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!
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- Quantity
- Price
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On Sale
COMETIC Bottom End Gasket Set C3299
COMETIC
MSRP: $15.95Now: $14.36Was: $15.95Engine seals and gaskets are critical wear items that degrade with heat cycles and age—compromised bottom end gaskets lead to oil leaks, contamination, and catastrophic engine failure. The COMETIC...09342514- SKU:
- 09342514
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- GASKET KIT
- MODEL:
- HI-PERFORMANCE
- TYPE:
- BOTTOM END
- BORE SIZE METRIC:
- 55.00 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $15.95Now: $14.36Was: $15.95 -
On Sale
ATHENA Complete Gasket Kit - KTM P400270850019
ATHENA
MSRP: $142.95Now: $129.00Was: $142.95A complete engine rebuild demands gaskets that can handle extreme temperatures and sustained pressure without compromise. Athena's engineering ensures reliable sealing across all critical surfaces,...09341819- SKU:
- 09341819
- Availability:
- Ships Same Business Day
- Weight:
- 0.49 LBS
- RIDING STYLE:
- STREET
- TYPE:
- COMPLETE
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- GASKET KIT
MSRP: $142.95Now: $129.00Was: $142.95 -
Cylinder Works Standard Bore Cylinder Kit for Polaris RZR 900 2015-2016 60004
CYLINDER WORKS
$672.95The stock cylinder in your Polaris RZR 900 can wear rapidly under aggressive riding conditions, leading to power loss and increased friction. The Cylinder Works Standard Bore Cylinder Kit restores...09310733- SKU:
- 09310733
- Availability:
- Ships Same Business Day
- Weight:
- 7.15 LBS
- CYLINDER DIAMETER METRIC:
- 93.00 MM
- UNITS:
- EACH
- ENGINE TYPE:
- 4-CYCLE
- PRODUCT NAME:
- CYLINDER
- CYLINDER DIAMETER:
- 93,00 MM
- RIDING STYLE:
- UTV
- STYLE:
- STANDARD
$672.95 -
Cylinder Works Suzuki RM-Z250 2010-2012 Standard Bore Cylinder Kit 40004-K01
CYLINDER WORKS
$704.95When your RM-Z250 cylinder shows signs of wear—scoring, loss of compression, or increased blow-by—a factory replacement often means sending your engine out for expensive machine work and re-plating...09310343- SKU:
- 09310343
- Availability:
- Ships Same Business Day
- Weight:
- 3.25 LBS
- COMPRESSION RATIO IMPERIAL:
- 13.4:1
- CYLINDER DIAMETER METRIC:
- 77.00 MM
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- STANDARD
- DISPLACEMENT:
- 249 CC
- ENGINE TYPE:
- 4-CYCLE
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- CYLINDER DIAMETER:
- 77,00 MM
- PRODUCT NAME:
- CYLINDER KIT
- UNITS:
- KIT
$704.95 -
Cylinder Works Kawasaki KX250F 2009 Standard Bore Cylinder Kit 30004-K01
CYLINDER WORKS
$679.95A worn or damaged cylinder compromises both power delivery and reliability—especially critical on a high-strung 250F that demands precision. This bolt-on Cylinder Works kit restores your engine to...09310277- SKU:
- 09310277
- Availability:
- Ships Same Business Day
- Weight:
- 3.15 LBS
- COMPRESSION RATIO IMPERIAL:
- 13.2:1
- CYLINDER DIAMETER METRIC:
- 77.00 MM
- RIDING STYLE:
- OFF-ROAD
- DISPLACEMENT:
- 249 CC
- ENGINE TYPE:
- 4-CYCLE
- STYLE:
- STANDARD
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- CYLINDER DIAMETER:
- 77,00 MM
- PRODUCT NAME:
- CYLINDER KIT
- UNITS:
- KIT
$679.95 -
Hot Cams Valve Shim 9.48 x 2.80 for Honda CRF450R 2002-2014 5PK948280
HOT CAMS
$10.95Valve clearance directly impacts combustion efficiency, engine longevity, and power delivery—and shims are the most reliable way to dial in precise adjustments on your CRF450R. Whether you're...09261404- SKU:
- 09261404
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.80 MM
- RIDING STYLE:
- STREET
- MATERIAL:
- STEEL
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
$10.95 -
Hot Cams Valve Shim 9.48mm x 2.75mm for Honda CRF450R 2002-2014 5PK948275
HOT CAMS
$10.95Valve clearance directly impacts combustion efficiency, fuel economy, and engine longevity—and worn or incorrect shims will throw off those critical tolerances. The Hot Cams 9.48mm x 2.75mm shim pack...09261403- SKU:
- 09261403
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- MATERIAL:
- STEEL
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.75 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
$10.95 -
Hot Cams Valve Shim 9.48 x 2.70 for Honda CRF450R 2002-2014 5PK948270
HOT CAMS
$10.95Valve clearance directly impacts engine efficiency, fuel atomization, and overall performance—and worn or incorrect shims throw off that critical tolerance. The HOT CAMS Valve Shim 9.48 x 2.70 mm...09261402- SKU:
- 09261402
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- TYPE:
- VALVE
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.70 MM
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- MATERIAL:
- STEEL
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
$10.95 -
Hot Cams Valve Shim 9.48mm x 2.50mm for Honda CRF 450R 2002-2014 5PK948250
HOT CAMS
$10.95Valve clearance directly impacts combustion efficiency, valve longevity, and overall engine reliability—especially in high-performance applications where tolerances are critical. This HOT CAMS shim...09261398- SKU:
- 09261398
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- UNITS:
- 5 PACK
- VALVE SHIM THICKNESS METRIC:
- 2.50 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- TYPE:
- VALVE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
$10.95 -
Hot Cams Valve Shim 8.90mm x 2.12mm KTM 250 SX-F 2005-2011 5PK890212
HOT CAMS
$11.95Valve clearance drift is inevitable on high-revving four-strokes like the KTM 250 SX-F—even small deviations compromise combustion efficiency and can lead to bent valves or loss of power. These Hot...09261359- SKU:
- 09261359
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- MATERIAL:
- STEEL
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.12 MM
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
$11.95 -
Hot Cams Valve Shim 8.90 x 2.08 KTM 250 SX-F 2005 5PK890208
HOT CAMS
$11.95Proper valve clearance is critical to engine longevity and performance—too tight and you risk valve float; too loose and you lose efficiency. Hot Cams valve shims are precision-engineered to maintain...09261358- SKU:
- 09261358
- Availability:
- Ships Same Business Day
- Weight:
- 0.03 LBS
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- RIDING STYLE:
- STREET
- MATERIAL:
- STEEL
- OUTSIDE DIAMETER METRIC:
- 8.90 MM
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.08 MM
$11.95 -
Hot Cams Valve Shim 7.48mm x 2.90mm for Honda CRF 150R 2007-2018 5PK748290
HOT CAMS
$10.95Proper valve clearance is critical to engine longevity and performance—too tight and you risk valve damage, too loose and you lose compression and efficiency. The Hot Cams Valve Shim 7.48 x 2.90...09261336- SKU:
- 09261336
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- MATERIAL:
- STEEL
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- RIDING STYLE:
- SNOW
- VALVE SHIM THICKNESS METRIC:
- 2.90 MM
$10.95 -
Hot Cams Valve Shim 7.48mm x 2.75mm for Honda CRF 150R 2007-2018 5PK748275
HOT CAMS
$10.95Valve shim wear is one of the most overlooked maintenance items that directly impacts engine performance and longevity. If your Honda CRF 150R is experiencing rough idle, valve noise, or loss of...09261333- SKU:
- 09261333
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- TYPE:
- VALVE
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 2.75 MM
- MATERIAL:
- STEEL
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
$10.95 -
Hot Cams Valve Shim 7.48mm x 2.65mm for Honda CRF150R 2007-2018 5PK748265
HOT CAMS
$10.95Valve clearance drift is inevitable—even small deviations reduce power output and increase wear on your top-end. These HOT CAMS valve shims restore precise clearance tolerances, bringing your CRF150R...09261331- SKU:
- 09261331
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- PRODUCT NAME:
- SHIM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.65 MM
$10.95 -
Hot Cams Valve Shim 7.48mm x 1.30mm for Honda CBR600RR 2003-2007 5PK748130
HOT CAMS
$10.95Valve clearance drift is inevitable with engine use—improper clearance kills power, increases noise, and accelerates wear on your valvetrain. Hot Cams valve shims deliver precision adjustment to...09261304- SKU:
- 09261304
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- VALVE SHIM THICKNESS METRIC:
- 1.30 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM
- UNITS:
- 5 PACK
- TYPE:
- VALVE
$10.95 -
Hot Cams Cam Chain for Suzuki RM-Z450 2005-2024 HC82RH2010124
HOT CAMS
$63.95A worn or stock cam chain can introduce unwanted slack and noise into your RM-Z450's valve train, compromising both reliability and peak performance at high RPM. The HOT CAMS HC82RH2010124 delivers...09250760- SKU:
- 09250760
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- CHAIN SIZE:
- 82RH2010
- COLOR/FINISH:
- RAW
- MATERIAL:
- STEEL
- UNITS:
- EACH
- MODEL:
- SILENT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- CAM
- PRODUCT NAME:
- CHAIN
- BASE FINISH:
- RAW
$63.95 -
HOT RODS Crank Bearings K012
HOT RODS
$113.95A crankshaft is only as reliable as its bearings. The HOT RODS K012 crank bearing and seal kit ensures proper load distribution, oil pressure integrity, and long-term durability when you're running a...09240034- SKU:
- 09240034
- Availability:
- Ships Same Business Day
- Weight:
- 1.42 LBS
- APPLICATION:
- MAIN CRANKSHAFT
- UNITS:
- KIT
- TYPE:
- BALL
- PRODUCT NAME:
- BEARING
- RIDING STYLE:
- OFF-ROAD
$113.95 -
On Sale
ATHENA Connecting Rod Kit P40321046
ATHENA
MSRP: $126.95Now: $114.00Was: $126.95The ATHENA Connecting Rod Kit P40321046 delivers the precision and durability your engine demands when power levels climb. Built to OEM material standards but engineered with high-frequency surface...09230490- SKU:
- 09230490
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- DISPLACEMENT:
- 300 CC
- PRODUCT NAME:
- CONNECTING ROD KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- DISPLACEMENT:
- 250 CC
- RIDING STYLE:
- STREET
MSRP: $126.95Now: $114.00Was: $126.95 -
On Sale
ATHENA Connecting Rod Kit P40321039
ATHENA
MSRP: $98.95Now: $89.00Was: $98.95The ATHENA Connecting Rod Kit P40321039 delivers the reliability and precision your engine demands at high RPM. Built with materials engineered to match OEM specifications, these rods handle extreme...09230485- SKU:
- 09230485
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- DISPLACEMENT:
- 65 CC
- PRODUCT NAME:
- CONNECTING ROD KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $98.95Now: $89.00Was: $98.95 -
HOT RODS Crankshaft Kit 4416
HOT RODS
$489.95If you're building a long-stroke engine for your ATV, the HOT RODS Crankshaft Kit 4416 eliminates the guesswork and machine work typically required for displacement increases. This complete assembly...09210516- SKU:
- 09210516
- Availability:
- Ships Same Business Day
- Weight:
- 6.95 LBS
- COLOR/FINISH:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- DISPLACEMENT:
- 250 CC
- PRODUCT NAME:
- CRANKSHAFT ASSEMBLY
- STROKE LENGTH METRIC:
- 53.60 MM
- MATERIAL:
- 4140 STEEL
- UNITS:
- ASSEMBLY
- FEATURES:
- STANDARD CRANKSHAFT
- MODEL:
- 4-CYCLE
- TYPE:
- OEM STROKE
$489.95
