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 Valveshim - 5 pack 29.890260
PROX
$9.95Valve shims are wear items that demand precision replacement—using undersized or poorly machined shims leads to valve train instability, timing issues, and potential engine damage. PROX Valveshims are precision-machined to exact specifications and...09260940- SKU:
- 09260940
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 2.60 MM
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shim - 5 pack 29.948125
PROX
$9.95Valve shim selection directly impacts your engine's performance, reliability, and tuning precision. These PROX shims are heat-treated to exacting standards, delivering the dimensional consistency required for proper valve clearance management across...09260943- SKU:
- 09260943
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 1.25 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95 -
PROX Valve Shim - 5 pack 29.948140
PROX
$10.95Valve train precision directly impacts engine reliability and performance consistency. PROX Valve Shims are heat-treated and machined to exact tolerances, ensuring proper valve clearance and eliminating unwanted wear on critical engine components. This...09260946- SKU:
- 09260946
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.40 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valve Shim - 5 pack 29.948145
PROX
$10.95Valve shim clearance directly impacts engine timing, power delivery, and component longevity—making precision fitment non-negotiable for serious builders. PROX shims are heat-treated to resist wear and maintain exact tolerances through extended track...09260947- SKU:
- 09260947
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- 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
$10.95 -
PROX Valve Shim - 5 pack 29.948155
PROX
$10.95Valve shimming is critical for maintaining precise valve clearances, and worn or incorrect shims lead to poor combustion timing, reduced power output, and accelerated component wear. The PROX Valve Shim 5-pack delivers precision-machined consistency...09260949- SKU:
- 09260949
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 1.55 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
$10.95 -
PROX Valve Shim - 5 pack 29.948160
PROX
$10.95Valve shim wear directly impacts your engine's compression, valve timing, and overall performance consistency—especially in high-RPM or forced induction applications. This 5-pack of PROX shims gives you the precision adjustments needed to dial in exact...09260950- SKU:
- 09260950
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 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:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.60 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
$10.95 -
PROX Valve Shim - 5 pack 29.948165
PROX
$10.95Valve shim selection directly impacts your engine's precision timing and overall performance reliability. PROX Valve Shims maintain exact clearance tolerances across extended operating cycles, preventing costly valve train wear and potential catastrophic...09260951- SKU:
- 09260951
- 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:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- VALVE SHIM THICKNESS METRIC:
- 1.65 MM
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shim - 5 pack 29.948170
PROX
$10.95Valve shims are critical to maintaining precise valve clearance and ensuring consistent engine performance across heat cycles. Over time, stock shims wear and degrade, leading to increased clearance deviation and potential valve train damage. The PROX...09260952- SKU:
- 09260952
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 1.70 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
$10.95 -
PROX Valve Shim - 5 pack 29.948175
PROX
$10.95Valve shimming is critical to maintaining proper valve clearance and ensuring your engine operates at peak efficiency. These PROX shims are precision-machined to exact tolerances and heat-treated for superior hardness, minimizing wear even under extreme...09260953- SKU:
- 09260953
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 1.75 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
$10.95 -
PROX Valve Shim - 5 pack 29.948180
PROX
$10.95Valve shimming is critical for maintaining precise valve clearances in high-performance and racing engines—even small deviations can compromise power delivery, fuel efficiency, and component longevity. The PROX Valve Shim 5-pack gives you the exact...09260954- SKU:
- 09260954
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 1.80 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valve Shim - 5 pack 29.948185
PROX
$10.95Valve shim selection directly impacts your engine's ability to maintain precise valve clearances under high RPM and extreme heat. PROX Valve Shims deliver the hardness and dimensional accuracy required for sustained performance without degradation,...09260955- SKU:
- 09260955
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 1.85 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:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valve Shim - 5 pack 29.948190
PROX
$10.95Valve shim selection directly impacts your engine's valve clearance accuracy and overall reliability under sustained performance conditions. PROX shims are precision-machined to exacting tolerances, ensuring consistent clearance maintenance across heat...09260956- SKU:
- 09260956
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 1.90 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948195
PROX
$10.95Valve shims are critical for maintaining proper valve clearance and preventing catastrophic engine damage from improper gap settings. This PROX 5-pack ensures you have precision replacements on hand for quick adjustments, whether you're dialing in a...09260957- SKU:
- 09260957
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 1.95 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$10.95 -
PROX Valve Shim - 5 pack 29.948200
PROX
$10.95Valve shim clearance directly impacts your engine's reliability and performance—improper specs lead to valve float, bent pushrods, and catastrophic failure. PROX valve shims are precision-machined to exact tolerances and heat-treated for durability,...09260958- SKU:
- 09260958
- 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:
- 2.00 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- OFF-ROAD
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
$10.95 -
PROX Valve Shim - 5 pack 29.948205
PROX
$10.95Valve shim clearance directly impacts engine efficiency, combustion timing, and component longevity. PROX valve shims are precision-machined to exacting tolerances, eliminating guesswork during valve adjustment and ensuring your engine maintains optimal...09260959- SKU:
- 09260959
- 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:
- 9.48 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.05 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948210
PROX
$10.95Valve shim clearance directly impacts engine performance, combustion efficiency, and component longevity. If your shims are worn or incorrectly sized, you'll experience valve float, compression loss, and potential catastrophic engine damage. PROX valve...09260960- SKU:
- 09260960
- 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
- 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:
- 2.10 MM
$10.95 -
PROX Valve Shim - 5 pack 29.948215
PROX
$10.95Valve train precision directly impacts engine reliability and performance consistency. These PROX shims are heat-treated to resist wear and maintain exact tolerances through countless combustion cycles, ensuring your valvetrain stays dialed in whether...09260961- SKU:
- 09260961
- Availability:
- Ships Same Business Day
- Weight:
- 0.03 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.15 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
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valve Shim - 5 pack 29.948220
PROX
$10.95Valve shim selection directly impacts your engine's valve clearance, compression ratio, and overall top-end performance. PROX Valve Shims are precision-machined to exact tolerances and heat-treated for superior hardness, eliminating premature wear that...09260962- SKU:
- 09260962
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- STREET
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- VALVE SHIM THICKNESS METRIC:
- 2.20 MM
- 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
$10.95 -
PROX Valve Shim - 5 pack 29.948225
PROX
$10.95Valve train geometry directly impacts engine performance, and worn or improperly sized shims compromise both power delivery and component longevity. The PROX Valve Shim 5-pack delivers precision-matched replacements that restore exact valve clearances,...09260963- SKU:
- 09260963
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- VALVE SHIM THICKNESS METRIC:
- 2.25 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$10.95 -
PROX Valve Shim - 5 pack 29.948230
PROX
$10.95Valve shim precision directly impacts engine reliability and performance consistency across your entire powerband. These PROX shims are heat-treated for superior hardness, reducing wear and extending the service life of your valve train. Whether you're...09260964- SKU:
- 09260964
- 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
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- VALVE SHIM THICKNESS METRIC:
- 2.30 MM
$10.95
