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 Water Pump Rebuild Kit - Kawasaki 57.4429
PROX
$36.95A failing water pump doesn't just risk overheating—it threatens catastrophic engine damage and costly downtime. The PROX Water Pump Rebuild Kit gives you a straightforward way to restore cooling...09347060- SKU:
- 09347060
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- PRODUCT NAME:
- REPAIR KIT
$36.95Qty in Cart: 0Quantity:Price:$36.95Subtotal: -
PROX Water Pump Rebuild Kit 57.6316
PROX
$39.95A failing water pump can leave you stranded mid-race or destroy an engine in minutes. The PROX Water Pump Rebuild Kit 57.6316 gives you OEM-quality restoration without the cost of replacing the...09347072- SKU:
- 09347072
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- REPAIR KIT
- TYPE:
- WATER PUMP
- UNITS:
- KIT
$39.95Qty in Cart: 0Quantity:Price:$39.95Subtotal: -
PROX Water Pump Rebuild Kit 57.6321
PROX
$39.95A failing water pump doesn't just risk overheating—it compromises engine reliability and performance when you need it most. The PROX Water Pump Rebuild Kit 57.6321 gives you OEM-quality seals,...09347074- SKU:
- 09347074
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- PRODUCT NAME:
- REPAIR KIT
$39.95Qty in Cart: 0Quantity:Price:$39.95Subtotal: -
PROX Water Pump Rebuild Kit 57.6324
PROX
$41.95A failing water pump doesn't just compromise cooling efficiency—it puts your entire engine at risk of catastrophic overheating. The PROX Water Pump Rebuild Kit 57.6324 gives you OEM-quality seals,...09347077- SKU:
- 09347077
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- REPAIR KIT
- TYPE:
- WATER PUMP
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$41.95Qty in Cart: 0Quantity:Price:$41.95Subtotal: -
PROX Water Pump Rebuild Kit 57.6325
PROX
$24.95A failing water pump doesn't just compromise cooling efficiency—it threatens catastrophic engine damage under racing conditions or extended use. The PROX Water Pump Rebuild Kit 57.6325 restores your...09347078- SKU:
- 09347078
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- REPAIR KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- TYPE:
- WATER PUMP
$24.95Qty in Cart: 0Quantity:Price:$24.95Subtotal: -
PROX Top End Gasket Set - Yamaha 35.2018
PROX
$30.95A top-end gasket set is critical for maintaining compression integrity and preventing coolant or oil seepage in your engine's most vulnerable areas. Whether you're rebuilding after a race season or...09347121- SKU:
- 09347121
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- GASKET SET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- SET
$30.95 -
PROX Valve and Spring Kit 28.SES6351-1
PROX
$149.95If you're pushing your engine to the limit, factory valve components simply won't cut it. The PROX Valve and Spring Kit 28.SES6351-1 replaces worn OEM valves and springs with nitrided steel valves...09262726- SKU:
- 09262726
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- SPRING KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- MATERIAL:
- STEEL
- TYPE:
- VALVE
$149.95Qty in Cart: 0Quantity:Price:$149.95Subtotal: -
PROX Valve and Spring Kit 28.SES6353-1
PROX
$149.95If you're pushing your engine beyond stock limits, OEM valves and springs will become your bottleneck. The PROX 28.SES6353-1 Kit replaces those weak points with nitrided steel valves and premium...09262727- SKU:
- 09262727
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- UNITS:
- KIT
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- SPRING KIT
$149.95Qty in Cart: 0Quantity:Price:$149.95Subtotal: -
PROX Valve and Spring Kit 28.SIS6351-2
PROX
$149.95If you're pushing your engine to its limits, OEM valves and springs will hold you back. The PROX 28.SIS6351-2 Kit replaces factory components with nitrided steel valves and premium chrome vanadium...09262730- SKU:
- 09262730
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- PRODUCT NAME:
- VALVE AND SPRING KIT
- APPLICATION:
- INTAKE
- TYPE:
- VALVE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$149.95Qty in Cart: 0Quantity:Price:$149.95Subtotal: -
PROX Valve and Spring Kit 28.SIS6353-2
PROX
$149.95If you're running high RPM or pushing your engine beyond stock parameters, OEM valves and springs become the weak link in your valve train. The PROX 28.SIS6353-2 Kit replaces them with nitrided steel...09262731- SKU:
- 09262731
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- TYPE:
- VALVE
- PRODUCT NAME:
- VALVE AND SPRING KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$149.95Qty in Cart: 0Quantity:Price:$149.95Subtotal: -
PROX Valve Shims - 5 pack 29.748130
PROX
$9.95Valve shim wear is one of the most overlooked maintenance items that directly impacts engine performance and longevity. PROX Valve Shims deliver precision-machined replacement solutions at a fraction...09260872- SKU:
- 09260872
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 1.30 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shims - 5 pack 29.748200
PROX
$9.95Valve shim wear is a silent killer of engine efficiency—when your shims degrade, you lose precise valve timing and risk costly damage to your head. PROX Valve Shims deliver OEM-level performance at a...09260886- SKU:
- 09260886
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 2.00 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shims - 5 pack 29.748255
PROX
$9.95Valve shim replacement is inevitable maintenance for high-revving engines, and OEM options can drain your budget fast. PROX Valve Shims deliver precision-engineered durability at a fraction of OEM...09260897- SKU:
- 09260897
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.55 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shims - 5 pack 29.748300
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance, compression, and overall performance consistency—especially under high-RPM conditions. PROX Valve Shims deliver precision-machined...09260906- SKU:
- 09260906
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 3.00 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$10.95 -
PROX Valve Shims - 5 pack 29.748305
PROX
$9.95Valve shim wear directly impacts cylinder head performance and engine reliability—these precision-machined shims maintain exact valve clearances without the cost of OEM replacements. PROX shims are...09260907- SKU:
- 09260907
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 3.05 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shims - 5 pack 29.748315
PROX
$9.95Valve shim wear directly impacts engine timing and performance—especially in high-RPM applications where tolerances are critical. PROX Valve Shims deliver precision replacements that restore proper...09260909- SKU:
- 09260909
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 3.15 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948120
PROX
$9.95Valve shim selection directly impacts your engine's valvetrain precision and longevity. PROX Valve Shims are heat-treated to maintain hardness under extreme operating conditions, reducing wear and...09260942- SKU:
- 09260942
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 1.20 MM
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948130
PROX
$9.95Valve shimming is critical for maintaining precise valve clearances, and worn or improperly sized shims will cause lost compression, increased noise, and accelerated wear on your valve train. The...09260944- SKU:
- 09260944
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 1.30 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948135
PROX
$9.95Valve shims are critical components in high-performance engine builds, directly affecting valve clearance, lift characteristics, and overall engine responsiveness. PROX valve shims are...09260945- SKU:
- 09260945
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 1.35 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948150
PROX
$10.95Valve shim adjustments are critical to maintaining proper valve clearance and preventing catastrophic engine damage—this 5-pack ensures you have spares on hand for tuning or replacement. PROX valve...09260948- SKU:
- 09260948
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 1.50 MM
- RIDING STYLE:
- WATERCRAFT
$10.95
