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 29.748270
PROX
$9.95Valve shims are critical wear items that directly affect your engine's valve clearance and overall performance. Over time, factory shims wear down, causing improper valve timing and reduced power output—PROX Valve Shims eliminate guesswork with...09260900- SKU:
- 09260900
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.70 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
$9.95 -
PROX Valve Shims - 5 pack 29.748275
PROX
$10.95Valve shim wear is one of the most overlooked maintenance items in high-performance engines—but ignoring it costs you precision and reliability. These PROX shims deliver OEM-equivalent performance at a fraction of the replacement cost, making them an...09260901- SKU:
- 09260901
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.75 MM
- 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
- RIDING STYLE:
- STREET
$10.95 -
PROX Valve Shims - 5 pack 29.748280
PROX
$10.95Valve shim wear is one of the most common causes of performance loss and costly engine rebuilds. PROX Valve Shims deliver precision-engineered replacements that restore proper valve clearance without the expense of OEM parts, keeping your engine running...09260902- SKU:
- 09260902
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.80 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
$10.95 -
PROX Valve Shims - 5 pack 29.748285
PROX
$10.95Valve shim wear is one of the most common causes of valvetrain noise and performance loss in high-revving engines. These PROX shims deliver precision-matched sizing and heat-treated durability to maintain exact valve clearances without the premium cost...09260903- SKU:
- 09260903
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- STREET
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 2.85 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valve Shims - 5 pack 29.748290
PROX
$10.95Valve shims wear down over time, causing timing drift and performance loss—replacement is inevitable for any serious builder or racer. PROX Valve Shims deliver precision-machined durability at a fraction of OEM costs, letting you maintain tight...09260904- SKU:
- 09260904
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 2.90 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- 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 29.748295
PROX
$10.95Valve shims are a wear item that directly impacts valve clearance and engine performance—replacing worn OEM shims is essential for maintaining proper valve train geometry and preventing costly damage. PROX Valve Shims deliver precision-machined...09260905- SKU:
- 09260905
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.95 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 29.748320
PROX
$9.95Valve shim wear is one of the most common causes of valve train noise and performance loss in high-revving engines. These PROX shims deliver precision fitment and heat-treated durability at a fraction of OEM replacement costs, making them the smart...09260910- SKU:
- 09260910
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- VALVE SHIM THICKNESS METRIC:
- 3.20 MM
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
$9.95 -
PROX Valve Shim Kit 29.VSA890
PROX
$77.95Valve shim wear is one of the most common causes of performance loss and engine noise in high-revving applications. The PROX Valve Shim Kit 29.VSA890 delivers precision-engineered replacements that restore your engine's valvetrain accuracy without the...09260917- SKU:
- 09260917
- Availability:
- Ships Same Business Day
- Weight:
- 0.54 LBS
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- KIT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 1.72 MM - 2.60 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- STREET
$77.95 -
PROX Valveshim - 5 pack 29.890204
PROX
$10.95Valve shim wear directly impacts valve clearance, which affects combustion efficiency, valve timing, and engine longevity. The PROX Valveshim 5-pack (29.890204) delivers precision-machined replacements at a fraction of OEM costs, eliminating the need for...09260926- SKU:
- 09260926
- 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:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 2.04 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
$10.95 -
PROX Valveshim - 5 pack 29.890208
PROX
$10.95Valve shims are critical to maintaining proper valve clearance and preventing catastrophic engine damage from improper valvetrain geometry. These PROX shims deliver precision-machined consistency and heat-treated durability at a fraction of OEM...09260927- SKU:
- 09260927
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- VALVE SHIM THICKNESS METRIC:
- 2.08 MM
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
$10.95 -
PROX Valveshim - 5 pack 29.890212
PROX
$10.95Valve shims are critical wear items that directly impact valve clearance, engine timing, and overall performance—neglecting them leads to improper valve operation and potential damage. PROX Valveshims deliver precision-machined replacements at a fraction...09260928- SKU:
- 09260928
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- STREET
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 2.12 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valveshim - 5 pack 29.890216
PROX
$10.95Valve shim wear directly impacts your engine's valve clearance, compression, and overall performance—left unchecked, it leads to costly damage and downtime. PROX Valveshims deliver precision-engineered replacements at a fraction of OEM costs, with...09260929- SKU:
- 09260929
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.16 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
$10.95 -
PROX Valveshim - 5 pack 29.890220
PROX
$10.95Valve shim wear is inevitable in high-performance engines, but replacing them doesn't require the expense and downtime of OEM components. The PROX Valveshim 5-pack delivers precision-engineered replacements at a fraction of the cost, with heat-treated...09260930- SKU:
- 09260930
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.20 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
$10.95 -
PROX Valveshim - 5 pack 29.890224
PROX
$10.95Valve shims wear down with every engine cycle, and worn shims throw off valve clearance—leading to reduced power, increased noise, and potential valve damage. The PROX Valveshim 5-pack gives you precision replacements that maintain exact factory specs...09260931- SKU:
- 09260931
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.24 MM
- OUTSIDE DIAMETER METRIC:
- 8.90 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 Valveshim - 5 pack 29.890228
PROX
$10.95Valve shims are critical to maintaining proper valve clearance and ensuring consistent engine performance across heat cycles. The PROX 5-pack gives you multiple precision replacements on hand, eliminating costly downtime waiting for OEM parts while...09260932- SKU:
- 09260932
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.28 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
$10.95 -
PROX Valveshim - 5 pack 29.890244
PROX
$9.95Valve shims are critical wear items in high-revving engines, and OEM replacements can drain your budget fast. The PROX Valveshim 5-pack delivers precision-machined replacements at a fraction of OEM cost, with proprietary heat-treatment that matches or...09260936- SKU:
- 09260936
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 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:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.44 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
$9.95 -
PROX Valveshim - 5 pack 29.890256
PROX
$9.95Valve shim wear directly impacts valve clearance, which affects combustion timing, power delivery, and engine longevity. PROX Valveshims give you precision replacements without the OEM price tag, letting you maintain tight tolerances on a practical...09260939- SKU:
- 09260939
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- WATERCRAFT
- 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
- VALVE SHIM THICKNESS METRIC:
- 2.56 MM
- RIDING STYLE:
- STREET
$9.95 -
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
