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!
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On Sale
PROX Crankshaft Bearing/Seal Kit - KTM 23.CBS64007
PROX
MSRP: $169.95Now: $136.00Was: $169.95A worn crankshaft bearing or degraded seal compromises engine reliability and can lead to catastrophic damage if left unaddressed. The PROX Crankshaft Bearing/Seal Kit restores OEM-specification performance with factory-engineered components, ensuring...09240708- SKU:
- 09240708
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
MSRP: $169.95Now: $136.00Was: $169.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Husaberg/Husqvarna/KTM 23.CBS64012
PROX
MSRP: $95.95Now: $76.00Was: $95.95A crankshaft bearing and seal kit is essential maintenance for keeping your engine reliable through demanding riding conditions. ProX's OEM-specification design ensures your crankshaft operates with minimal friction and maximum protection against...09240709- SKU:
- 09240709
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
MSRP: $95.95Now: $76.00Was: $95.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Gas-Gas/Husqvarna/KTM 23.CBS64016
PROX
MSRP: $169.95Now: $136.00Was: $169.95A crankshaft bearing and seal kit is essential maintenance for keeping your two-stroke engine running at peak performance and reliability. Over time, factory bearings wear and seals degrade, allowing oil leakage and contamination that compromise...09240710- SKU:
- 09240710
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
MSRP: $169.95Now: $136.00Was: $169.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Beta 23.CBS73013
PROX
MSRP: $73.95Now: $59.00Was: $73.95Engine longevity depends on precision bearing and seal integrity—factory-spec replacements prevent premature wear, oil leakage, and catastrophic failure. The PROX 23.CBS73013 kit delivers OEM-quality components at a fraction of dealer pricing, ideal for...09240711- SKU:
- 09240711
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
MSRP: $73.95Now: $59.00Was: $73.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Beta 23.CBS73022
PROX
MSRP: $123.95Now: $99.00Was: $123.95Crankshaft bearing and seal failure doesn't just sideline your engine—it can cause catastrophic internal damage that costs thousands to repair. The PROX Crankshaft Bearing/Seal Kit (Beta 23.CBS73022) restores your crankshaft assembly to OEM...09240712- SKU:
- 09240712
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
MSRP: $123.95Now: $99.00Was: $123.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Beta 23.CBS73050
PROX
MSRP: $106.95Now: $85.00Was: $106.95A crankshaft bearing and seal failure can sideline your engine when you can least afford it. The PROX 23.CBS73050 kit delivers OEM-spec replacement bearings and seals manufactured to exact factory tolerances, ensuring your crankshaft assembly maintains...09240713- SKU:
- 09240713
- Availability:
- Ships Same Business Day
- Weight:
- 1.36 LBS
MSRP: $106.95Now: $85.00Was: $106.95 -
On Sale
PROX Water Pump Rebuild Kit - Honda 57.1417
PROX
MSRP: $57.95Now: $47.00Was: $57.95Water pump failure can sideline your Honda when you need it most, leaving you stranded with expensive downtime and potential engine damage. The PROX 57.1417 Rebuild Kit delivers a complete, cost-effective solution to restore your pump to factory...09347755- SKU:
- 09347755
- Availability:
- Ships Same Business Day
- Weight:
- 0.18 LBS
MSRP: $57.95Now: $47.00Was: $57.95 -
On Sale
PROX Water Pump Rebuild Kit - Kawasaki 57.4327
PROX
MSRP: $57.95Now: $47.00Was: $57.95Water pump failure can sideline your Kawasaki mid-season, but a full rebuild extends component life and restores cooling system reliability without replacing the entire assembly. This PROX kit delivers all necessary seals, bearings, and gaskets in one...09347756- SKU:
- 09347756
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
MSRP: $57.95Now: $47.00Was: $57.95 -
On Sale
PROX Water Pump Rebuild Kit - Husqvarna/KTM 57.6327
PROX
MSRP: $46.95Now: $38.00Was: $46.95A failing water pump doesn't just compromise cooling efficiency—it puts your entire engine at risk. The PROX Water Pump Rebuild Kit for Husqvarna and KTM machines gives you a complete, cost-effective solution to restore pump performance without replacing...09347757- SKU:
- 09347757
- Availability:
- Ships Same Business Day
- Weight:
- 0.28 LBS
MSRP: $46.95Now: $38.00Was: $46.95 -
On Sale
PROX Water Pump Rebuild Kit - KTM 57.6407
PROX
MSRP: $41.95Now: $34.00Was: $41.95A failing water pump can leave you stranded mid-race or trail, compromising engine cooling when you need it most. This PROX rebuild kit restores your water pump to OEM specifications without the cost and downtime of replacement, giving you peace of mind...09347758- SKU:
- 09347758
- Availability:
- Ships Same Business Day
- Weight:
- 0.19 LBS
MSRP: $41.95Now: $34.00Was: $41.95 -
On Sale
PROX Water Pump Rebuild Kit - Husqvarna/KTM 57.6416
PROX
MSRP: $67.95Now: $55.00Was: $67.95A failing water pump can spell disaster for your engine—overheating, catastrophic damage, and expensive downtime. The PROX Water Pump Rebuild Kit gives you a straightforward way to restore cooling system integrity without replacing the entire pump...09347759- SKU:
- 09347759
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
MSRP: $67.95Now: $55.00Was: $67.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1352
PROX
MSRP: $93.95Now: $76.00Was: $93.95A top-end rebuild demands precision sealing—any leak compromises compression and power output. The PROX 35.1352 Gasket Set delivers complete coverage for Honda applications, engineered to OEM specifications and manufactured to ProX's rigorous quality...09347760- SKU:
- 09347760
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
MSRP: $93.95Now: $76.00Was: $93.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1421
PROX
MSRP: $93.95Now: $76.00Was: $93.95A top-end rebuild demands precision sealing—any leak or gasket failure undermines engine reliability and performance. The PROX 35.1421 gasket set delivers OEM-grade sealing surfaces manufactured to exact specifications, ensuring your Honda engine...09347761- SKU:
- 09347761
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
MSRP: $93.95Now: $76.00Was: $93.95 -
On Sale
PROX Top End Gasket Set - Honda 35.1423
PROX
MSRP: $93.95Now: $76.00Was: $93.95A degraded top-end gasket set compromises compression, invites oil seepage, and forces your engine to work harder than it should. The PROX 35.1423 delivers complete sealing integrity across all top-end interfaces, restoring lost performance and...09347762- SKU:
- 09347762
- Availability:
- Ships Same Business Day
- Weight:
- 0.21 LBS
MSRP: $93.95Now: $76.00Was: $93.95 -
On Sale
PROX Top End Gasket Set - Yamaha 35.2450
PROX
MSRP: $72.95Now: $59.00Was: $72.95A top-end rebuild demands precision—gasket failure introduces oil leaks, compression loss, and costly engine damage. The PROX 35.2450 Top End Gasket Set delivers the complete complement of OEM-spec gaskets required for a proper Yamaha engine overhaul,...09347764- SKU:
- 09347764
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
MSRP: $72.95Now: $59.00Was: $72.95 -
On Sale
PROX Top End Gasket Set - Yamaha 35.2453
PROX
MSRP: $88.95Now: $72.00Was: $88.95A top-end rebuild demands precision sealing—any leak or gasket failure compromises compression and performance. The PROX Top End Gasket Set delivers OEM-equivalent quality at a fraction of the cost, manufactured to exacting specifications so you can...09347765- SKU:
- 09347765
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
MSRP: $88.95Now: $72.00Was: $88.95 -
On Sale
PROX Top End Gasket Set - Suzuki 35.3349
PROX
MSRP: $72.95Now: $59.00Was: $72.95A top-end rebuild demands precision sealing—any leak or gap compromises combustion efficiency and reliability. The PROX Top End Gasket Set for Suzuki engines delivers OEM-grade sealing with ProX's quality control standards, ensuring your rebuild holds...09347767- SKU:
- 09347767
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
MSRP: $72.95Now: $59.00Was: $72.95 -
On Sale
PROX Top End Gasket Set - Kawasaki 35.4350
PROX
MSRP: $78.95Now: $64.00Was: $78.95A top-end rebuild demands precision sealing—any leak compromises compression, power delivery, and engine longevity. The PROX Top End Gasket Set delivers OEM-equivalent sealing performance with materials engineered to handle sustained high RPM and thermal...09347768- SKU:
- 09347768
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
MSRP: $78.95Now: $64.00Was: $78.95 -
On Sale
PROX Top End Gasket Set - Kawasaki 35.4431
PROX
MSRP: $99.95Now: $81.00Was: $99.95A failed top-end gasket can compromise compression, cause oil seepage, and force an incomplete rebuild. The PROX 35.4431 gasket set delivers precision-engineered components that seal reliably and restore your Kawasaki engine to factory specifications...09347770- SKU:
- 09347770
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
MSRP: $99.95Now: $81.00Was: $99.95 -
On Sale
PROX Top End Gasket Set - Gas Gas/Husqvarna/KTM 35.6320
PROX
MSRP: $57.95Now: $47.00Was: $57.95A leaking or degraded top-end gasket set compromises compression, fuel efficiency, and overall engine reliability. Whether you're rebuilding after high-mileage wear or freshening an engine for peak performance, the PROX Top End Gasket Set delivers the...09347771- SKU:
- 09347771
- Availability:
- Ships Same Business Day
- Weight:
- 0.14 LBS
MSRP: $57.95Now: $47.00Was: $57.95
