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 sealing, reduced blowby, and consistent combustion across the...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 02.1315 delivers OEM-grade engineering with the precision...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 replacement, delivering the precision fit and...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 through precision Japanese manufacturing, ensuring your...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 high-silicon aluminum construction that meets or exceeds...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 delivers OEM-equivalent quality without the OEM price...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 restores your engine to factory specifications—or...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 Japanese manufacturing precision, ensuring reliable...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 Japanese-engineered precision, ensuring reliable power delivery and...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 delivers OEM-equivalent construction with precision...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 failure. The PROX Piston Kit 01.3220.C delivers...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 engineering that restores your engine to factory...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 components built to withstand demanding conditions. This...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 your engine maintains peak compression and combustion...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 to OEM specifications. The PROX Piston Kit 01.3320.A...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 performance with precision Japanese manufacturing, ensuring...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 precision manufacturing that ensures consistent ring sealing,...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 machining, this Japanese-manufactured kit delivers the...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 is an OEM-quality replacement engineered to restore...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.D delivers OEM-specification performance with Japanese...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
