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 seals engineered to maintain proper compression and...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 seals engineered to maintain proper crankcase pressure...094184- SKU:
- 094184
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
MSRP: $10.95Now: $8.00Was: $10.95 -
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 engineered to restore proper crankshaft sealing and...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 seals for a full crank rebuild, restoring proper...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 gives you everything needed for a complete crank rebuild,...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 contain pressure and eliminate leakage during high-RPM...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 OEM-equivalent seals in one complete package, eliminating...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 for KTM 65 SX includes every seal necessary for a...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 guesswork of sourcing individual seals and ensures your...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: $25.95 -
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 rebuilds by providing all necessary seals in one package,...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 without the guesswork of sourcing individual components...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: $22.95Qty in Cart: 0Quantity:Price:MSRP: $22.95Now: $17.00Was: $22.95Subtotal: -
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 OEM-quality sealing across your Honda engine's critical...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 delivers OEM-equivalent sealing with precision...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 performance and reliability. PROX's comprehensive...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 critical engine surfaces, ensuring reliable compression...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 critical sealing surface meets OEM specifications...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 individual gaskets by bundling all critical sealing...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 performance. PROX's complete gasket kit for Yamaha...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 reliability. Whether you're doing a full overhaul or...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 compromise performance. PROX gasket kits are engineered...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
