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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PROX Top End Gasket Set - Yamaha 35.2448
PROX
$72.95A top-end gasket set is essential for maintaining proper compression and preventing fluid leaks between cylinder head components—critical for consistent performance and reliability whether you're on the track or the trail. PROX's precision-engineered...09347131- SKU:
- 09347131
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PRODUCT NAME:
- GASKET SET
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- TYPE:
- TOP END
$72.95Qty in Cart: 0Quantity:Price:$72.95Subtotal: -
PROX Top End Gasket Set - Yamaha 35.2661
PROX
$99.95A top-end gasket set is critical to maintaining compression integrity and preventing oil seepage in high-stress engine environments. Whether you're rebuilding after a track session or performing routine maintenance, quality gaskets ensure a proper seal...09347133- SKU:
- 09347133
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- ATV
- TYPE:
- TOP END
- RIDING STYLE:
- UTV
- UNITS:
- SET
$99.95 -
PROX Top End Gasket Set - Yamaha 35.2706
PROX
$105.95A quality top-end gasket set is essential for maintaining compression, preventing coolant and oil seepage, and ensuring reliable engine performance during high-demand riding. The PROX 35.2706 delivers OEM-equivalent sealing integrity with...09347134- SKU:
- 09347134
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- ATV
- TYPE:
- TOP END
- UNITS:
- SET
$105.95 -
PROX Top End Gasket Set - Suzuki 35.3001
PROX
$22.95A compromised top end gasket set forces you to choose between a leaking engine and expensive downtime—neither is acceptable when you're chasing performance. PROX's OEM-equivalent gasket set delivers reliable sealing for Suzuki applications, eliminating...09347135- SKU:
- 09347135
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- ATV
- TYPE:
- TOP END
- UNITS:
- SET
$22.95 -
PROX Top End Gasket Set - Kawasaki 35.4317
PROX
$79.95A top-end gasket set is critical for maintaining proper compression and preventing oil leakage in your engine's combustion chamber and valve cover areas. The PROX 35.4317 delivers OEM-equivalent sealing performance with materials engineered to withstand...09347138- SKU:
- 09347138
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- SET
$79.95Qty in Cart: 0Quantity:Price:$79.95Subtotal: -
PROX Top End Gasket Set - Kawasaki 35.4426
PROX
$94.95A top-end gasket set is essential maintenance for any Kawasaki engine experiencing high mileage or preparing for a rebuild. Worn gaskets compromise compression, increase blow-by, and can lead to coolant or oil seepage that degrades performance and...09347139- SKU:
- 09347139
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- PRODUCT NAME:
- GASKET SET
- UNITS:
- SET
$94.95Qty in Cart: 0Quantity:Price:$94.95Subtotal: -
PROX Top End Gasket Set - Sea Doo 35.5508
PROX
$82.53A failing top end gasket set compromises your Sea Doo's compression, reliability, and fuel efficiency—leading to costly engine damage if ignored. PROX's OEM-equivalent gasket set restores proper cylinder sealing and prevents coolant or oil leakage...09347143- SKU:
- 09347143
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- WATERCRAFT
- TYPE:
- TOP END
- UNITS:
- SET
$82.53 -
PROX Top End Gasket Set - Sea Doo 35.5512
PROX
$112.68A leaking or worn top end gasket set compromises combustion efficiency and can lead to costly engine damage if left unaddressed. The PROX Top End Gasket Set is engineered to factory specifications, ensuring a reliable seal that restores compression and...09347145- SKU:
- 09347145
- Availability:
- Ships Same Business Day
- Weight:
- 0.36 LBS
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
$112.68 -
PROX Top End Gasket Set 35.6118
PROX
$36.95A quality top-end gasket set is non-negotiable for maintaining compression and preventing oil seepage in your engine. Whether you're rebuilding after a full race season or performing preventive maintenance, the PROX 35.6118 delivers OEM-grade sealing...09347146- SKU:
- 09347146
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
$36.95 -
PROX Top End Gasket Set 35.6315
PROX
$88.95A top-end gasket set is critical for maintaining compression integrity and preventing fluid leaks in your engine's combustion chamber. PROX's 35.6315 gasket set delivers the precision fit and material quality required for reliable performance, whether...09347148- SKU:
- 09347148
- Availability:
- Ships Same Business Day
- Weight:
- 0.16 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
$88.95 -
PROX Top End Gasket Set 35.6316
PROX
$88.95A quality top-end gasket set is critical to maintaining compression, preventing oil seepage, and ensuring reliable engine performance across countless heat cycles. The PROX 35.6316 delivers OEM-equivalent sealing with materials engineered to handle...09347149- SKU:
- 09347149
- Availability:
- Ships Same Business Day
- Weight:
- 0.21 LBS
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- PRODUCT NAME:
- GASKET SET
$88.95 -
PROX Top End Gasket Set 35.6317
PROX
$72.95A properly sealed top end is non-negotiable for engine reliability and performance. The PROX Top End Gasket Set 35.6317 delivers OEM-equivalent sealing integrity with precision manufacturing, preventing coolant and oil leakage that can compromise your...09347150- SKU:
- 09347150
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- PRODUCT NAME:
- GASKET SET
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
$72.95 -
PROX Intake Valve and Spring Kit 28.SIS1340-2
PROX
$155.95If you're running higher RPMs or pushing your engine beyond stock parameters, OEM valve springs will eventually lose their ability to control valve timing under load—leading to float, missed shifts, and catastrophic engine damage. The PROX Intake Valve...09262892- SKU:
- 09262892
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- VALVE AND SPRING KIT
$155.95 -
PROX Valve and Spring Kit 28.SES2414-1
PROX
$155.95If you're pushing your engine to its limits, factory valve and spring assemblies become a liability. The PROX 28.SES2414-1 kit replaces worn OEM components with nitrided steel valves and premium chrome vanadium springs engineered to withstand sustained...09262724- SKU:
- 09262724
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- VALVE AND SPRING KIT
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- UNITS:
- KIT
$155.95Qty in Cart: 0Quantity:Price:$155.95Subtotal: -
PROX Valve and Spring Kit 28.SES2444-1
PROX
$159.95If you're running your engine at sustained high RPM or pushing it beyond stock parameters, OEM valve springs will eventually lose their snap—and valve float becomes a real problem. The PROX Valve and Spring Kit 28.SES2444-1 pairs durable nitrided steel...09262725- SKU:
- 09262725
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- SPRING KIT
- UNITS:
- KIT
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$159.95Qty in Cart: 0Quantity:Price:$159.95Subtotal: -
PROX Valve and Spring Kit 28.SIS2414-2
PROX
$155.95If you're pushing your engine to its limits, OEM valves and springs won't cut it. The PROX 28.SIS2414-2 Kit replaces those weak factory components with nitrided steel valves and premium chrome vanadium springs engineered to handle extreme RPM and...09262728- SKU:
- 09262728
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- PRODUCT NAME:
- VALVE AND SPRING KIT
- UNITS:
- KIT
$155.95Qty in Cart: 0Quantity:Price:$155.95Subtotal: -
PROX Valve and Spring Kit 28.SIS2444-2
PROX
$166.95If you're running high-RPM applications or pushing your engine beyond stock parameters, OEM valve springs will struggle to keep pace with valve float and premature wear. The PROX Valve and Spring Kit 28.SIS2444-2 replaces both intake and exhaust valves...09262729- SKU:
- 09262729
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- PRODUCT NAME:
- VALVE AND SPRING KIT
- UNITS:
- KIT
$166.95 -
PROX Exhaust Valve 28.1334-1
PROX
$40.95Proper valve operation is critical to engine reliability and performance—a compromised exhaust valve leads to lost compression, increased emissions, and potential catastrophic engine damage. The PROX 28.1334-1 is engineered to OEM specifications,...09260143- SKU:
- 09260143
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- PRODUCT NAME:
- VALVE
- UNITS:
- EACH
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- APPLICATION:
- EXHAUST
$40.95 -
PROX Exhaust Valve 28.1402-1
PROX
$40.95Proper valve clearance and sealing are critical to engine performance and longevity—a worn or damaged exhaust valve directly impacts compression, combustion efficiency, and power output. The PROX Exhaust Valve 28.1402-1 is engineered to OEM...09260144- SKU:
- 09260144
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- VALVE
- UNITS:
- EACH
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
$40.95 -
PROX Exhaust Valve 28.1495-1
PROX
$35.95A precision exhaust valve is critical to maintaining proper engine breathing and combustion efficiency, directly impacting power output and engine longevity. The PROX 28.1495-1 is engineered to OEM specifications, ensuring reliable performance whether...09260145- SKU:
- 09260145
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- MATERIAL:
- STEEL
- PRODUCT NAME:
- VALVE
- RIDING STYLE:
- OFF-ROAD
- APPLICATION:
- EXHAUST
$35.95
