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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BOYESEN Ignition Cover - Gold - YZ250 SC-32AM
BOYESEN
$87.95The stock ignition cover on your YZ250 isn't just cosmetic—it's your engine's first line of defense against dirt, water, and debris that can compromise internal components. A quality replacement...09400220- SKU:
- 09400220
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$87.95 -
BOYESEN Ignition Cover - Gold - RM250 SC-23M
BOYESEN
$87.95A quality ignition cover is essential protection against the elements—dirt, water, and debris can compromise engine reliability if left exposed. The BOYESEN Factory Ignition Cover delivers OEM-level...09400218- SKU:
- 09400218
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- PRODUCT NAME:
- COVER
- MATERIAL:
- ALUMINUM
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Ignition Cover - Gold - RM125 SC-21CM
BOYESEN
$87.95The stock ignition cover on your RM125 takes a beating—dirt, water, and constant vibration compromise engine integrity and longevity. A quality replacement like the Boyesen Factory Cover seals...09400217- SKU:
- 09400217
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Ignition Cover - Gold - KX250 SC-12M
BOYESEN
$87.95Keep your KX250's ignition system protected from the elements with a cover that matches factory standards while outlasting the stock alternative. Boyesen's cast aluminum construction provides the...09400215- SKU:
- 09400215
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$87.95 -
BOYESEN Ignition Cover - Gold - KX125 SC-11AM
BOYESEN
$87.95A quality ignition cover isn't just cosmetic—it's essential protection for your engine's most vulnerable components. The BOYESEN Factory Ignition Cover seals out dirt and water that can compromise...09400214- SKU:
- 09400214
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Ignition Cover - Gold - CR500 SC-03M
BOYESEN
$87.95A quality ignition cover is a small detail that separates a well-maintained engine from one heading toward premature wear. The Boyesen Factory Ignition Cover protects your CR500's internal components...09400212- SKU:
- 09400212
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Ignition Cover - Gold - CR250 SC02AM
BOYESEN
$87.95A properly sealed ignition cover is critical for engine longevity—it keeps dirt, moisture, and contaminants away from ignition components that can't tolerate exposure. The Boyesen Factory Cover...09400211- SKU:
- 09400211
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Replacement Gasket - KTM CCG-41
BOYESEN
$7.00Factory clutch covers are prone to warping under sustained racing conditions, compromising your seal integrity and risking fluid leakage at critical moments. The BOYESEN CCG-41 replaces OEM gaskets...09343124- SKU:
- 09343124
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- MATERIAL:
- NITRILE RUBBER
- UNITS:
- EACH
- PRODUCT NAME:
- GASKET
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
$7.00Qty in Cart: 0Quantity:Price:$7.00Subtotal: -
BOYESEN Replacement Gasket CCG-42
BOYESEN
$7.00A clutch cover gasket is critical to preventing oil seepage and maintaining consistent engine temperatures during high-demand racing conditions. The BOYESEN CCG-42 eliminates the leak-prone factory...09341291- SKU:
- 09341291
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
- MATERIAL:
- NITRILE RUBBER
- PRODUCT NAME:
- GASKET
- UNITS:
- EACH
$7.00 -
BOYESEN Replacement Gasket SCG-42
BOYESEN
$5.95Engine covers take a beating from dirt, moisture, and temperature swings—stock gaskets degrade quickly and compromise your seal integrity. The BOYESEN SCG-42 replacement gasket delivers a reliable,...09341290- SKU:
- 09341290
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION COVER GASKET
- MATERIAL:
- NITRILE RUBBER
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- GASKET
- UNITS:
- EACH
$5.95Qty in Cart: 0Quantity:Price:$5.95Subtotal: -
BOYESEN Ignition Cover Gasket SCG-41
BOYESEN
$5.95A degraded ignition cover gasket compromises engine sealing, allowing moisture and contaminants to infiltrate critical internal components. The Boyesen SCG-41 delivers a factory-quality seal with...09341285- SKU:
- 09341285
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION COVER GASKET
- MATERIAL:
- NITRILE RUBBER
- PRODUCT NAME:
- GASKET
- UNITS:
- EACH
$5.95 -
BOYESEN Replacement Gasket - KTM CCG-46
BOYESEN
$7.00A worn or damaged clutch cover gasket compromises your engine's seal integrity, leading to oil leaks and potential performance loss during high-RPM running. The BOYESEN CCG-46 replacement gasket...09341283- SKU:
- 09341283
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- MATERIAL:
- NITRILE RUBBER
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
- UNITS:
- EACH
- PRODUCT NAME:
- GASKET
$7.00 -
BOYESEN Replacement Gasket CCG-27
BOYESEN
$7.00Factory clutch cover gaskets wear out and degrade under heat and pressure, leading to oil seepage and potential engine damage. The BOYESEN CCG-27 replacement gasket eliminates leaks with a...09341272- SKU:
- 09341272
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
- PRODUCT NAME:
- GASKET
- MATERIAL:
- NITRILE RUBBER
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
- UNITS:
- EACH
$7.00Qty in Cart: 0Quantity:Price:$7.00Subtotal: -
BOYESEN Clutch Cover Gasket CCG-06X
BOYESEN
$7.00A compromised clutch cover gasket means oil seepage, potential drivetrain contamination, and unreliable performance when you need it most. The BOYESEN CCG-06X eliminates these risks with a...09340959- SKU:
- 09340959
- Availability:
- Ships Same Business Day
- Weight:
- 0.03 LBS
- RIDING STYLE:
- STREET
- TYPE:
- CLUTCH COVER
- MATERIAL:
- NITRILE RUBBER
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- GASKET
- UNITS:
- EACH
$7.00 -
BOYESEN Impeller/Waterpump Cover - Magnesium WPK-18AM
BOYESEN
$194.95Engine temperature stability is critical to reliability and longevity, especially under sustained load or racing conditions. The Boyesen WPK-18AM upgrades your cooling system with a high-flow...09320163- SKU:
- 09320163
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- MATERIAL:
- ALUMINUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- MAGNESIUM
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- UNITS:
- KIT
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
BOYESEN Impeller/Waterpump Cover - Black WPK-18AB
BOYESEN
$194.95Engine coolant flow directly impacts operating temperature stability and component longevity. The BOYESEN WPK-18AB water pump cover and impeller assembly uses a patented nautilus-style impeller...09320162- SKU:
- 09320162
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- BASE COLOR:
- BLACK
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- TYPE:
- WATER PUMP
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
BOYESEN Impeller/Waterpump Cover - Orange WPK-45AO
BOYESEN
$199.95Engine temperature stability is critical to maintaining reliability and longevity, especially under sustained racing or high-load conditions. The Boyesen WPK-45AO addresses this directly by...09320160- SKU:
- 09320160
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- BASE COLOR:
- ORANGE
- UNITS:
- KIT
- BASE FINISH:
- POWDER-COATED
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- ORANGE
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- TYPE:
- WATER PUMP
$199.95 -
BOYESEN Impeller/Waterpump Cover - Magnesium WPK-45AM
BOYESEN
$194.95Engine heat is the silent killer of performance and reliability—especially under sustained racing conditions or aggressive driving. The Boyesen WPK-45AM water pump cover and impeller assembly solves...09320159- SKU:
- 09320159
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- COLOR/FINISH:
- MAGNESIUM
- UNITS:
- KIT
- BASE FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- TYPE:
- WATER PUMP
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
BOYESEN Impeller/Waterpump Cover - Black WPK-45AB
BOYESEN
$194.95Engine cooling efficiency directly impacts performance, reliability, and longevity—especially under sustained high-RPM operation. The BOYESEN Impeller/Waterpump Cover addresses cooling system...09320158- SKU:
- 09320158
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- MATERIAL:
- ALUMINUM
- RIDING STYLE:
- STREET
- BASE COLOR:
- BLACK
- TYPE:
- WATER PUMP
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- UNITS:
- KIT
$194.95 -
BOYESEN Impeller/Waterpump Cover - Magnesium WPK-44AM
BOYESEN
$194.95Engine cooling efficiency directly impacts performance, reliability, and longevity—especially under sustained high-RPM operation. The BOYESEN WPK-44AM water pump cover and impeller combo increases...09320155- SKU:
- 09320155
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- MAGNESIUM
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
$194.95
