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 Clutch Cover - Gold - Kawasaki/Suzuki CC-17M
BOYESEN
$95.95If you're serious about race performance, your clutch cover needs to match your commitment to lightweight efficiency and reliability. The BOYESEN Clutch Cover eliminates unnecessary weight while delivering the precision fit and durability required in...09400446- SKU:
- 09400446
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$95.95 -
BOYESEN Clutch Cover - Gold - CRF250 CC-07M
BOYESEN
$95.95The BOYESEN Clutch Cover delivers both protection and visual impact, combining lightweight construction with race-ready aesthetics. Its precision-surfaced design ensures a leak-free seal that holds up through demanding track sessions and regular riding...09400443- SKU:
- 09400443
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$95.95 -
BOYESEN Impeller/Waterpump Cover - Magnesium WPK-38M
BOYESEN
$194.95Engine cooling efficiency directly impacts performance and longevity. The BOYESEN WPK-38M waterpump cover and impeller combo uses a patented nautilus-style impeller design to increase coolant flow across all RPM ranges, keeping your engine running at a...09400414- SKU:
- 09400414
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- BASE FINISH:
- POWDER-COATED
- TYPE:
- WATER PUMP
- UNITS:
- KIT
$194.95 -
BOYESEN Impeller/Waterpump Cover - Black WPK-07B
BOYESEN
$194.95Engine coolant flow directly impacts operating temperature stability and component longevity—especially under sustained high-RPM operation. The Boyesen WPK-07B uses a patented nautilus-style impeller geometry to increase coolant displacement across the...09400406- SKU:
- 09400406
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- BASE COLOR:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- MODEL:
- SUPERCOOLER
- TYPE:
- WATER PUMP
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- MATERIAL:
- ALUMINUM
$194.95 -
BOYESEN Impeller/Waterpump Cover WPK37B
BOYESEN
$194.95Engine temperature stability is critical to reliability and longevity, especially under sustained load or racing conditions. The Boyesen WPK37B water pump cover and impeller upgrade increases coolant flow across all RPM ranges, allowing your engine to...09400403- SKU:
- 09400403
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- BASE COLOR:
- BLACK
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$194.95 -
BOYESEN Impeller/Waterpump Cover WPK32AB
BOYESEN
$194.95Engine thermal management directly impacts reliability, performance consistency, and longevity—especially under sustained racing conditions or high-load operation. The BOYESEN Impeller/Waterpump Cover WPK32AB uses a patented nautilus-style impeller...09400401- SKU:
- 09400401
- Availability:
- Ships Same Business Day
- Weight:
- 0.31 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- TYPE:
- WATER PUMP
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- BASE COLOR:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$194.95 -
BOYESEN Impeller/Waterpump Cover WPK-31B
BOYESEN
$194.95Engine coolant flow directly impacts operating temperature stability and longevity—particularly under sustained high-RPM conditions where thermal management becomes critical. The BOYESEN WPK-31B replaces the stock water pump cover and impeller with a...09400399- SKU:
- 09400399
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- BASE COLOR:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
$194.95 -
BOYESEN Impeller/Waterpump Cover WPK-06M
BOYESEN
$194.95Engine cooling efficiency directly impacts performance and longevity—inadequate coolant flow forces your engine to operate at inconsistent temperatures, compromising both power output and component lifespan. The BOYESEN WPK-06M water pump cover and...09400398- SKU:
- 09400398
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
$194.95 -
BOYESEN Clutch Cover - Black - YZ125 CC-33B
BOYESEN
$95.95A clutch cover isn't just protection—it's a statement of maintenance standards and ride reliability. The BOYESEN CC-33B delivers factory-grade durability with a lightweight design that won't add rotational mass to your YZ125, while the precision-surfaced...09400395- SKU:
- 09400395
- Availability:
- Ships Same Business Day
- Weight:
- 1.19 LBS
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$95.95 -
BOYESEN Clutch Cover - Gold - YZ125 CC-31M
BOYESEN
$198.95A lightweight clutch cover isn't just about aesthetics—it reduces unsprung weight and heat retention while maintaining the durability your YZ125 demands in competition. The Boyesen CC-31M delivers factory-grade protection with a precision-surfaced design...09400393- SKU:
- 09400393
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- COLOR/FINISH:
- MAGNESIUM
- TYPE:
- CLUTCH
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
$198.95 -
BOYESEN Clutch Cover - Gold - KX250 CC-12CM
BOYESEN
$95.95A lightweight clutch cover reduces unsprung weight and rotational mass—critical factors in KX250 performance where every fraction matters. The BOYESEN Gold cover combines factory-grade durability with a precision-surfaced design that eliminates leaks and...09400390- SKU:
- 09400390
- Availability:
- Ships Same Business Day
- Weight:
- 1.03 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$95.95 -
BOYESEN Clutch Cover - Gold - YZ/WR250F CC-37M
BOYESEN
$95.95A lightweight clutch cover reduces unsprung weight and rotational mass, directly improving throttle response and handling characteristics on your YZ/WR250F. The factory-spec design delivers OEM protection without the factory weight penalty, giving you...09400235- SKU:
- 09400235
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- UNITS:
- EACH
- PRODUCT NAME:
- COVER
- COLOR/FINISH:
- MAGNESIUM
$95.95 -
BOYESEN Clutch Cover - Gold - RM125 CC-21AM
BOYESEN
$95.95A quality clutch cover is essential for protecting your engine's internal components while maintaining a clean, professional appearance in the paddock. The BOYESEN Clutch Cover delivers lightweight construction and factory-grade precision fit,...09400231- SKU:
- 09400231
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- PRODUCT NAME:
- COVER
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$95.95 -
BOYESEN Clutch Cover - Gold - KX250 CC-12M
BOYESEN
$95.95A factory clutch cover is critical protection for your KX250's clutch basket and internal components—one crash or debris strike can mean a complete engine teardown. The BOYESEN Gold Clutch Cover combines lightweight construction with precision...09400229- SKU:
- 09400229
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- COLOR/FINISH:
- MAGNESIUM
$95.95 -
BOYESEN Clutch Cover - Gold - KX125 CC-11AM
BOYESEN
$95.95A clutch cover does more than protect—it's a visible statement of your commitment to precision engineering and race-ready performance. The BOYESEN Gold Clutch Cover combines lightweight construction with a factory-finish aesthetic, giving you authentic...09400228- SKU:
- 09400228
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- UNITS:
- EACH
$95.95 -
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 cover like the BOYESEN Factory model seals properly and...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 - 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 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 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
