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 PRO-X Crank Seal Kit 42.1103
PROX
MSRP: $10.95Now: $8.00Was: $10.95A failing crank seal will compromise your engine's integrity, leading to oil leakage, contamination, and potential catastrophic failure. The PROX PRO-X Crank Seal Kit 42.1103 delivers OEM-quality...094181- SKU:
- 094181
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $10.95Now: $8.00Was: $10.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.1206
PROX
MSRP: $10.95Now: $8.00Was: $10.95A compromised crank seal can lead to oil leakage, loss of compression, and catastrophic engine failure—especially under high-RPM conditions. The PROX PRO-X Crank Seal Kit 42.1206 provides OEM-quality...094184- SKU:
- 094184
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
MSRP: $10.95Now: $8.00Was: $10.95Qty in Cart: 0Quantity:Price:MSRP: $10.95Now: $8.00Was: $10.95Subtotal: -
On Sale
PROX PRO-X Crank Seal Kit 42.1312
PROX
MSRP: $16.95Now: $13.00Was: $16.95A worn or failing crank seal compromises engine integrity, leading to oil leakage, contamination, and potential catastrophic failure. The PROX PRO-X Crank Seal Kit 42.1312 delivers OEM-quality seals...094187- SKU:
- 094187
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $16.95Now: $13.00Was: $16.95 -
On Sale
PROX Crank Seal Kit - CR250/500 42.1304
PROX
MSRP: $10.95Now: $8.00Was: $10.95A worn crank seal compromises compression and invites oil leakage into your combustion chamber—exactly what your CR250 or CR500 doesn't need. This complete PROX Crank Seal Kit delivers OEM-equivalent...09350292- SKU:
- 09350292
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- OIL
- PRODUCT NAME:
- SEAL
MSRP: $10.95Now: $8.00Was: $10.95 -
On Sale
PROX Crank Seal Kit - CRF250R 42.1405
PROX
MSRP: $22.95Now: $17.00Was: $22.95A compromised crank seal leads to oil leakage, contamination, and catastrophic engine failure—especially critical in high-revving 4-stroke applications like the CRF250R. This OEM-quality seal kit...09350294- SKU:
- 09350294
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SEAL
- TYPE:
- OIL
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX Crank Seal Kit - RM250 42.3325
PROX
MSRP: $29.95Now: $25.00Was: $29.95A compromised crankshaft seal leads to catastrophic oil loss and potential engine failure—neither acceptable for track or trail. The PROX Crank Seal Kit delivers OEM-quality seals engineered to...09350315- SKU:
- 09350315
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- TYPE:
- OIL
- PRODUCT NAME:
- SEAL
MSRP: $29.95Now: $25.00Was: $29.95Qty in Cart: 0Quantity:Price:MSRP: $29.95Now: $25.00Was: $29.95Subtotal: -
On Sale
PROX Crank Seal Kit - KTM60/65SX 42.6017
PROX
MSRP: $14.95Now: $13.00Was: $14.95A worn crank seal compromises compression, invites fuel leakage, and accelerates internal engine wear—issues that compound quickly on high-revving two-strokes. The PROX Crank Seal Kit delivers...09350319- SKU:
- 09350319
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- OIL
- RIDING STYLE:
- OFF-ROAD
MSRP: $14.95Now: $13.00Was: $14.95Qty in Cart: 0Quantity:Price:MSRP: $14.95Now: $13.00Was: $14.95Subtotal: -
On Sale
PROX Crank Seal Kit - KTM65SX 42.6029
PROX
MSRP: $22.95Now: $17.00Was: $22.95A complete crank seal kit is essential for any bottom-end rebuild—worn seals compromise compression, invite contamination, and accelerate wear on freshly machined components. The PROX Crank Seal Kit...09350320- SKU:
- 09350320
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- OIL
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX Crank Seal Kit - KTM85SX 42.6103
PROX
MSRP: $25.95Now: $21.00Was: $25.95A compromised crank seal leads to oil leakage, contamination, and catastrophic engine failure—especially critical on high-revving two-strokes like the KTM85SX. This complete seal kit eliminates the...09350321- SKU:
- 09350321
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SEAL
- TYPE:
- OIL
- APPLICATION:
- CRANKSHAFT
MSRP: $25.95Now: $21.00Was: $25.95Qty in Cart: 0Quantity:Price:MSRP: $25.95Now: $21.00Was: $25.95Subtotal: -
On Sale
PROX Crank Seal Kit 42.6218
PROX
MSRP: $16.95Now: $13.00Was: $16.95A compromised crank seal can silently sabotage engine performance through oil leakage, contamination, and loss of critical lubrication. This complete seal kit eliminates guesswork during crank...09350322- SKU:
- 09350322
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- TYPE:
- OIL
- PRODUCT NAME:
- SEAL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
MSRP: $16.95Now: $13.00Was: $16.95 -
On Sale
PROX Crank Seal Kit - KTM250/300 42.6320
PROX
MSRP: $22.95Now: $17.00Was: $22.95A compromised crank seal allows oil to escape and contaminants to enter—both catastrophic for engine longevity. The PROX Crank Seal Kit delivers OEM-spec seals for a complete, reliable crank rebuild...09350323- SKU:
- 09350323
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SEAL
- TYPE:
- OIL
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX Gasket Kit - Complete - Honda 34.1115
PROX
MSRP: $83.95Now: $68.00Was: $83.95A complete gasket kit is foundational to engine reliability—worn or degraded gaskets lead to oil leaks, coolant seepage, and compromised compression that kills performance. The PROX 34.1115 delivers...09345517- SKU:
- 09345517
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- GASKET KIT
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
MSRP: $83.95Now: $68.00Was: $83.95 -
On Sale
PROX Gasket Kit - Complete - Honda 34.1223
PROX
MSRP: $104.95Now: $89.00Was: $104.95A quality gasket kit is the foundation of engine reliability—poor sealing leads to oil leaks, coolant loss, and internal contamination that compromise performance and longevity. The PROX Gasket Kit...09345521- SKU:
- 09345521
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
MSRP: $104.95Now: $89.00Was: $104.95Qty in Cart: 0Quantity:Price:MSRP: $104.95Now: $89.00Was: $104.95Subtotal: -
On Sale
PROX Gasket Kit - Complete - Honda 34.1227
PROX
MSRP: $199.95Now: $170.00Was: $199.95A complete gasket kit is essential maintenance for any Honda engine rebuild or top-end overhaul, ensuring proper sealing across all critical surfaces and preventing costly fluid leaks that compromise...09345523- SKU:
- 09345523
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
- ENGINE TYPE:
- 2-STROKE
MSRP: $199.95Now: $170.00Was: $199.95 -
On Sale
PROX Gasket Kit - Complete - Honda 34.1312
PROX
MSRP: $105.95Now: $85.00Was: $105.95A failed gasket can compromise your engine's integrity and lead to costly coolant leaks, oil seepage, and performance loss. The PROX Gasket Kit – Complete delivers OEM-equivalent sealing across all...09345524- SKU:
- 09345524
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- GASKET KIT
- ENGINE TYPE:
- 4-STROKE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
MSRP: $105.95Now: $85.00Was: $105.95 -
On Sale
PROX Gasket Kit - Complete - Honda 34.1409
PROX
MSRP: $104.95Now: $89.00Was: $104.95A complete gasket kit is the foundation of any reliable engine rebuild or refresh. PROX's comprehensive gasket set eliminates the guesswork of sourcing individual seals and gaskets, ensuring every...09345534- SKU:
- 09345534
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- PRODUCT NAME:
- GASKET KIT
- TYPE:
- COMPLETE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- ENGINE TYPE:
- 2-STROKE
MSRP: $104.95Now: $89.00Was: $104.95Qty in Cart: 0Quantity:Price:MSRP: $104.95Now: $89.00Was: $104.95Subtotal: -
On Sale
PROX Gasket Kit - Complete - Honda 34.1422
PROX
MSRP: $214.95Now: $183.00Was: $214.95A complete gasket kit is foundational to reliable engine sealing—it's the difference between peak performance and catastrophic failure. PROX's Honda 34.1422 kit eliminates the guesswork of sourcing...09345536- SKU:
- 09345536
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
MSRP: $214.95Now: $183.00Was: $214.95Qty in Cart: 0Quantity:Price:MSRP: $214.95Now: $183.00Was: $214.95Subtotal: -
On Sale
PROX Gasket Kit - Complete - Yamaha 34.2218
PROX
MSRP: $72.95Now: $59.00Was: $72.95A complete gasket kit is essential for any engine rebuild or top-end refresh—it ensures proper sealing across all critical surfaces and eliminates the risk of coolant or oil leaks that can compromise...09345546- SKU:
- 09345546
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- UNITS:
- KIT
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
MSRP: $72.95Now: $59.00Was: $72.95 -
On Sale
PROX Gasket Kit - Complete - Yamaha 34.2222
PROX
MSRP: $78.95Now: $64.00Was: $78.95A complete gasket kit is essential for any engine rebuild or top-end service—it ensures a proper seal across all critical joints and prevents oil and coolant leaks that can compromise performance and...09345548- SKU:
- 09345548
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PRODUCT NAME:
- GASKET KIT
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
MSRP: $78.95Now: $64.00Was: $78.95 -
On Sale
PROX Gasket Kit - Complete - Yamaha 34.2225
PROX
MSRP: $99.95Now: $81.00Was: $99.95A complete gasket kit is essential for any engine rebuild or top-end overhaul—it ensures a proper seal across all critical junctures and eliminates the risk of oil leaks or compression loss that can...09345549- SKU:
- 09345549
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
MSRP: $99.95Now: $81.00Was: $99.95
