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
-
PROX Exhaust Valve 28.1654-1
PROX
$56.95Exhaust valve performance directly impacts engine efficiency, combustion temperature management, and overall power delivery. The PROX 28.1654-1 is precision-engineered to OEM specifications, ensuring...09260146- SKU:
- 09260146
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- RIDING STYLE:
- OFF-ROAD
- MATERIAL:
- STEEL
- PRODUCT NAME:
- VALVE
- UNITS:
- EACH
- APPLICATION:
- EXHAUST
$56.95 -
PROX Exhaust Valve 28.3402-1
PROX
$35.95A worn or damaged exhaust valve compromises engine breathing, power delivery, and fuel efficiency—forcing your engine to work harder for less performance. The PROX Exhaust Valve 28.3402-1 restores...09260147- SKU:
- 09260147
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- VALVE
$35.95 -
PROX Exhaust Valve 28.2418-1
PROX
$29.95Exhaust valves are critical to engine breathing and combustion efficiency—a worn or substandard valve directly compromises horsepower, fuel economy, and engine longevity. The PROX 28.2418-1 is...09260148- SKU:
- 09260148
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- APPLICATION:
- EXHAUST
- PRODUCT NAME:
- VALVE
$29.95Qty in Cart: 0Quantity:Price:$29.95Subtotal: -
PROX Intake Valve 28.1495-2
PROX
$25.95Precision valve operation is critical to engine reliability and performance—any deviation in valve geometry directly impacts combustion efficiency and durability. The PROX Intake Valve 28.1495-2 is...09260149- SKU:
- 09260149
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- PRODUCT NAME:
- VALVE
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$25.95 -
PROX Intake Valve 28.1654-2
PROX
$35.95A properly functioning intake valve is critical to your engine's breathing efficiency and power delivery. The PROX 28.1654-2 is precision-manufactured to OEM specifications, ensuring reliable sealing...09260150- SKU:
- 09260150
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- PRODUCT NAME:
- VALVE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$35.95 -
PROX Intake Valve 28.3402-2
PROX
$30.95A worn or damaged intake valve directly compromises cylinder sealing, fuel efficiency, and combustion reliability—issues that cascade into poor engine performance and increased wear on surrounding...09260151- SKU:
- 09260151
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- PRODUCT NAME:
- VALVE
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$30.95 -
PROX Intake Valve 28.2418-3
PROX
$22.95Precision intake valve operation is critical to engine efficiency and reliability—especially under high-performance conditions where tolerances matter. The PROX 28.2418-3 is manufactured to exacting...09260153- SKU:
- 09260153
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PRODUCT NAME:
- VALVE
$22.95 -
PROX Valve Shims - 5 pack 29.748120
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance and overall performance consistency—especially under high-RPM conditions where precision matters most. PROX Valve Shims deliver...09260870- SKU:
- 09260870
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.20 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$10.95 -
PROX Valve Shims - 5 pack 29.748125
PROX
$9.95Valve shim wear directly impacts your engine's valve clearance and overall performance—neglecting this maintenance item can lead to reduced compression, improper combustion timing, and costly engine...09260871- SKU:
- 09260871
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 1.25 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- 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 29.748135
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance and overall performance—letting them degrade compromises both power delivery and engine longevity. PROX Valve Shims give you a...09260873- SKU:
- 09260873
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.35 MM
- RIDING STYLE:
- OFF-ROAD
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
$10.95 -
PROX Valve Shims - 5 pack 29.748140
PROX
$10.95Valve shim wear directly impacts cylinder head performance and engine longevity—replacing worn shims restores proper valve clearance and prevents costly damage to valves, seats, and rocker arms. PROX...09260874- SKU:
- 09260874
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 1.40 MM
$10.95 -
PROX Valve Shims - 5 pack 29.748145
PROX
$10.95Valve shims are critical wear items that directly impact your engine's valve clearance, timing accuracy, and overall performance. Factory shims wear down over time, leading to improper valve overlap...09260875- SKU:
- 09260875
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.45 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shims - 5 pack 29.748150
PROX
$10.95Valve shim wear is a silent killer of engine performance—excessive clearance throws off your valve timing and costs you horsepower you've already paid for. PROX Valve Shims deliver precision-matched...09260876- SKU:
- 09260876
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- WATERCRAFT
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 1.50 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shims - 5 pack 29.748155
PROX
$10.95Valve shim wear directly impacts engine performance and reliability—whether you're chasing lap times or maintaining precise valve clearance on a high-mileage build. PROX Valve Shims deliver...09260877- SKU:
- 09260877
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 1.55 MM
$10.95 -
PROX Valve Shims - 5 pack 29.748160
PROX
$10.95Valve shims are wear items that demand precision—even slight deviations in thickness compromise your valve clearance and can lead to costly engine damage. PROX Valve Shims deliver the exact...09260878- SKU:
- 09260878
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.60 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shims - 5 pack 29.748165
PROX
$10.95Valve shim wear is one of the most common reasons for increased valve lash and loss of performance in high-revving engines. PROX Valve Shims give you precision-machined replacements that cost a...09260879- SKU:
- 09260879
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- VALVE SHIM THICKNESS METRIC:
- 1.65 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
$10.95 -
PROX Valve Shims - 5 pack 29.748170
PROX
$10.95Valve shim wear directly impacts your engine's performance and reliability, making replacement intervals critical for maintaining proper valve clearance and avoiding costly head work. PROX Valve...09260880- SKU:
- 09260880
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.70 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
$10.95 -
PROX Valve Shims - 5 pack 29.748175
PROX
$10.95Valve shim wear directly impacts engine timing and performance—undersized or worn shims cause timing drift, increased valve noise, and potential engine damage. These PROX shims deliver...09260881- SKU:
- 09260881
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.75 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shims - 5 pack 29.748180
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance, compression, and overall performance consistency. These PROX shims deliver precision-machined durability at a fraction of OEM...09260882- SKU:
- 09260882
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 1.80 MM
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
$10.95 -
PROX Valve Shims - 5 pack 29.748185
PROX
$10.95Valve shim wear accelerates with aggressive engine tuning and high-RPM operation, leading to loss of valve clearance and potential engine damage. PROX Valve Shims deliver precision-engineered...09260883- SKU:
- 09260883
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 1.85 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- 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
$10.95
