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 Impeller Water Pump Cover - Black - YZ125 WPK-31AB
BOYESEN
$219.95Stock water pumps can't keep pace with the demands of high-RPM racing, leaving your YZ125 vulnerable to thermal stress and performance loss. The BOYESEN Impeller Water Pump Cover delivers measurably higher coolant flow across the entire RPM band, keeping...09401471- SKU:
- 09401471
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- PRODUCT NAME:
- IMPELLER
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- NAUTILUS
- BASE COLOR:
- BLACK
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER
$219.95 -
BOYESEN Ignition Cover - Orange - KTM SC-41CO
BOYESEN
$97.95Stock ignition covers are vulnerable to dirt, water, and premature wear—especially in demanding riding conditions. The Boyesen SC-41CO Factory Ignition Cover is cast from high-grade aluminum to provide reliable protection while maintaining a lightweight...09401447- SKU:
- 09401447
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- COLOR/FINISH:
- ORANGE
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
$97.95 -
BOYESEN Ignition Cover - Gold - KTM/Husqvarna SC-41CM
BOYESEN
$87.95Your engine's internals face constant threats from dust, moisture, and debris—especially in trail and off-road conditions. The BOYESEN Ignition Cover replaces the factory plastic alternative with a precision-cast aluminum design that seals reliably and...09401446- SKU:
- 09401446
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
$87.95 -
BOYESEN Clutch Cover - Orange - KTM CC-44AO
BOYESEN
$105.95A lightweight clutch cover is essential for reducing rotating mass and improving engine responsiveness, especially in competitive racing environments where every gram matters. The BOYESEN CC-44AO delivers factory-grade protection without the weight...09401233- SKU:
- 09401233
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- ORANGE
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$105.95 -
BOYESEN Clutch Cover - Gold - KTM CC-41M
BOYESEN
$95.95A factory-style clutch cover that combines lightweight construction with race-proven durability—essential if you're serious about reducing unsprung weight without sacrificing protection. The individually surfaced design guarantees a leak-free seal right...09401229- SKU:
- 09401229
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$95.95 -
BOYESEN Clutch Cover - Black CC-41B
BOYESEN
$95.95A clutch cover does more than protect—it's a visible statement of your commitment to quality and performance. The BOYESEN CC-41B delivers a lightweight design that reduces rotating mass while maintaining the durability your engine demands, backed by...09401228- SKU:
- 09401228
- Availability:
- Ships Same Business Day
- Weight:
- 0.82 LBS
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- STREET
- TYPE:
- CLUTCH
$95.95 -
BOYESEN HY-FLO Water Pump Elbow WPE-18B
BOYESEN
$29.95Cavitation and heat buildup in your cooling system directly reduce engine reliability and performance—especially under sustained high-rpm racing conditions. The BOYESEN HY-FLO Water Pump Elbow eliminates the angled passages where these problems...09401100- SKU:
- 09401100
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- TYPE:
- WATER PUMP
- BASE COLOR:
- BLACK
- PRODUCT NAME:
- ELBOW
- MODEL:
- HY-FLO
$29.95 -
BOYESEN Impeller/Waterpump Cover WPK-07AM
BOYESEN
$194.95Stock water pump covers restrict coolant flow, forcing your engine to work harder to maintain optimal operating temperature. The BOYESEN Impeller/Waterpump Cover WPK-07AM replaces that restriction with a high-flow design that increases circulation across...09400975- SKU:
- 09400975
- Availability:
- Ships Same Business Day
- Weight:
- 0.36 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- BASE FINISH:
- POWDER-COATED
- UNITS:
- KIT
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
$194.95 -
BOYESEN Clutch Cover - CRF250R CC-07AM
BOYESEN
$117.95If you're running a CRF250R in competition or pushing hard on the track, your clutch cover takes a beating from heat, debris, and vibration. The BOYESEN Clutch Cover CC-07AM replaces that worn or damaged stock cover with a lightweight, purpose-built...09400969- SKU:
- 09400969
- Availability:
- Ships Same Business Day
- Weight:
- 0.81 LBS
- COLOR/FINISH:
- MAGNESIUM
- RIDING STYLE:
- OFF-ROAD
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- UNITS:
- EACH
- PRODUCT NAME:
- COVER
$117.95 -
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
$229.95 -
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 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 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
$87.95 -
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 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 - 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
$194.95 -
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 - Gold - CRF250X CC-07XM
BOYESEN
$95.95A quality clutch cover protects one of your bike's most critical components while contributing to the overall aesthetic of your build. The BOYESEN Gold Clutch Cover combines factory-level durability with a refined look that justifies its place on any...09400565- SKU:
- 09400565
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$95.95 -
BOYESEN Clutch Cover - Black - CRF250X CC-07XB
BOYESEN
$95.95A factory clutch cover replacement needs to balance lightweight construction with durability—and the BOYESEN CC-07XB delivers both. The precision-surfaced design eliminates leaks while the powder-coated finish withstands harsh racing conditions and...09400564- SKU:
- 09400564
- Availability:
- Ships Same Business Day
- Weight:
- 0.64 LBS
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$95.95
