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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Pro Circuit Replacement O-Ring for 2004 Kawasaki KX250F and RM-Z250 PC4008-0401
PRO CIRCUIT
$5.95A failing water pump seal compromises cooling system integrity and risks catastrophic engine damage on the track or trail. The PRO CIRCUIT PC4008-0401 replacement O-ring restores OEM-spec sealing performance, eliminating leaks and maintaining optimal...09350003- SKU:
- 09350003
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- RIDING STYLE:
- OFF-ROAD
- APPLICATION:
- WATER PUMP
- PRODUCT NAME:
- O-RING
- UNITS:
- EACH
$5.95 -
Pro Circuit Clutch Cover Kawasaki KX250F 2004-2008 CCK04250
PRO CIRCUIT
$173.95The Pro Circuit Clutch Cover combines aerospace-grade durability with thermal management—critical for maintaining consistent clutch engagement during extended high-RPM sessions. T-6 aircraft aluminum construction reduces unsprung mass while dissipating...09400467- SKU:
- 09400467
- Availability:
- Ships Same Business Day
- Weight:
- 0.46 LBS
- COLOR/FINISH:
- BLACK
- MATERIAL:
- T-6 ALUMINUM
- PRODUCT NAME:
- COVER
- UNITS:
- EACH
- COLOR/FINISH:
- ALUMINUM
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH
$173.95 -
Pro Circuit Water Pump Cover with Impeller for Kawasaki KX250 2019-2020 WPK17250
PRO CIRCUIT
$239.95Engine cooling directly impacts your KX250's reliability and peak performance—especially under sustained high-RPM racing conditions. A stock water pump cover often allows cavitation and inefficient flow, leading to hot spots and premature wear. The Pro...09401611- SKU:
- 09401611
- Availability:
- Ships Same Business Day
- Weight:
- 0.71 LBS
- COLOR/FINISH:
- MACHINED
- PRODUCT NAME:
- COVER
- UNITS:
- SET
- TYPE:
- WATER PUMP
- COLOR/FINISH:
- ANODIZED
- MATERIAL:
- BILLET ALUMINUM
- RIDING STYLE:
- OFF-ROAD
$239.95 -
MOOSE RACING Countershaft Sprocket Seal Kit - KTM 25-4002
MOOSE RACING
$23.95The countershaft sprocket seal is a critical wear component that directly impacts drivetrain longevity and performance. Premature seal failure allows dirt and moisture ingress, leading to accelerated bearing wear and potential drivetrain damage. This...09350429- SKU:
- 09350429
- Availability:
- Ships Same Business Day
- Weight:
- 0.21 LBS
- PRODUCT NAME:
- SEAL KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- COUNTERSHAFT
$23.95Qty in Cart: 0Quantity:Price:$23.95Subtotal: -
MOOSE RACING Countershaft Sprocket Seal Kit - KTM 25-4004
MOOSE RACING
$39.95Countershaft seals are critical wear items that directly impact engine longevity and reliability. A failing seal allows transmission fluid to leak and contamination to enter, compromising shift quality and accelerating component wear. The MOOSE RACING...09350431- SKU:
- 09350431
- Availability:
- Ships Same Business Day
- Weight:
- 0.16 LBS
- APPLICATION:
- COUNTERSHAFT
- RIDING STYLE:
- STREET
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SEAL KIT
- UNITS:
- KIT
$39.95 -
MOOSE RACING Countershaft Sprocket Seal Kit - Yamaha 25-4022
MOOSE RACING
$23.95Countershaft seals are critical wear points that directly impact engine reliability and transmission performance. A failing seal allows contamination and fluid loss, compromising your engine's longevity and power delivery. This OEM-quality seal kit from...09350447- SKU:
- 09350447
- Availability:
- Ships Same Business Day
- Weight:
- 0.19 LBS
- RIDING STYLE:
- OFF-ROAD
- APPLICATION:
- COUNTERSHAFT
- PRODUCT NAME:
- SEAL KIT
- UNITS:
- KIT
$23.95Qty in Cart: 0Quantity:Price:$23.95Subtotal: -
MOOSE RACING Inner Clutch Cover Gasket 816099
MOOSE RACING
$19.22A leaking clutch cover gasket compromises engine sealing and can lead to oil contamination and performance degradation. The MOOSE RACING Inner Clutch Cover Gasket (816099) delivers OEM-equivalent reliability at a fraction of OEM pricing, using high-tech...09346121- SKU:
- 09346121
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
- PRODUCT NAME:
- GASKET
- UNITS:
- EACH
$19.22 -
MOOSE RACING Inner Clutch Cover Gasket 816130
MOOSE RACING
$8.55A failing clutch cover gasket leads to oil leakage, contamination, and potential engine damage—exactly what you can't afford during competition or a critical rebuild. The MOOSE RACING Inner Clutch Cover Gasket delivers OEM-equivalent sealing performance...09346122- SKU:
- 09346122
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
- PRODUCT NAME:
- GASKET
- UNITS:
- EACH
$8.55 -
MOOSE RACING Inner Clutch Cover Gasket 816138
MOOSE RACING
$13.91Clutch cover gasket failures lead to oil seepage, loss of compression, and potential engine damage—especially critical if you're running a rebuilt or high-mileage engine. The MOOSE RACING Inner Clutch Cover Gasket delivers OEM-equivalent sealing...09346123- SKU:
- 09346123
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
- UNITS:
- EACH
- PRODUCT NAME:
- GASKET
$13.91Qty in Cart: 0Quantity:Price:$13.91Subtotal: -
MOOSE RACING Inner Clutch Cover Gasket 816149
MOOSE RACING
$12.69A leaking clutch cover gasket compromises engine sealing and invites oil contamination into your clutch assembly—a costly problem if left unaddressed. The MOOSE RACING Inner Clutch Cover Gasket delivers OEM-specification sealing at a fraction of OEM...09346124- SKU:
- 09346124
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CLUTCH COVER
- UNITS:
- EACH
- PRODUCT NAME:
- GASKET
$12.69 -
MOOSE RACING Motor Gasket Kit with Seal - Husqvarna/KTM 811373
MOOSE RACING
$179.68A complete engine and transmission rebuild demands precision-fit gaskets and seals that won't compromise durability or reliability. This MOOSE RACING kit eliminates the frustration of sourcing individual components at inflated OEM prices, giving you...09345369- SKU:
- 09345369
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- PRODUCT NAME:
- GASKET
- UNITS:
- KIT
- TYPE:
- ENGINE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
$179.68Qty in Cart: 0Quantity:Price:$179.68Subtotal: -
MOOSE RACING Motor Gasket Kit with Seal - Husqvarna/KTM 811374
MOOSE RACING
$145.13A complete engine and transmission rebuild demands precision-fit gaskets and seals—any compromise on fit or material quality risks oil leaks, compression loss, and premature wear. The MOOSE RACING Motor Gasket Kit delivers OEM-equivalent performance at a...09345370- SKU:
- 09345370
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- GASKET
- RIDING STYLE:
- STREET
- TYPE:
- ENGINE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
$145.13Qty in Cart: 0Quantity:Price:$145.13Subtotal: -
MOOSE RACING Motor Gasket Kit with Seal - Kawasaki 811485
MOOSE RACING
$200.43A complete engine and transmission rebuild demands precision-fit gaskets and seals you can trust—and OEM replacements often carry premium pricing that doesn't reflect the part's actual value. The MOOSE RACING Motor Gasket Kit delivers genuine...09345371- SKU:
- 09345371
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- TYPE:
- COMPLETE
- PRODUCT NAME:
- GASKET
- TYPE:
- ENGINE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$200.43 -
MOOSE RACING Motor Gasket Kit with Seal - KTM 811976
MOOSE RACING
$163.23A complete engine and transmission rebuild demands precision gaskets and seals that won't compromise your tolerances or leak under load. MOOSE Racing Motor Gasket Kits deliver OEM-equivalent performance at a fraction of the cost, giving you the...09345372- SKU:
- 09345372
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- TYPE:
- ENGINE
- PRODUCT NAME:
- GASKET
- RIDING STYLE:
- STREET
- UNITS:
- KIT
$163.23 -
MOOSE RACING Complete Motor Gasket Kit - TC125 8080009
MOOSE RACING
$77.45A complete engine and transmission rebuild demands precision gaskets and seals that won't fail under load or high RPM cycles. The MOOSE RACING Complete Motor Gasket Kit eliminates the frustration of sourcing individual components by bundling everything...09346437- SKU:
- 09346437
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- TYPE:
- ENGINE
- TYPE:
- COMPLETE
- PRODUCT NAME:
- GASKET
$77.45 -
MOOSE RACING Complete Motor Gasket Kit without Seals - CRF450 8110035
MOOSE RACING
$150.96A complete engine rebuild demands precision gaskets that won't compromise reliability—OEM quality shouldn't require OEM pricing. This Moose Racing kit delivers comprehensive coverage for both engine and transmission, engineered to exact specifications so...09346454- SKU:
- 09346454
- Availability:
- Ships Same Business Day
- Weight:
- 0.46 LBS
- PRODUCT NAME:
- GASKET
- RIDING STYLE:
- STREET
- TYPE:
- ENGINE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
$150.96Qty in Cart: 0Quantity:Price:$150.96Subtotal: -
MOOSE RACING Head Cover Gasket - Honda 819199
MOOSE RACING
$64.67Head cover gaskets are prone to deterioration over time, leading to oil leaks that compromise engine cleanliness and performance. OEM replacements come at a premium, but MOOSE Racing delivers genuine-quality gaskets at a fraction of the cost—without...09346456- SKU:
- 09346456
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- GASKET
- MATERIAL:
- RUBBER
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- HEAD COVER
- UNITS:
- EACH
$64.67 -
MOOSE RACING Valve Shim - 8.90 x 2.24 - 5 pack MSE5PK890224
MOOSE RACING
$10.95Maintaining precise valve clearances is critical to engine reliability and performance, and having the right shims on hand eliminates costly downtime during valve train service. MOOSE Racing valve shims are forged from 4140 cold-rolled steel—not...09261918- SKU:
- 09261918
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- UNITS:
- 5 PACK
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- TYPE:
- VALVE
- MATERIAL:
- ROLLED
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 2.24 MM
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
$10.95 -
MOOSE RACING Valve Shim - 8.90 x 2.32 - 5 pack MSE5PK890232
MOOSE RACING
$10.95Valve shim maintenance is critical to valve train precision, and having quality refill shims on hand eliminates downtime during adjustments. These MOOSE RACING shims are forged from 4140 cold-rolled steel—not sintered—ensuring consistent hardness and...09261920- SKU:
- 09261920
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- MATERIAL:
- ROLLED
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.32 MM
$10.95 -
MOOSE RACING Valve Shim - 8.90 x 2.36 - 5 pack MSE5PK890236
MOOSE RACING
$10.95Precision valve train maintenance demands the right shims on hand—and these MOOSE RACING forged steel shims eliminate guesswork during critical adjustments. Whether you're dialing in clearances on a race engine or maintaining a high-mileage build, having...09261921- SKU:
- 09261921
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.36 MM
- MATERIAL:
- ROLLED
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
$10.95
