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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Wossner Connecting Rod Kit Beta RR 250 2013-2017 P2069
WOSSNER
$122.00A connecting rod kit is critical to engine reliability, especially in high-RPM or competitive riding environments where stock components can fail under sustained stress. The Wossner P2069 is...09230687- SKU:
- 09230687
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
$122.00 -
Wossner Piston Kit 53.96mm Yamaha YZ125 2022-2025 8321DB
WOSSNER
$132.00A worn or damaged piston directly compromises combustion efficiency, throttle response, and engine longevity—especially critical in a high-revving two-stroke like the YZ125. The Wossner 8321DB...09106610- SKU:
- 09106610
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
$132.00 -
On Sale
ATHENA Piston Kit with Gaskets - 77.96 mm - KX250F P5F0780071004A
ATHENA
MSRP: $289.95Now: $225.00Was: $289.95A worn or damaged piston directly impacts combustion efficiency, throttle response, and engine longevity—especially in high-demand off-road conditions. The ATHENA Piston Kit delivers OEM-exceeding...09031739- SKU:
- 09031739
- Availability:
- Ships Same Business Day
- Weight:
- 1.17 LBS
MSRP: $289.95Now: $225.00Was: $289.95 -
On Sale
ATHENA Piston Kit with Gaskets - 77.97 mm - KX250F P5F0780071004B
ATHENA
MSRP: $289.95Now: $225.00Was: $289.95When your stock piston starts showing wear, combustion efficiency drops and power delivery suffers. The ATHENA Piston Kit restores—and exceeds—OE performance with a high-silicon aluminum alloy...09031740- SKU:
- 09031740
- Availability:
- Ships Same Business Day
- Weight:
- 1.18 LBS
MSRP: $289.95Now: $225.00Was: $289.95 -
ACERBIS X-Power Kit - Black - Honda 2983680001
ACERBIS
$76.95Off-road riding exposes your engine to relentless punishment—mud, debris, rocks, and extreme temperatures. The ACERBIS X-Power Kit shields your engine's most vulnerable components with purpose-built...09402161- SKU:
- 09402161
- Availability:
- Ships Same Business Day
- Weight:
- 2.15 LBS
$76.95 -
On Sale
PROX Crankshaft Oil Seal Set - Kawasaki 42.4351
PROX
MSRP: $25.95Now: $21.00Was: $25.95A failing crankshaft oil seal is a silent killer—it allows oil to seep past critical bearing surfaces, risking catastrophic engine damage and costly rebuilds. The PROX Crankshaft Oil Seal Set...09351278- SKU:
- 09351278
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
MSRP: $25.95Now: $21.00Was: $25.95 -
On Sale
PROX Crankshaft Oil Seal Set - Beta 42.7218
PROX
MSRP: $22.95Now: $17.00Was: $22.95Crankshaft oil seals are critical barriers against oil leakage and contamination—worn or failed seals compromise engine efficiency and can lead to costly damage. The PROX 42.7218 set delivers...09351279- SKU:
- 09351279
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX Crankshaft Oil Seal Set - Beta 42.7220
PROX
MSRP: $22.95Now: $17.00Was: $22.95A complete crankshaft rebuild demands precision sealing to prevent oil leakage and maintain engine integrity. The PROX Crankshaft Oil Seal Set delivers OEM-specification components manufactured to...09351280- SKU:
- 09351280
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX Crankshaft Oil Seal Set - Beta 42.7350
PROX
MSRP: $30.95Now: $25.00Was: $30.95A compromised crankshaft seal can lead to catastrophic oil loss and engine damage—especially under high RPM conditions where pressure spikes expose even minor leaks. The PROX Crankshaft Oil Seal Set...09351281- SKU:
- 09351281
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
MSRP: $30.95Now: $25.00Was: $30.95 -
On Sale
PROX Connecting Rod Kit - Honda 03.1363
PROX
MSRP: $173.95Now: $141.00Was: $173.95A connecting rod kit is critical infrastructure for any high-performance Honda engine build—it directly transfers combustion forces from the piston to the crankshaft, making durability and precision...09230694- SKU:
- 09230694
- Availability:
- Ships Same Business Day
- Weight:
- 1.20 LBS
MSRP: $173.95Now: $141.00Was: $173.95 -
On Sale
PROX Connecting Rod Kit - Yamaha 03.2018
PROX
MSRP: $118.95Now: $93.00Was: $118.95A connecting rod failure mid-race or mid-rebuild can derail your entire engine program. The PROX Connecting Rod Kit for Yamaha engines delivers the dimensional precision and material strength needed...09230695- SKU:
- 09230695
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
MSRP: $118.95Now: $93.00Was: $118.95 -
On Sale
PROX Connecting Rod Kit - Yamaha 03.2232
PROX
MSRP: $132.95Now: $102.00Was: $132.95A connecting rod kit is critical for maintaining engine integrity and performance—it directly transfers combustion forces from your pistons to the crankshaft, and a worn or damaged rod can cause...09230696- SKU:
- 09230696
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
MSRP: $132.95Now: $102.00Was: $132.95 -
On Sale
PROX Connecting Rod Kit - Gas Gas | Yamaha 03.2432
PROX
MSRP: $183.95Now: $150.00Was: $183.95A connecting rod is critical to engine reliability—it directly transfers combustion force from the piston to the crankshaft under extreme stress and temperature. PROX's double-forged construction...09230697- SKU:
- 09230697
- Availability:
- Ships Same Business Day
- Weight:
- 1.35 LBS
MSRP: $183.95Now: $150.00Was: $183.95 -
On Sale
PROX Connecting Rod Kit - Husaberg | Husqvarna | KTM 03.6333
PROX
MSRP: $232.95Now: $195.00Was: $232.95A connecting rod is the critical link between your piston and crankshaft—any weakness here directly impacts power delivery, reliability, and engine longevity. The PROX Connecting Rod Kit for...09230699- SKU:
- 09230699
- Availability:
- Ships Same Business Day
- Weight:
- 1.20 LBS
MSRP: $232.95Now: $195.00Was: $232.95 -
On Sale
PROX Connecting Rod Kit - Beta 03.7322
PROX
MSRP: $137.95Now: $110.00Was: $137.95A connecting rod is the critical link between your piston and crankshaft—any weakness here directly compromises power delivery and engine reliability. The PROX Connecting Rod Kit is engineered to OEM...09230702- SKU:
- 09230702
- Availability:
- Ships Same Business Day
- Weight:
- 1.11 LBS
MSRP: $137.95Now: $110.00Was: $137.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Honda 23.CBS14005
PROX
MSRP: $138.95Now: $110.00Was: $138.95A worn crankshaft bearing or compromised seal will rapidly degrade engine performance and reliability. This ProX kit replaces all critical bearing and seal components in one complete package,...09240701- SKU:
- 09240701
- Availability:
- Ships Same Business Day
- Weight:
- 1.15 LBS
MSRP: $138.95Now: $110.00Was: $138.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - KTM 23.CBS60001
PROX
MSRP: $38.95Now: $31.00Was: $38.95A properly sealed crankshaft is fundamental to engine longevity—compromised bearings and worn seals lead to oil starvation and contamination that cascade into catastrophic failure. This ProX kit...09240703- SKU:
- 09240703
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
MSRP: $38.95Now: $31.00Was: $38.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - KTM 23.CBS60009
PROX
MSRP: $41.95Now: $34.00Was: $41.95A worn or damaged crankshaft bearing and seal assembly will compromise engine integrity, reduce performance, and risk catastrophic failure. The PROX Crankshaft Bearing/Seal Kit delivers...09240704- SKU:
- 09240704
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
MSRP: $41.95Now: $34.00Was: $41.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Husaberg/Husqvarna/KTM 23.CBS63013
PROX
MSRP: $187.95Now: $150.00Was: $187.95A compromised crankshaft bearing or seal will quickly degrade engine performance and lead to catastrophic internal damage. The PROX Crankshaft Bearing/Seal Kit supplies all necessary components to...09240705- SKU:
- 09240705
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
MSRP: $187.95Now: $150.00Was: $187.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Husqvarna/KTM 23.CBS63016
PROX
MSRP: $180.95Now: $144.00Was: $180.95Crankshaft bearing and seal failure can compromise engine integrity and sideline your machine at critical moments. This ProX kit delivers OEM-specification components engineered for reliability,...09240706- SKU:
- 09240706
- Availability:
- Ships Same Business Day
- Weight:
- 1.20 LBS
MSRP: $180.95Now: $144.00Was: $180.95
