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 WPK32AM
BOYESEN
$194.95Engine cooling efficiency directly impacts both performance and longevity, especially under sustained load or competition conditions. The BOYESEN WPK32AM water pump cover and impeller upgrade increases coolant flow across all RPM ranges, maintaining...09400402- SKU:
- 09400402
- Availability:
- Ships Same Business Day
- Weight:
- 0.31 LBS
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
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
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
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
$194.95Qty in Cart: 0Quantity:Price:$194.95Subtotal: -
BOYESEN Impeller/Waterpump Cover WPK-06B
BOYESEN
$194.95Engine cooling efficiency directly impacts performance and longevity—especially under sustained high-RPM operation. The BOYESEN WPK-06B addresses this with a hydrodynamic impeller design that increases coolant flow across all RPM ranges, keeping your...09400397- SKU:
- 09400397
- Availability:
- Ships Same Business Day
- Weight:
- 0.32 LBS
- BASE COLOR:
- BLACK
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- COLOR/FINISH:
- BLACK
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
$194.95 -
BOYESEN Clutch Cover - Gold - YZ125 CC-33M
BOYESEN
$95.95A lightweight clutch cover is essential for reducing unsprung weight and improving overall bike handling, especially in competitive YZ125 applications where every fraction of a pound matters. The Boyesen CC-33M delivers factory-grade protection without...09400396- SKU:
- 09400396
- Availability:
- Ships Same Business Day
- Weight:
- 0.68 LBS
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$95.95 -
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 - Black - YZ125 CC-31B
BOYESEN
$198.95A clutch cover does more than protect—it's a visible statement of your commitment to race-ready precision. The Boyesen CC-31B combines lightweight construction with a factory-engineered fit that eliminates leaks and reduces rotational mass where it...09400392- SKU:
- 09400392
- Availability:
- Ships Same Business Day
- Weight:
- 0.86 LBS
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- COLOR/FINISH:
- POWDER-COATED
$198.95Qty in Cart: 0Quantity:Price:$198.95Subtotal: -
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 - Black - YZ/WR250F CC-37B
BOYESEN
$95.95A lightweight clutch cover cuts unsprung weight and improves handling dynamics without compromising protection—critical for riders pushing lap times. Individually surfaced construction eliminates fitment guesswork and leak issues that plague aftermarket...09400234- SKU:
- 09400234
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- COLOR/FINISH:
- BLACK
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Clutch Cover - Gold - RM250 CC-22M
BOYESEN
$95.95A quality clutch cover protects one of your engine's most critical components while establishing the visual foundation of your build. The BOYESEN Clutch Cover delivers lightweight construction without sacrificing the durability needed for sustained...09400232- SKU:
- 09400232
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- TYPE:
- CLUTCH
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
$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 Clutch Cover - Gold - CR450F CC-06M
BOYESEN
$95.95A clutch cover does more than protect—it's a visual statement of your commitment to quality and performance. The BOYESEN Gold Clutch Cover combines race-proven durability with a lightweight design that reduces unsprung mass, while its precision-surfaced...09400226- SKU:
- 09400226
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$95.95 -
BOYESEN Clutch Cover - Black - CR450F CC-06B
BOYESEN
$95.95A clutch cover isn't just cosmetic—it's your first line of defense against debris, heat, and premature wear. The BOYESEN CC-06B delivers the lightweight construction you need for race applications while maintaining a factory-tight seal that won't fail...09400225- SKU:
- 09400225
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- COLOR/FINISH:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Clutch Cover - Gold - CR250 CC-02AM
BOYESEN
$95.95If you're running a CR250 at the track or trail, your clutch cover takes a beating. The BOYESEN Lightweight Clutch Cover combines factory-level protection with measurable weight savings, helping you optimize your power-to-weight ratio without...09400223- SKU:
- 09400223
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- COLOR/FINISH:
- MAGNESIUM
- 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 - 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
