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 Valve Shim - 5 pack 29.948235
PROX
$10.95Valve shimming is critical to maintaining precise valve clearances and preventing unwanted wear on your cylinder head. These PROX shims are precision-machined to exact tolerances, ensuring consistent performance across your entire valvetrain. With...09260965- SKU:
- 09260965
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.35 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948240
PROX
$10.95Valve shim clearance is critical to engine performance and longevity—even slight deviations compromise timing and increase wear on critical components. PROX Valve Shims are precision-machined to exact tolerances and heat-treated for superior hardness,...09260966- SKU:
- 09260966
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.40 MM
- 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:
- 9.48 MM
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shim - 5 pack 29.948245
PROX
$10.95Valve shimming is critical to maintaining proper valve clearance and preventing catastrophic engine damage from valve float or seat wear. These PROX shims are precision-machined to exact tolerances and heat-treated for superior hardness, ensuring...09260967- SKU:
- 09260967
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 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:
- 2.45 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948250
PROX
$10.95Valve shims are critical wear items in high-performance engines, and precision tolerances directly impact valve timing, lift, and overall engine reliability. The PROX Valve Shim 5-pack ensures consistent performance across multiple shim changes without...09260968- SKU:
- 09260968
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- VALVE SHIM THICKNESS METRIC:
- 2.50 MM
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shim - 5 pack 29.948255
PROX
$9.95Valve shim clearance directly impacts your engine's efficiency and longevity—improper spacing leads to valve float, compression loss, and potential catastrophic failure. PROX Valve Shims are precision-machined to exact tolerances and heat-treated for...09260969- SKU:
- 09260969
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.55 MM
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948260
PROX
$9.95Valve shim wear directly impacts your engine's compression ratio, valve clearance, and overall performance consistency. These PROX shims maintain precise tolerances through repeated thermal cycles, eliminating the performance drift that comes with...09260970- SKU:
- 09260970
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.60 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948265
PROX
$10.95Valve timing precision directly impacts your engine's power delivery and reliability—even micron-level inconsistencies compound into performance loss and premature wear. PROX valve shims are heat-treated to withstand extreme combustion pressures and...09260971- SKU:
- 09260971
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.65 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948270
PROX
$9.95Valve shim clearance directly impacts engine compression, valve timing precision, and overall reliability—especially under high-RPM conditions. PROX Valve Shims are precision-machined to exact tolerances, eliminating guesswork during top-end rebuilds and...09260972- SKU:
- 09260972
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.70 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948275
PROX
$10.95Valve shim clearance is critical to engine reliability and performance—get it wrong, and you're risking bent valves, poor sealing, and costly damage. PROX Valve Shims are precision-machined to exact tolerances and heat-treated for superior hardness,...09260973- SKU:
- 09260973
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.75 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948285
PROX
$10.95Valve shim selection directly impacts your engine's valve clearance, combustion efficiency, and component longevity. The PROX Valve Shim 5-pack delivers precision-engineered shims with heat-treated hardness to minimize wear and maintain tight tolerances...09260975- SKU:
- 09260975
- 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
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.85 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948290
PROX
$10.95Valve shim clearance directly impacts engine performance, combustion efficiency, and component longevity. PROX Valve Shims are precision-machined to exact tolerances, eliminating guesswork during valve adjustment and ensuring consistent performance...09260976- SKU:
- 09260976
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 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
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 2.90 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
$10.95 -
PROX Valve Shim - 5 pack 29.948320
PROX
$9.95Valve shim clearance directly impacts engine longevity and performance consistency—improper shim specifications lead to valve float, reduced compression, and catastrophic engine damage. PROX Valve Shims are precision-machined to exact tolerances and...09260982- SKU:
- 09260982
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 3.20 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948350
PROX
$9.95Valve shim selection directly impacts your engine's valve train geometry and performance characteristics. These PROX shims are precision-machined to exacting tolerances, ensuring accurate valve clearance adjustments without the guesswork. With...09260988- SKU:
- 09260988
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 3.50 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 Kit 29.VSA1000
PROX
$99.95Valve shims are critical wear items that directly impact valve clearance, combustion efficiency, and engine longevity. OEM replacements come with premium pricing and extended lead times—the PROX Valve Shim Kit 29.VSA1000 delivers precision-matched...09260989- SKU:
- 09260989
- Availability:
- Ships Same Business Day
- Weight:
- 0.67 LBS
- OUTSIDE DIAMETER METRIC:
- 10.00 MM
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 1.85 MM - 3.20 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- KIT
$99.95 -
PROX Valveshim - 10.00 x 2.15 - 5 pack 29.100215
PROX
$9.95Valve shim adjustment is critical to engine performance, and worn or incorrect shims compromise compression, valve timing, and overall reliability. The PROX Valveshim 10.00 x 2.15 delivers precision-engineered replacement shims at a fraction of OEM cost,...09260996- SKU:
- 09260996
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 10.00 MM
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.15 MM
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- UNITS:
- 5 PACK
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 10.00 x 2.20 - 5 pack 29.100220
PROX
$9.95Valve shims are critical wear components that directly impact your engine's valvetrain precision and longevity. OEM replacements are expensive and require frequent servicing—PROX valveshims deliver OEM-equivalent performance at a fraction of the cost,...09260997- SKU:
- 09260997
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 10.00 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.20 MM
- PRODUCT NAME:
- SHIM KIT
- UNITS:
- 5 PACK
$9.95 -
PROX Valveshim - 10.00 x 2.25 - 5 pack 29.100225
PROX
$9.95Valve shimming is critical to maintaining proper valve clearance and engine performance, and worn or incorrect shims lead to costly damage and downtime. PROX Valveshims are precision-engineered replacements that restore your engine to OEM specifications...09260998- SKU:
- 09260998
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 10.00 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.25 MM
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 10.00 x 2.30 - 5 pack 29.100230
PROX
$9.95Valve shim wear directly impacts your engine's valve clearance and overall performance—neglecting worn shims leads to improper valve timing and potential engine damage. PROX Valveshims offer a precision-engineered replacement that restores factory...09260999- SKU:
- 09260999
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.30 MM
- OUTSIDE DIAMETER METRIC:
- 10.00 MM
- RIDING STYLE:
- STREET
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 10.00 x 2.35 - 5 pack 29.100235
PROX
$9.95Valve shim replacement is a critical maintenance task for high-performance engines, and OEM shims come with premium price tags that add up quickly across multiple cylinders. The PROX Valveshim 10.00 x 2.35 delivers precision-engineered durability at a...09261000- SKU:
- 09261000
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- STREET
- UNITS:
- 5 PACK
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 2.35 MM
- OUTSIDE DIAMETER METRIC:
- 10.00 MM
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 10.00 x 2.40 - 5 pack 29.100240
PROX
$9.95Valve shims are wear items that demand precision and reliability—improper thickness throws off your valve clearance and compromises engine performance. PROX Valveshims deliver exact OEM dimensions at a fraction of the cost, with heat-treated hardness...09261001- SKU:
- 09261001
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- STREET
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.40 MM
- OUTSIDE DIAMETER METRIC:
- 10.00 MM
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal:
