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 Shims - 5 pack 29.748310
PROX
$9.95Valve shim wear directly impacts engine performance and reliability—precision valve timing depends on exact shim clearances, and worn units compromise both. PROX Valve Shims deliver OEM-quality fitment at a fraction of OEM pricing, making routine...09260908- SKU:
- 09260908
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 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
- VALVE SHIM THICKNESS METRIC:
- 3.10 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 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 29.890172
PROX
$9.95Valve shims are critical wear items that directly affect valve clearance and engine timing precision—neglect them and you risk catastrophic valvetrain failure. PROX Valveshims deliver OEM-equivalent performance at a fraction of the cost, giving you a...09260918- SKU:
- 09260918
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 1.72 MM
- RIDING STYLE:
- STREET
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 5 pack 29.890188
PROX
$9.95Valve shims wear down over time, throwing off your engine's valve clearances and compromising performance and reliability. PROX Valveshims give you a cost-effective replacement option without the premium price tag of OEM components—critical for racers...09260922- SKU:
- 09260922
- 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:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 1.88 MM
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 5 pack 29.890192
PROX
$9.95Valve shims are wear components that demand precision and durability—especially under high RPM conditions where tolerance stack-up can quickly degrade performance. The PROX Valveshim 5-pack delivers OEM-equivalent quality at a fraction of the cost, with...09260923- SKU:
- 09260923
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 1.92 MM
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 5 pack 29.890196
PROX
$9.95Valve shims are critical wear components that directly impact valve clearance, timing accuracy, and engine longevity. PROX Valveshims deliver OEM-equivalent precision at a fraction of the cost, making them an economical choice for both race engines and...09260924- SKU:
- 09260924
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 1.96 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 5 pack 29.890200
PROX
$9.95Valve shims are critical to maintaining proper valve clearance and preventing costly engine damage from over-tightening or excessive wear. The PROX Valveshim 5-pack offers precision-machined replacements that restore OEM tolerances at a fraction of the...09260925- SKU:
- 09260925
- 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
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 2.00 MM
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
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 29.890232
PROX
$9.95Valve shims are critical wear components that demand precision and durability—especially in high-RPM applications where tolerance stack-up directly impacts engine performance and reliability. The PROX Valveshim 5-pack offers OEM-equivalent quality at a...09260933- SKU:
- 09260933
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.32 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- 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
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 5 pack 29.890236
PROX
$9.95Valve shim wear is one of the most common maintenance issues in high-performance engines, directly affecting valve clearance and engine efficiency. The PROX Valveshim 5-pack offers a cost-effective replacement solution that meets OEM specifications...09260934- SKU:
- 09260934
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 2.36 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
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valveshim - 5 pack 29.890240
PROX
$9.95Valve shims are critical wear items that directly impact your engine's valve clearance and overall performance. When OEM shims wear or require replacement, PROX delivers precision-machined alternatives at a fraction of OEM costs. This 5-pack ensures you...09260935- SKU:
- 09260935
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- VALVE SHIM THICKNESS METRIC:
- 2.40 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
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
