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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On Sale
Wossner 53.96mm Piston Kit for Honda CR125R 1992-1999 8020DB
WOSSNER
MSRP: $122.00Now: $115.90Was: $122.00A worn or damaged piston compromises combustion efficiency, increases friction losses, and accelerates wear on your entire top-end assembly. The Wossner 8020DB delivers a complete, ready-to-install...09104723- SKU:
- 09104723
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- BORE - OVERSIZE METRIC:
- +0.01 MM
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- SINGLE RING
- UNITS:
- KIT
- BORE - OVERSIZE:
- +0,01 MM
- BORE SIZE METRIC:
- 54.01 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- PISTON SIZE METRIC:
- 53.96 MM
- DISPLACEMENT:
- 125 CC
- MODEL:
- STANDARD SERIES
- PRODUCT NAME:
- PISTON KIT
MSRP: $122.00Now: $115.90Was: $122.00Qty in Cart: 0Quantity:Price:MSRP: $122.00Now: $115.90Was: $122.00Subtotal: -
On Sale
Wossner Piston Kit 66.37mm Yamaha YZ250 1999-2023 8216DC
WOSSNER
MSRP: $152.00Now: $144.40Was: $152.00The Wossner Piston Kit 8216DC is engineered specifically for Yamaha YZ250 engines, delivering the reliability and precision you need to maintain peak performance across thousands of combustion cycles...09104879- SKU:
- 09104879
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- BORE - OVERSIZE:
- +0,02 MM
- BORE - OVERSIZE METRIC:
- +0.02 MM
- MODEL:
- STANDARD SERIES
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 66.42 MM
- PISTON MATERIAL:
- FORGED
- UNITS:
- KIT
- DISPLACEMENT:
- 249 CC
- TYPE:
- DUAL RING
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- 66.37 MM
- RIDING STYLE:
- OFF-ROAD
MSRP: $152.00Now: $144.40Was: $152.00 -
On Sale
Wossner Piston Kit 44.98mm KTM 65 SX 2009-2023 8241DC
WOSSNER
MSRP: $102.00Now: $96.90Was: $102.00Stock pistons are a weak link in high-demand 2-stroke engines, especially when pushing a KTM 65 SX to its limits. The Wossner 8241DC delivers the durability and precision engineering needed for...09104892- SKU:
- 09104892
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- BORE - OVERSIZE METRIC:
- +0.02 MM
- MODEL:
- STANDARD SERIES
- PISTON SIZE METRIC:
- 44.98 MM
- PRODUCT NAME:
- PISTON KIT
- ENGINE TYPE:
- 2-STROKE
- TYPE:
- SINGLE RING
- BORE - OVERSIZE:
- +0,02 MM
- PISTON MATERIAL:
- FORGED
- UNITS:
- KIT
- BORE SIZE METRIC:
- 45.04 MM
- DISPLACEMENT:
- 64 CC
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
MSRP: $102.00Now: $96.90Was: $102.00Qty in Cart: 0Quantity:Price:MSRP: $102.00Now: $96.90Was: $102.00Subtotal: -
On Sale
Wossner Single Ring Piston Kit Kawasaki KX125 1990 8106DA
WOSSNER
MSRP: $117.95Now: $112.05Was: $117.95A piston kit is the heart of 2-stroke performance—worn or inadequate pistons directly limit power delivery, increase blow-by, and accelerate engine wear. The Wossner 8106DA is engineered to restore...09105531- SKU:
- 09105531
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- BORE SIZE METRIC:
- 56.00 MM
- DISPLACEMENT:
- 124 CC
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- SINGLE RING
- UNITS:
- KIT
- PISTON SIZE METRIC:
- 55.94 MM
- BORE - OVERSIZE:
- STANDARD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- BORE - OVERSIZE METRIC:
- STANDARD
- MODEL:
- STANDARD SERIES
- PRODUCT NAME:
- PISTON KIT
MSRP: $117.95Now: $112.05Was: $117.95Qty in Cart: 0Quantity:Price:MSRP: $117.95Now: $112.05Was: $117.95Subtotal: -
On Sale
Wossner Piston Kit Yamaha YZ250 1988-1991 68.44mm 8134D050
WOSSNER
MSRP: $152.00Now: $144.40Was: $152.00A worn or damaged piston directly undermines your YZ250's power delivery, throttle response, and engine longevity. This Wossner kit restores—or significantly upgrades—your 2-stroke's performance with...09105547- SKU:
- 09105547
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- DISPLACEMENT:
- 246 CC
- MODEL:
- STANDARD SERIES
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- DUAL RING
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- PISTON SIZE METRIC:
- 68.44 MM
- BORE - OVERSIZE METRIC:
- +0.50 MM
- BORE SIZE METRIC:
- 68.50 MM
- BORE - OVERSIZE:
- +0,50 MM
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $152.00Now: $144.40Was: $152.00Qty in Cart: 0Quantity:Price:MSRP: $152.00Now: $144.40Was: $152.00Subtotal: -
On Sale
Wossner Yamaha YZ250 1988-1991 68.94mm Piston Kit 8134D100
WOSSNER
MSRP: $152.00Now: $144.40Was: $152.00The Wossner YZ250 piston kit delivers the precision engineering your 2-stroke engine demands, whether you're chasing lap times or rebuilding after hard use. This complete kit—piston, rings, pin, and...09105548- SKU:
- 09105548
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- BORE - OVERSIZE:
- +1,00 MM
- DISPLACEMENT:
- 246 CC
- MODEL:
- STANDARD SERIES
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- DUAL RING
- BORE - OVERSIZE METRIC:
- +1.00 MM
- BORE SIZE METRIC:
- 69.00 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- PISTON SIZE METRIC:
- 68.94 MM
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $152.00Now: $144.40Was: $152.00Qty in Cart: 0Quantity:Price:MSRP: $152.00Now: $144.40Was: $152.00Subtotal: -
On Sale
Wossner Piston Kit 67.94mm 2-Stroke 246cc 8134DA
WOSSNER
MSRP: $152.00Now: $144.40Was: $152.00If you're running a 246cc 2-stroke at the limit, piston failure isn't an option—it's a catastrophe. The Wossner 8134DA delivers German-engineered reliability with a complete kit that eliminates...09105551- SKU:
- 09105551
- Availability:
- Ships Same Business Day
- Weight:
- 0.76 LBS
- DISPLACEMENT:
- 246 CC
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- 67.94 MM
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- DUAL RING
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE SIZE METRIC:
- 68.00 MM
- MODEL:
- STANDARD SERIES
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE:
- STANDARD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
MSRP: $152.00Now: $144.40Was: $152.00Qty in Cart: 0Quantity:Price:MSRP: $152.00Now: $144.40Was: $152.00Subtotal: -
Wrench Rabbit Engine Rebuild Kit for KTM 125 SX 2007-2015 WR101-216
WRENCH RABBIT
$1,013.95When your KTM 125 SX's engine reaches the end of its service life, a quality rebuild kit saves you time and ensures consistent performance across all critical components. The Wrench Rabbit Engine...09031102- SKU:
- 09031102
- Availability:
- Ships Same Business Day
- Weight:
- 11.55 LBS
- ENGINE TYPE:
- 2-STROKE
- MODEL:
- WRENCH RABBIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- FEATURES:
- STANDARD COMPRESSION PISTON
- PRODUCT NAME:
- REBUILD KIT
- TYPE:
- ENGINE
$1,013.95Qty in Cart: 0Quantity:Price:$1,013.95Subtotal: -
Wrench Rabbit Complete Engine Rebuild Kit for Yamaha YZ85 2002-2016 WR101-089
WRENCH RABBIT
$1,183.95When your Yamaha YZ85 two-stroke demands a full rebuild, settling for mismatched components invites premature wear and unpredictable performance. The Wrench Rabbit Complete Engine Rebuild Kit...09031116- SKU:
- 09031116
- Availability:
- Ships Same Business Day
- Weight:
- 13.25 LBS
- FEATURES:
- STANDARD COMPRESSION PISTON
- PRODUCT NAME:
- REBUILD KIT
- TYPE:
- ENGINE
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- MODEL:
- WRENCH RABBIT
- RIDING STYLE:
- OFF-ROAD
$1,183.95 -
Wrench Rabbit Complete Engine Rebuild Kit for 2013 Suzuki RMZ450 WR101-149
WRENCH RABBIT
$1,156.95A complete engine rebuild kit removes the guesswork from top and bottom-end work on your 2013 Suzuki RMZ450. Rather than sourcing individual components from multiple suppliers, this Wrench Rabbit kit...09031118- SKU:
- 09031118
- Availability:
- Ships Same Business Day
- Weight:
- 15.00 LBS
- FEATURES:
- STANDARD COMPRESSION PISTON
- PRODUCT NAME:
- REBUILD KIT
- TYPE:
- ENGINE
- ENGINE TYPE:
- 4-STROKE
- MODEL:
- WRENCH RABBIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$1,156.95Qty in Cart: 0Quantity:Price:$1,156.95Subtotal: -
Wrench Rabbit Engine Rebuild Kit for 2013-2016 Honda CRF450R WR101-150
WRENCH RABBIT
$1,132.95When your Honda CRF450R engine hits its limits, a complete rebuild is the only way to restore full performance and reliability. The Wrench Rabbit Engine Rebuild Kit bundles every critical component...09031119- SKU:
- 09031119
- Availability:
- Ships Same Business Day
- Weight:
- 16.30 LBS
- FEATURES:
- STANDARD COMPRESSION PISTON
- PRODUCT NAME:
- REBUILD KIT
- TYPE:
- ENGINE
- ENGINE TYPE:
- 4-STROKE
- MODEL:
- WRENCH RABBIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$1,132.95 -
BOYESEN Ignition Cover - Black - CR250 SC-02AB
BOYESEN
$87.95Factory Ignition Cover SC02AB Professional appearance enhances your bike's aesthetics. Seals effectively to protect the engine from dirt and water. Durable design outlasts standard stock...SC02AB- SKU:
- SC02AB
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
- UNITS:
- EACH
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Impeller Water Pump - Magnesium - YZ125 WPK-31AM
BOYESEN
$219.95Stock water pumps can't keep pace with a high-revving YZ125, leaving your engine vulnerable to thermal stress and performance loss. The Boyesen Impeller upgrade delivers measurably higher coolant...09401472- SKU:
- 09401472
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- COLOR/FINISH:
- GOLD
- MODEL:
- SUPERCOOLER
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- NAUTILUS
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- PRODUCT NAME:
- IMPELLER
- BASE COLOR:
- GOLD
$219.95Qty in Cart: 0Quantity:Price:$219.95Subtotal: -
BOYESEN Ignition Cover - Gold SC-41M
BOYESEN
$87.95Engine covers aren't just cosmetic—they're critical protection against dirt, moisture, and debris that can compromise internal engine components. The BOYESEN Ignition Cover delivers the durability...09400700- SKU:
- 09400700
- Availability:
- Ships Same Business Day
- Weight:
- 0.71 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- RIDING STYLE:
- STREET
- UNITS:
- EACH
$87.95Qty in Cart: 0Quantity:Price:$87.95Subtotal: -
BOYESEN Clutch Cover - Gold - CR250/500 CC-02M
BOYESEN
$95.95A lightweight clutch cover is essential for reducing unsprung weight and improving your bike's overall power-to-weight ratio—critical gains on the track where every fraction matters. The BOYESEN...09400222- SKU:
- 09400222
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- COLOR/FINISH:
- MAGNESIUM
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- FACTORY RACING
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
$95.95Qty in Cart: 0Quantity:Price:$95.95Subtotal: -
BOYESEN Ignition Cover - Gold - CR250 SC-02M
BOYESEN
$87.95A factory-quality ignition cover protects your CR250's engine from the elements while maintaining that professional appearance in the pits or on the track. Boyesen's cast aluminum construction...09400210- SKU:
- 09400210
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
- COLOR/FINISH:
- MAGNESIUM
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- COVER
- MODEL:
- FACTORY RACING
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- IGNITION
- UNITS:
- EACH
$87.95 -
BOYESEN Ignition Gasket Cover - KTM SCG-40A
BOYESEN
$5.95Factory-grade ignition covers aren't just about aesthetics—they're essential protection for your engine's internals against dirt, moisture, and debris that can compromise performance and longevity...09343123- SKU:
- 09343123
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- TYPE:
- IGNITION COVER
- PRODUCT NAME:
- GASKET
- RIDING STYLE:
- OFF-ROAD
- MATERIAL:
- NITRILE RUBBER
- MODEL:
- FACTORY RACING
- UNITS:
- EACH
$5.95Qty in Cart: 0Quantity:Price:$5.95Subtotal: -
BOYESEN Impeller/Waterpump Cover - Orange WPK-44AO
BOYESEN
$199.95Engine temperature management is critical to longevity and consistent performance, especially under sustained load or high-RPM operation. The Boyesen WPK-44AO improves coolant circulation across all...09320156- SKU:
- 09320156
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- POWDER-COATED
- TYPE:
- WATER PUMP
- COLOR/FINISH:
- ORANGE
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- UNITS:
- KIT
- MATERIAL:
- ALUMINUM
- BASE COLOR:
- ORANGE
- RIDING STYLE:
- OFF-ROAD
$199.95Qty in Cart: 0Quantity:Price:$199.95Subtotal: -
HOT RODS Seal Output Shaft OSK0039
HOT RODS
$35.95A leaking countershaft seal compromises transmission integrity and can lead to costly damage if left unaddressed. The HOT RODS Seal Output Shaft Kit (OSK0039) gives you everything needed for a...09350561- SKU:
- 09350561
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- SEAL
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$35.95Qty in Cart: 0Quantity:Price:$35.95Subtotal: -
HOT RODS Seal Output Shaft OSK0048
HOT RODS
$13.95A leaking countershaft seal will compromise your engine's integrity and waste no time turning a minor issue into catastrophic damage. This complete HOT RODS seal kit eliminates the guesswork by...09350563- SKU:
- 09350563
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$13.95
