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
-
BOYESEN Impeller/Waterpump Cover - Magnesium WPK-26AM
BOYESEN
$229.95Engine temperatures climb under sustained load, threatening reliability and power output—especially in high-performance applications where stock cooling systems fall short. The BOYESEN WPK-26AM water pump cover and impeller upgrade increases coolant flow...09400862- SKU:
- 09400862
- Availability:
- Ships Same Business Day
- Weight:
- 0.64 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- TYPE:
- WATER PUMP
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$229.95Qty in Cart: 0Quantity:Price:$229.95Subtotal: -
BOYESEN Impeller/Waterpump Cover - Black WPK-26AB
BOYESEN
$229.95Engine cooling efficiency directly impacts performance, reliability, and longevity—especially under sustained load or competitive conditions. The BOYESEN Impeller/Waterpump Cover upgrades your cooling system with a high-flow design that maintains lower,...09400861- SKU:
- 09400861
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- COLOR/FINISH:
- BLACK
- MATERIAL:
- ALUMINUM
- BASE FINISH:
- POWDER-COATED
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- TYPE:
- WATER PUMP
- BASE COLOR:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$229.95Qty in Cart: 0Quantity:Price:$229.95Subtotal: -
BOYESEN Impeller/Waterpump Cover WPK-20M
BOYESEN
$219.95Engine cooling efficiency directly impacts performance, longevity, and reliability—especially under sustained high-RPM operation. The BOYESEN Impeller/Waterpump Cover WPK-20M delivers measurably higher coolant flow across the entire RPM band, maintaining...09400734- SKU:
- 09400734
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- TYPE:
- WATER PUMP
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
$219.95 -
BOYESEN Impeller/Waterpump Cover WPK-20B
BOYESEN
$219.95Engine thermal management directly impacts reliability, longevity, and consistent performance across all RPM ranges. The BOYESEN WPK-20B addresses cooling system limitations with a high-flow water pump design that maintains optimal operating temperatures...09400733- SKU:
- 09400733
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- BASE COLOR:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- TYPE:
- WATER PUMP
- UNITS:
- KIT
$219.95 -
BOYESEN Clutch Cover - Gold - KTM CC-42M
BOYESEN
$95.95A lightweight clutch cover is essential for reducing unsprung mass and improving your KTM's power-to-weight ratio—every gram counts in competitive racing. The Boyesen CC-42M combines race-proven design with meticulous manufacturing to deliver reliable...09400706- SKU:
- 09400706
- Availability:
- Ships Same Business Day
- Weight:
- 0.95 LBS
- COLOR/FINISH:
- MAGNESIUM
- RIDING STYLE:
- OFF-ROAD
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER
$95.95 -
BOYESEN Clutch Cover - Black - KTM CC-42B
BOYESEN
$95.95Factory clutch covers are engineered for durability in demanding race environments, and the BOYESEN CC-42B delivers lightweight protection without compromising reliability. If you're running hard on track or trail, you need a cover that seals tight and...09400705- SKU:
- 09400705
- Availability:
- Ships Same Business Day
- Weight:
- 0.96 LBS
- COLOR/FINISH:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- COVER
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Ignition Cover - Black SC-42B
BOYESEN
$87.95Engine covers aren't just cosmetic—they're critical protection against dirt, water, and debris that can compromise internal engine components. The Boyesen SC-42B Factory Ignition Cover combines OEM-grade engineering with superior materials and...09400702- SKU:
- 09400702
- Availability:
- Ships Same Business Day
- Weight:
- 0.66 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- STREET
- MATERIAL:
- ALUMINUM
$87.95 -
BOYESEN Ignition Cover - Black SC-41B
BOYESEN
$87.95Engine covers aren't just cosmetic—they're essential protection against the elements. The BOYESEN Ignition Cover keeps dirt, water, and debris out of your engine bay while maintaining a factory-correct appearance. Built from high-grade aluminum and...09400699- SKU:
- 09400699
- Availability:
- Ships Same Business Day
- Weight:
- 0.71 LBS
- COLOR/FINISH:
- BLACK
- MATERIAL:
- ALUMINUM
- RIDING STYLE:
- STREET
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Ignition Cover - KTM 85/105 SC-46M
BOYESEN
$87.95A factory-quality ignition cover protects your engine's most vulnerable internal components from the elements—dirt, water, and debris that accelerate wear and corrosion. The BOYESEN SC-46M delivers OEM-level sealing and durability while improving the...09400697- SKU:
- 09400697
- Availability:
- Ships Same Business Day
- Weight:
- 0.58 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
$87.95 -
BOYESEN Ignition Cover - KTM 85/105 SC-46B
BOYESEN
$87.95The factory ignition cover protects your KTM's engine internals from the elements while delivering the professional appearance and durability of OEM components. Boyesen's aluminum construction withstands the demands of competitive riding and trail use...09400696- SKU:
- 09400696
- Availability:
- Ships Same Business Day
- Weight:
- 0.58 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Clutch Cover - KTM 85/105 CC-46M
BOYESEN
$95.95OEM clutch covers add unnecessary weight and restrict airflow when you need it most—the BOYESEN CC-46M replaces the stock cover with a precision-engineered alternative that cuts mass while improving cooling and aesthetics. Individually surfaced for a...09400694- SKU:
- 09400694
- Availability:
- Ships Same Business Day
- Weight:
- 0.58 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- PRODUCT NAME:
- COVER
$95.95 -
BOYESEN Clutch Cover - KTM 85/105 CC-46B
BOYESEN
$95.95A factory-spec clutch cover that combines lightweight construction with proven durability—essential for KTM 85/105 riders who demand reliability without compromising performance. The individually surfaced design eliminates common leak points, while the...09400693- SKU:
- 09400693
- Availability:
- Ships Same Business Day
- Weight:
- 0.58 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
$95.95 -
BOYESEN Supercooler Waterpump WPK-27B
BOYESEN
$229.95Engine temperatures directly impact performance, reliability, and longevity—especially under sustained racing conditions or high-load operations. The BOYESEN Supercooler WPK-27B addresses this critical need with a high-flow water pump design that...09400690- SKU:
- 09400690
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- BASE COLOR:
- BLACK
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- TYPE:
- WATER PUMP
$229.95 -
BOYESEN Clutch Cover - Gold CC-27AM
BOYESEN
$95.95If you're serious about reducing rotating mass and shaving weight off your engine, the BOYESEN Clutch Cover delivers the lightweight performance upgrade your bike needs without sacrificing durability. Factory-engineered precision ensures a perfect seal...09400683- SKU:
- 09400683
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- TYPE:
- CLUTCH
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- MAGNESIUM
$95.95 -
BOYESEN Clutch Cover - Black CC-27AB
BOYESEN
$95.95A clutch cover does more than protect your engine—it's a visual statement of your commitment to performance and precision. The BOYESEN Clutch Cover CC-27AB delivers race-grade protection with a factory-lightweight design that reduces rotating mass...09400682- SKU:
- 09400682
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- TYPE:
- CLUTCH
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
$95.95 -
BOYESEN Impeller/Waterpump Cover - Magnesium WPK-09M
BOYESEN
$206.65Engine temperatures spike under sustained load, reducing efficiency and accelerating wear on critical components. The BOYESEN WPK-09M water pump cover and impeller assembly increases coolant flow across all RPM ranges, keeping your engine operating at...09400680- SKU:
- 09400680
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 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
$206.65Qty in Cart: 0Quantity:Price:$206.65Subtotal: -
BOYESEN Impeller/Waterpump Cover - Black WPK-09B
BOYESEN
$194.95Engine temperature management directly impacts performance, reliability, and longevity—especially under sustained load or competition conditions. The Boyesen WPK-09B upgrades your cooling system with a high-flow impeller design that increases coolant...09400679- SKU:
- 09400679
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 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
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
BOYESEN Clutch Cover - Gold - CRF450 CC-06XM
BOYESEN
$95.95Factory-spec clutch covers protect your engine's most critical component while shaving unnecessary weight—essential for racers and serious builders who demand precision fit and zero leakage. BOYESEN's individually surfaced design ensures a perfect seal...09400615- SKU:
- 09400615
- Availability:
- Ships Same Business Day
- Weight:
- 0.89 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 - Black - CRF450 CC-06XB
BOYESEN
$95.95A clutch cover does more than protect—it defines your bike's visual identity while delivering the durability your engine demands. The BOYESEN Clutch Cover combines lightweight construction with precision engineering to reduce rotating mass without...09400614- SKU:
- 09400614
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- PRODUCT NAME:
- COVER
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- BLACK
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Impeller/Waterpump Cover - Black WPK-18B
BOYESEN
$194.95Engine cooling efficiency directly impacts both performance and longevity, especially under sustained high-RPM operation. The Boyesen WPK-18B water pump cover and impeller assembly increases coolant flow across all RPM ranges, keeping your engine running...09400576- SKU:
- 09400576
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- TYPE:
- WATER PUMP
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BASE COLOR:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$194.95
