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
-
Wossner Piston Kit Honda CRF450R 2005-2008 8608DA
WOSSNER
$214.00High-mileage and competition use demand a piston that can handle sustained heat and load cycles without sacrificing reliability. The Wossner 8608DA delivers the durability and friction reduction your CRF450R needs to perform consistently, whether you're...09104944- SKU:
- 09104944
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE SIZE METRIC:
- 96.00 MM
- PRODUCT NAME:
- PISTON KIT
- BORE - OVERSIZE:
- STANDARD
- COMPRESSION RATIO IMPERIAL:
- 12.0:1
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- PISTON SIZE METRIC:
- 95.96 MM
- MODEL:
- PREMIUM SERIES
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$214.00 -
BOYESEN Impeller Pump YZ250F WPI-37
BOYESEN
$79.95Stock water pumps on the YZ250F can't keep pace with sustained high-RPM racing demands, leading to thermal creep and power loss when you need it most. The BOYESEN WPI-37 Impeller Pump solves this with optimized impeller geometry that increases coolant...WPI37- SKU:
- WPI37
- Availability:
- Ships Same Business Day
- Weight:
- 0.14 LBS
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- IMPELLER
- UNITS:
- EACH
- TYPE:
- WATER PUMP
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
$79.95 -
BOYESEN Impeller Pump YZ/WR WPI-32A
BOYESEN
$79.95Sustained cooling performance is critical during extended racing sessions—thermal cycling and pressure spikes can compromise water flow and allow temperatures to creep into the danger zone. The BOYESEN Impeller Pump WPI-32A counters this with optimized...WPI32A- SKU:
- WPI32A
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- PRODUCT NAME:
- IMPELLER
- RIDING STYLE:
- OFF-ROAD
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- TYPE:
- WATER PUMP
- UNITS:
- EACH
$79.95Qty in Cart: 0Quantity:Price:$79.95Subtotal: -
BOYESEN Clutch Cover - Gold CC-17AM
BOYESEN
$95.95A clutch cover does more than protect—it defines your bike's aesthetic while delivering the durability your engine demands. The BOYESEN Clutch Cover CC-17AM combines lightweight construction with a factory-grade finish, eliminating the risk of leaks that...09401117- SKU:
- 09401117
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Clutch Cover - Black CC-17AB
BOYESEN
$95.95A quality clutch cover protects one of your engine's most critical components while maintaining a clean, professional appearance in the engine bay. The BOYESEN CC-17AB delivers lightweight construction without compromising durability, making it an ideal...09401116- SKU:
- 09401116
- Availability:
- Ships Same Business Day
- Weight:
- 0.74 LBS
- TYPE:
- CLUTCH
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Clutch Cover - Gold CC-10M
BOYESEN
$179.95A factory clutch cover that actually protects your engine while keeping weight down—essential for racers and serious builders who demand both durability and performance. The BOYESEN CC-10M combines precision engineering with a tough finish that handles...09401114- SKU:
- 09401114
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- COLOR/FINISH:
- MAGNESIUM
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$179.95 -
BOYESEN Clutch Cover - Black CC-10B
BOYESEN
$179.95A lightweight clutch cover protects one of your most critical drivetrain components while shedding unnecessary weight from your bike. The BOYESEN CC-10B combines precision engineering with a durable powder coat, keeping your clutch assembly sealed and...09401113- SKU:
- 09401113
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$179.95 -
BOYESEN Clutch Cover - Black CC-06AB
BOYESEN
$95.95A lightweight clutch cover reduces unsprung weight and rotational mass, directly improving throttle response and acceleration. The individually surfaced design eliminates fitment issues and leak-prone gaps that plague stock covers, while the...09401110- SKU:
- 09401110
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- TYPE:
- CLUTCH
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Ignition Cover - Gold SC-30M
BOYESEN
$87.95A quality ignition cover protects critical engine components from moisture, dirt, and debris that compromise reliability and longevity. The BOYESEN SC-30M delivers professional-grade sealing and durability without adding unnecessary weight, making it an...09401108- SKU:
- 09401108
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
$87.95 -
BOYESEN Ignition Cover - Black SC-30B
BOYESEN
$87.95Your engine's internals deserve protection from the elements, and a quality ignition cover is non-negotiable for long-term reliability. The BOYESEN SC-30B Factory Ignition Cover combines OEM-grade engineering with a tough powder-coated finish that...09401107- SKU:
- 09401107
- Availability:
- Ships Same Business Day
- Weight:
- 0.73 LBS
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- MATERIAL:
- ALUMINUM
- TYPE:
- IGNITION
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Ignition Cover - Gold SC10AM
BOYESEN
$87.95A quality ignition cover protects your engine's internal components from moisture, dirt, and debris while giving your bike a professional appearance. The BOYESEN SC10AM Factory Ignition Cover combines OEM-style reliability with superior durability,...09401106- SKU:
- 09401106
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- COLOR/FINISH:
- MAGNESIUM
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
$87.95 -
BOYESEN Ignition Cover - Black SC10AB
BOYESEN
$87.95A quality ignition cover isn't just cosmetic—it's essential protection for your engine's internals against dirt, moisture, and debris that can compromise performance and longevity. The BOYESEN Factory Ignition Cover delivers the durability and precision...09401105- SKU:
- 09401105
- Availability:
- Ships Same Business Day
- Weight:
- 0.68 LBS
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
$87.95 -
BOYESEN Ignition Cover - Gold SC-10DM
BOYESEN
$87.95A clean engine bay starts with proper protection. The BOYESEN Ignition Cover shields your engine's internals from moisture, dirt, and debris while delivering a factory-finished appearance that commands respect. Built from premium cast aluminum with a...09401104- SKU:
- 09401104
- Availability:
- Ships Same Business Day
- Weight:
- 0.73 LBS
- TYPE:
- IGNITION
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
$87.95 -
BOYESEN Ignition Cover - Black SC-10DB
BOYESEN
$87.95Engine covers aren't just aesthetic—they're critical protection against contamination and moisture that can compromise performance and longevity. The BOYESEN Ignition Cover combines OEM-quality construction with a durable powder-coated finish that...09401103- SKU:
- 09401103
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
$87.95 -
BOYESEN Clutch Cover - Black - KX250 CC-12CB
BOYESEN
$95.95A clutch cover that actually protects your engine while keeping weight off your chassis—that's what separates competitive builds from the rest. The BOYESEN Lightweight Clutch Cover combines factory-grade durability with precision manufacturing to...09400389- SKU:
- 09400389
- Availability:
- Ships Same Business Day
- Weight:
- 1.03 LBS
- COLOR/FINISH:
- BLACK
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- COLOR/FINISH:
- POWDER-COATED
- UNITS:
- EACH
- PRODUCT NAME:
- COVER
$95.95 -
BOYESEN Ignition Cover - Gold - YZ125 SC-33AM
BOYESEN
$87.95A factory-quality ignition cover protects your YZ125's internal engine components from dirt, water, and debris while maintaining a professional appearance on the track or trail. Boyesen's cast-aluminum design delivers the durability of OEM parts without...09400384- SKU:
- 09400384
- Availability:
- Ships Same Business Day
- Weight:
- 0.66 LBS
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
$87.95 -
BOYESEN Ignition Cover - Black - YZ125 SC-33AB
BOYESEN
$87.95Factory-level protection starts with a quality ignition cover that seals out dirt and water while withstanding the demands of aggressive riding. The Boyesen SC-33AB delivers OEM aesthetics with superior durability—cast from high-grade aluminum and...09400383- SKU:
- 09400383
- Availability:
- Ships Same Business Day
- Weight:
- 0.66 LBS
- MATERIAL:
- ALUMINUM
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- TYPE:
- IGNITION
$87.95 -
BOYESEN Ignition Cover - Gold - KX250 SC-12AM
BOYESEN
$87.95The stock ignition cover on your KX250 SC-12AM is vulnerable to the elements—dirt, water, and constant vibration take their toll. A quality replacement cover like the BOYESEN protects your engine's internal components while giving your bike a...09400381- SKU:
- 09400381
- Availability:
- Ships Same Business Day
- Weight:
- 0.59 LBS
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
$87.95 -
BOYESEN Ignition Cover - Black - XR/CRF50/70 SC-05B
BOYESEN
$109.95A properly sealed ignition cover protects your engine's internals from dirt, water, and debris—critical for reliability whether you're racing or riding casually. The Boyesen Factory Ignition Cover delivers the protection of OEM engineering with materials...09400377- SKU:
- 09400377
- Availability:
- Ships Same Business Day
- Weight:
- 1.19 LBS
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- RIDING STYLE:
- STREET
$109.95 -
BOYESEN Impeller/Waterpump Cover - Magnesium WPK-07M
BOYESEN
$194.95Engine cooling efficiency directly impacts performance, reliability, and longevity—especially under sustained racing conditions or high-load operation. The BOYESEN WPK-07M water pump cover and impeller upgrade increases coolant flow across all RPM...09400263- SKU:
- 09400263
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- MODEL:
- SUPERCOOLER
- TYPE:
- WATER PUMP
- COLOR/FINISH:
- POWDER-COATED
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$194.95
