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 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 replacements at a fraction of OEM pricing, so you can...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 OEM-equivalent precision at a fraction of the replacement cost,...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 dimensions your engine requires, with a proprietary...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 fraction of OEM shims while maintaining the exact...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 Shims deliver OEM-quality precision at a fraction of the...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 precision-machined replacement options that restore OEM...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 replacement costs, making them the smart choice for racers and...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 replacements that restore factory tolerances without the cost...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 -
PROX Valve Shims - 5 pack 29.748190
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance stability, affecting both performance and longevity. PROX Valve Shims deliver precision-machined replacements that restore factory tolerances without the cost of OEM components. This 5-pack...09260884- SKU:
- 09260884
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- VALVE SHIM THICKNESS METRIC:
- 1.90 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
$10.95 -
PROX Valve Shims - 5 pack 29.748195
PROX
$10.95Valve shim wear is one of the most overlooked maintenance issues in high-performance engines, yet it directly impacts valve timing accuracy and overall engine efficiency. These PROX shims are precision-machined to OEM specifications and engineered with...09260885- SKU:
- 09260885
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 1.95 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
$10.95 -
PROX Valve Shims - 5 pack 29.748205
PROX
$10.95Valve shim wear directly impacts your engine's timing precision and overall performance—especially under high-RPM and forced-induction conditions. These PROX shims deliver OEM-equivalent specifications at a fraction of the cost, making them an essential...09260887- SKU:
- 09260887
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 2.05 MM
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valve Shims - 5 pack 29.748210
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance, timing precision, and overall performance—making regular replacement essential for maintaining peak operation. PROX Valve Shims deliver OEM-equivalent precision at a fraction of the cost,...09260888- SKU:
- 09260888
- 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:
- 2.10 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
$10.95 -
PROX Valve Shims - 5 pack 29.748215
PROX
$10.95Valve shim wear directly impacts engine timing and performance—degraded shims lead to increased valve clearance, reduced compression, and potential engine damage. PROX Valve Shims are precision-engineered replacements that restore exact valve clearances...09260889- SKU:
- 09260889
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 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:
- 2.15 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$10.95 -
PROX Valve Shims - 5 pack 29.748220
PROX
$10.95Valve shim wear directly impacts cylinder head performance and engine reliability—worn shims cause valve clearance drift that degrades combustion efficiency and increases risk of valve float at high RPM. The PROX Valve Shims 5-pack (29.748220) delivers...09260890- SKU:
- 09260890
- 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:
- 2.20 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 29.748225
PROX
$9.95Valve shim wear directly impacts valve clearance, timing accuracy, and overall engine performance—especially in high-rpm applications where precision is non-negotiable. The PROX Valve Shims 5-pack offers a cost-effective alternative to expensive OEM...09260891- SKU:
- 09260891
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- VALVE SHIM THICKNESS METRIC:
- 2.25 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$9.95 -
PROX Valve Shims - 5 pack 29.748230
PROX
$9.95Valve shim wear directly impacts your engine's valve clearance, timing precision, and overall performance—and replacing worn OEM shims can cost a fortune. PROX Valve Shims deliver factory-spec accuracy at a fraction of the price, with precision machining...09260892- SKU:
- 09260892
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.30 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95 -
PROX Valve Shims - 5 pack 29.748235
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance, timing precision, and overall performance—making regular shim replacement critical for serious racers and high-revving builds. PROX Valve Shims deliver OEM-equivalent precision at a fraction...09260893- SKU:
- 09260893
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 2.35 MM
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valve Shims - 5 pack 29.748240
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance and, consequently, your ability to maintain precise tuning. PROX Valve Shims deliver the precision fit and durability you need to keep your valvetrain operating at peak efficiency without the...09260894- SKU:
- 09260894
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- 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
- VALVE SHIM THICKNESS METRIC:
- 2.40 MM
$10.95 -
PROX Valve Shims - 5 pack 29.748245
PROX
$10.95Valve shim wear directly impacts engine performance, combustion efficiency, and cylinder head longevity. These PROX shims deliver OEM-quality precision at a fraction of the cost, making them an essential consumable for any serious engine builder or...09260895- SKU:
- 09260895
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- TYPE:
- VALVE
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 2.45 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- 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 29.748265
PROX
$9.95Valve shim wear directly impacts your engine's performance and longevity. These PROX shims deliver precision tolerances and heat-treated durability that rivals OEM components at a fraction of the cost, making them an essential maintenance item for...09260899- SKU:
- 09260899
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- VALVE SHIM THICKNESS METRIC:
- 2.65 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
$9.95
