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 Gasket Kit - Complete - KTM 34.6420
PROX
MSRP: $214.95Now: $183.00Was: $214.95A complete gasket kit is essential for any engine rebuild or top-end service on your KTM, ensuring proper sealing across all critical engine interfaces. Using OEM-equivalent gaskets prevents compression leaks, oil seepage, and potential engine damage...09345641- SKU:
- 09345641
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
MSRP: $214.95Now: $183.00Was: $214.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1070
PROX
MSRP: $25.95Now: $21.00Was: $25.95A properly sealed top end is non-negotiable for consistent power delivery and engine longevity. The PROX Top End Gasket Set delivers OEM-equivalent sealing without the premium price tag, making it the smart choice for rebuild projects and high-mileage...09345650- SKU:
- 09345650
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- SET
MSRP: $25.95Now: $21.00Was: $25.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1112
PROX
MSRP: $25.95Now: $21.00Was: $25.95A compromised top end gasket set is one of the fastest ways to lose compression, leak oil, and invite catastrophic engine failure. PROX's top end gasket set for Honda applications delivers OEM-equivalent sealing performance with the reliability you need...09345652- SKU:
- 09345652
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- RIDING STYLE:
- OFF-ROAD
MSRP: $25.95Now: $21.00Was: $25.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1115
PROX
MSRP: $25.95Now: $21.00Was: $25.95A compromised top end gasket set will leak oil, reduce compression, and compromise engine reliability—especially critical if you're pushing your Honda to the limit on track or street. PROX's 35.1115 gasket set delivers OEM-equivalent sealing without the...09345654- SKU:
- 09345654
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
MSRP: $25.95Now: $21.00Was: $25.95 -
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 35.1227
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 35.1312
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: $41.95 -
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 35.1334
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 - 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 01.1414.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 -
On Sale
PROX Intake Valve 28.1356-2
PROX
MSRP: $22.95Now: $17.00Was: $22.95A quality intake valve is critical to your engine's breathing efficiency and combustion reliability. The PROX 28.1356-2 is precision-manufactured to strict OEM specifications, ensuring consistent performance and longevity whether you're running a stock...09260674- SKU:
- 09260674
- Availability:
- Ships Same Business Day
- Weight:
- 0.09 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- VALVE
- UNITS:
- EACH
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX Connecting Rod 03.6323
PROX
MSRP: $132.95Now: $102.00Was: $132.95A connecting rod is the critical mechanical link between your piston and crankshaft—any weakness here directly translates to power loss, unreliable shifts, or catastrophic engine failure. The PROX 03.6323 is a complete assembly engineered for durability...09230173- SKU:
- 09230173
- Availability:
- Ships Same Business Day
- Weight:
- 0.99 LBS
- ENGINE TYPE:
- 2-STROKE
- MATERIAL:
- FORGED STEEL
- PRODUCT NAME:
- CONNECTING ROD KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- STREET
- UNITS:
- EACH
MSRP: $132.95Now: $102.00Was: $132.95 -
On Sale
PROX Connecting Rod 03.3323
PROX
MSRP: $132.95Now: $102.00Was: $132.95A connecting rod is the critical link between your piston and crankshaft—any weakness here directly compromises power delivery, reliability, and engine longevity. The PROX 03.3323 is engineered for those who demand precision under load, with...09230185- SKU:
- 09230185
- Availability:
- Ships Same Business Day
- Weight:
- 1.02 LBS
- UNITS:
- EACH
- ENGINE TYPE:
- 2-STROKE
- MATERIAL:
- FORGED STEEL
- PRODUCT NAME:
- CONNECTING ROD KIT
- RIDING STYLE:
- OFF-ROAD
MSRP: $132.95Now: $102.00Was: $132.95
