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 - 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 sealing with superior durability, combining lightweight...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 properly to guard critical internal components while...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
$87.95 -
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 durability needed for both track sessions and trail...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 internal engine health, while its cast aluminum...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
$87.95 -
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 from moisture, dirt, and contaminants while delivering...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
$87.95 -
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 outperforms stock units with premium aluminum construction...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
$87.95 -
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 with individually surfaced, asbestos-free construction...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
$7.00 -
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 gasket with a precision-surfaced, asbestos-free design...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, long-lasting seal using premium materials and design...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 materials and construction that outlast OEM gaskets,...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 delivers a factory-grade, leak-free fit with materials...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 precision-surfaced design and asbestos-free construction,...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 precision-surfaced, asbestos-free design that delivers a true...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 impeller and optimized pump cover that increases coolant...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 design to increase coolant circulation across all RPM...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 increasing coolant flow across the entire RPM range, which means...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 this by increasing coolant flow across all RPM ranges,...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
$194.95 -
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 bottlenecks by increasing coolant flow across the entire RPM...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
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
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 coolant flow across the entire RPM range, maintaining...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 -
BOYESEN Impeller/Waterpump Cover - Black WPK-44AB
BOYESEN
$194.95Engine temperature stability is critical to reliability and longevity, especially under sustained performance driving. The Boyesen WPK-44AB delivers measurable cooling gains by increasing coolant flow across the entire RPM range, keeping your engine...09320154- SKU:
- 09320154
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- UNITS:
- KIT
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- TYPE:
- WATER PUMP
- BASE COLOR:
- BLACK
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- RIDING STYLE:
- OFF-ROAD
$194.95
