivalent...PX5200B- SKU:
- PX5200B
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 66.35 MM
- BORE SIZE METRIC:
- 66.35 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $143.95Now: $110.00Was: $143.95 -
On Sale
PROX Piston Kit 01.3320.C
PROX
MSRP: $129.95Now: $110.00Was: $129.95When engine wear compromises compression and power delivery, a quality piston kit is the foundation of a proper rebuild. The PROX Piston Kit 01.3320.C delivers OEM-equivalent performance with...PX5200C- SKU:
- PX5200C
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON DIAMETER METRIC:
- 66.36 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.36 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
MSRP: $129.95Now: $110.00Was: $129.95Qty in Cart: 0Quantity:Price:MSRP: $129.95Now: $110.00Was: $129.95Subtotal: -
On Sale
PROX Piston Kit 01.2314.B
PROX
MSRP: $132.95Now: $110.00Was: $132.95A piston failure means catastrophic engine damage—and the PROX Piston Kit 01.2314.B is engineered to prevent exactly that. Built to OEM specifications using high-silicon aluminum and precision CNC...PX7080B- SKU:
- PX7080B
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 67.95 MM
- PISTON SIZE METRIC:
- +0.01 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 67.95 MM
- RIDING STYLE:
- OFF-ROAD
MSRP: $132.95Now: $110.00Was: $132.95 -
On Sale
PROX Piston Kit 01.2314.C
PROX
MSRP: $129.95Now: $110.00Was: $129.95A worn or damaged piston is a silent killer of engine performance—it compromises compression, increases blow-by, and can lead to catastrophic failure if left unchecked. The PROX Piston Kit 01.2314.C...PX7080C- SKU:
- PX7080C
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- PISTON DIAMETER METRIC:
- 67.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 67.96 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $129.95Now: $110.00Was: $129.95Qty in Cart: 0Quantity:Price:MSRP: $129.95Now: $110.00Was: $129.95Subtotal: -
On Sale
PROX Piston Kit 01.2314.D
PROX
MSRP: $132.95Now: $110.00Was: $132.95Your engine's power delivery and efficiency depend entirely on piston quality, and worn or damaged pistons directly compromise compression, fuel economy, and reliability. The PROX Piston Kit 01.2314...PX7080D- SKU:
- PX7080D
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE D
- UNITS:
- EACH
- BORE SIZE METRIC:
- 67.97 MM
- PISTON DIAMETER METRIC:
- 67.97 MM
- RIDING STYLE:
- OFF-ROAD
MSRP: $132.95Now: $110.00Was: $132.95
