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 29.748190
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
$10.95Qty in Cart: 0Quantity:Price:$10.95Subtotal: -
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 29.748250
PROX
$9.95Valve shim wear directly impacts your engine's valve clearance—and precision matters when you're chasing consistent performance. PROX Valve Shims give you OEM-quality replacements at a fraction of the cost, so you can maintain tight tolerances without...09260896- SKU:
- 09260896
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- VALVE SHIM THICKNESS METRIC:
- 2.50 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 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
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
PROX Valve Shims - 5 pack 29.748260
PROX
$9.95Valve shim wear directly impacts your engine's precision and performance—worn shims lead to improper valve clearance, reduced efficiency, and potential mechanical damage. PROX Valve Shims deliver OEM-quality replacement at a fraction of the cost,...09260898- SKU:
- 09260898
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.60 MM
$9.95Qty in Cart: 0Quantity:Price:$9.95Subtotal: -
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 -
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
