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
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On Sale
PROX Top End Gasket Set - Honda 35.1218
PROX
MSRP: $41.95Now: $34.00Was: $41.95A top-end gasket set is essential for maintaining a reliable seal across your cylinder head, ensuring proper combustion pressure and preventing coolant or oil leaks that compromise engine performance. The PROX 35.1218 delivers OEM-equivalent quality at a...09345657- SKU:
- 09345657
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- RIDING STYLE:
- OFF-ROAD
MSRP: $41.95Now: $34.00Was: $41.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1225
PROX
MSRP: $44.05Now: $34.00Was: $44.05A degraded top end gasket set compromises cylinder head seal integrity, leading to coolant leaks, oil seepage, and lost compression—all of which tank performance and reliability. The PROX 35.1225 Top End Gasket Set delivers OEM-equivalent sealing for...09345661- SKU:
- 09345661
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
MSRP: $44.05Now: $34.00Was: $44.05Qty in Cart: 0Quantity:Price:MSRP: $44.05Now: $34.00Was: $44.05Subtotal: -
On Sale
PROX Top End Gasket Set - Honda 35.1227
PROX
MSRP: $88.95Now: $72.00Was: $88.95A quality top-end gasket set is essential for maintaining cylinder head integrity and preventing oil and coolant leaks that compromise engine performance. The PROX 35.1227 delivers OEM-equivalent sealing with precision engineering, ensuring your Honda...09345662- SKU:
- 09345662
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- RIDING STYLE:
- OFF-ROAD
MSRP: $88.95Now: $72.00Was: $88.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1233
PROX
MSRP: $69.95Now: $59.00Was: $69.95A compromised top end gasket set leads to oil leaks, compression loss, and catastrophic engine failure—especially under sustained racing conditions. PROX's 35.1233 gasket set delivers factory-grade sealing with OEM-equivalent materials, ensuring reliable...09345663- SKU:
- 09345663
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- SET
MSRP: $69.95Now: $59.00Was: $69.95Qty in Cart: 0Quantity:Price:MSRP: $69.95Now: $59.00Was: $69.95Subtotal: -
On Sale
PROX Top End Gasket Set - Honda 35.1312
PROX
MSRP: $41.95Now: $34.00Was: $41.95A properly sealed top end is the foundation of reliable engine performance, and PROX gasket sets are engineered to maintain that seal under the demanding conditions of track use and high-RPM operation. This Honda-specific gasket set eliminates the...09345668- SKU:
- 09345668
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- UNITS:
- SET
MSRP: $41.95Now: $34.00Was: $41.95Qty in Cart: 0Quantity:Price:MSRP: $41.95Now: $34.00Was: $41.95Subtotal: -
On Sale
PROX Top End Gasket Set - Honda 35.1325
PROX
MSRP: $39.95Now: $34.00Was: $39.95A properly sealed top end is non-negotiable for engine reliability and peak performance. The PROX Top End Gasket Set delivers OEM-quality sealing with precision-engineered materials that withstand high combustion pressures and thermal cycling. Whether...09345670- SKU:
- 09345670
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- UNITS:
- SET
MSRP: $39.95Now: $34.00Was: $39.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1333
PROX
MSRP: $72.95Now: $59.00Was: $72.95A quality top-end gasket set is essential for maintaining compression integrity and preventing oil leaks that compromise engine performance and reliability. PROX's precision-engineered gasket set ensures proper sealing across all critical combustion...09345671- SKU:
- 09345671
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- RIDING STYLE:
- OFF-ROAD
MSRP: $72.95Now: $59.00Was: $72.95Qty in Cart: 0Quantity:Price:MSRP: $72.95Now: $59.00Was: $72.95Subtotal: -
On Sale
PROX Top End Gasket Set - Honda 35.1334
PROX
MSRP: $88.95Now: $72.00Was: $88.95A top-end gasket set is critical for maintaining cylinder head sealing integrity and preventing coolant and oil leakage that can compromise engine performance and reliability. PROX's 35.1334 gasket set delivers OEM-equivalent durability with precision...09345672- SKU:
- 09345672
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
MSRP: $88.95Now: $72.00Was: $88.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1402
PROX
MSRP: $89.95Now: $76.00Was: $89.95A top-end gasket set is critical for maintaining compression, preventing coolant and oil seepage, and ensuring reliable performance between rebuild cycles. PROX's 35.1402 gasket set delivers OEM-equivalent durability with precision fitment, eliminating...09345677- SKU:
- 09345677
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- PRODUCT NAME:
- GASKET SET
- UNITS:
- SET
MSRP: $89.95Now: $76.00Was: $89.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1409
PROX
MSRP: $41.95Now: $34.00Was: $41.95A top end gasket set is critical to maintaining cylinder head integrity and preventing coolant or oil seepage that compromises engine performance and reliability. The PROX 35.1409 delivers OEM-quality sealing across all top end components, ensuring your...09345681- SKU:
- 09345681
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- SET
MSRP: $41.95Now: $34.00Was: $41.95 -
On Sale
PROX Top End Gasket Set - Yamaha 35.2113
PROX
MSRP: $22.95Now: $17.00Was: $22.95A top-end gasket set is essential maintenance for any high-revving engine—proper sealing prevents coolant and oil leakage that compromises performance and engine longevity. The PROX 35.2113 delivers OEM-equivalent quality at a fraction of dealer pricing,...09345685- SKU:
- 09345685
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
MSRP: $22.95Now: $17.00Was: $22.95Qty in Cart: 0Quantity:Price:MSRP: $22.95Now: $17.00Was: $22.95Subtotal: -
On Sale
PROX Top End Gasket Set - Yamaha 35.2122
PROX
MSRP: $25.95Now: $21.00Was: $25.95A quality top-end gasket set is non-negotiable for any engine rebuild or head service—it's your seal against oil leaks, coolant seepage, and compression loss that compromise performance and reliability. The PROX 35.2122 is engineered to OEM...09345686- SKU:
- 09345686
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- UNITS:
- SET
MSRP: $25.95Now: $21.00Was: $25.95 -
On Sale
PROX Top End Gasket Set - Yamaha 35.2201
PROX
MSRP: $51.95Now: $42.00Was: $51.95A degraded top end gasket set compromises cylinder sealing, leading to compression loss, oil leakage, and reduced engine efficiency. The PROX 35.2201 restores OEM-spec sealing integrity with precision-engineered gaskets designed specifically for Yamaha...09345687- SKU:
- 09345687
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- TYPE:
- TOP END
- PRODUCT NAME:
- GASKET SET
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
MSRP: $51.95Now: $42.00Was: $51.95 -
On Sale
PROX Piston Kit 01.2215.B
PROX
MSRP: $105.95Now: $90.00Was: $105.95Your engine's pistons are the hardworking heart of combustion—and worn or damaged units directly compromise power output, efficiency, and reliability. The PROX Piston Kit 01.2215.B delivers OEM-equivalent performance with precision engineering you can...PX7214B- SKU:
- PX7214B
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- BORE SIZE METRIC:
- 53.95 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- +0.01 MM
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- 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 Piston Kit 01.4223.A
PROX
MSRP: $101.95Now: $87.00Was: $101.95When your engine demands precision and reliability, OEM-spec pistons are non-negotiable. The PROX Piston Kit 01.4223.A delivers factory-matched performance with CNC-machined accuracy, ensuring consistent compression, reduced blow-by, and extended engine...09100024- SKU:
- 09100024
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- BORE SIZE METRIC:
- 53.95 MM
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
MSRP: $101.95Now: $87.00Was: $101.95Qty in Cart: 0Quantity:Price:MSRP: $101.95Now: $87.00Was: $101.95Subtotal: -
On Sale
PROX Piston Kit 01.1414.A
PROX
MSRP: $210.95Now: $167.00Was: $210.95When your engine demands reliability under extreme conditions, OEM-spec pistons aren't optional—they're foundational. The PROX Piston Kit 01.1414.A delivers factory-engineered performance with precision machining that eliminates the guesswork of...09100607- SKU:
- 09100607
- Availability:
- Ships Same Business Day
- Weight:
- 0.81 LBS
- BORE SIZE METRIC:
- 95.96 MM
- PISTON DIAMETER METRIC:
- 95.96 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
MSRP: $210.95Now: $167.00Was: $210.95 -
On Sale
PROX Piston Kit 01.1338.B
PROX
MSRP: $188.95Now: $158.00Was: $188.95Worn or damaged pistons compromise engine efficiency, power delivery, and long-term reliability—especially under racing conditions or high-mileage operation. The PROX Piston Kit 01.1338.B restores your engine to OEM specification with...09101127- SKU:
- 09101127
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 77.98 MM
- BORE SIZE METRIC:
- 77.98 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
MSRP: $188.95Now: $158.00Was: $188.95 -
On Sale
PROX Connecting Rod 03.6520
PROX
MSRP: $210.95Now: $170.00Was: $210.95A connecting rod is the critical link between your crankshaft and piston—it must handle extreme forces without flex or failure. The PROX 03.6520 is engineered to deliver the reliability and precision required for high-RPM performance, whether you're...09230138- SKU:
- 09230138
- Availability:
- Ships Same Business Day
- Weight:
- 1.92 LBS
- MATERIAL:
- FORGED STEEL
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- CONNECTING ROD KIT
- ENGINE TYPE:
- 4-STROKE
- RIDING STYLE:
- ATV
- UNITS:
- EACH
MSRP: $210.95Now: $170.00Was: $210.95 -
On Sale
PROX Connecting Rod 03.4285
PROX
MSRP: $132.95Now: $102.00Was: $132.95A connecting rod is the critical link between your crankshaft and piston—it's where combustion forces transfer into rotational power. The PROX 03.4285 delivers OEM-quality construction with pre-assembled bearings and hardware, eliminating guesswork...09230161- SKU:
- 09230161
- Availability:
- Ships Same Business Day
- Weight:
- 0.76 LBS
- MATERIAL:
- FORGED STEEL
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- CONNECTING ROD KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
MSRP: $132.95Now: $102.00Was: $132.95 -
On Sale
PROX Exhaust Valve 28.1356-1
PROX
MSRP: $30.95Now: $25.00Was: $30.95A precision exhaust valve is critical to maintaining peak combustion efficiency and engine reliability, especially in high-performance applications where tolerances matter. The PROX 28.1356-1 is engineered to OEM specifications, ensuring proper sealing...09260673- SKU:
- 09260673
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- VALVE
MSRP: $30.95Now: $25.00Was: $30.95
