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
JAMES GASKET Thermostat O-Ring 10969
JAMES GASKET
Now: $4.00Was: $8.60A failing thermostat o-ring is one of the easiest ways to develop coolant leaks that go undetected until serious engine damage occurs. The JAMES GASKET Thermostat O-Ring 10969 is a precision-engineered replacement that restores a reliable seal at the...09351087- SKU:
- 09351087
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- TYPE:
- THERMOSTAT
- PRODUCT NAME:
- O-RING
- RIDING STYLE:
- STREET
- UNITS:
- 5 PACK
Now: $4.00Was: $8.60 -
On Sale
JAMES GASKET Cylinder Head Gasket ST-16500085
JAMES GASKET
MSRP: $97.95Now: $63.00Was: $97.95A quality cylinder head gasket is critical to maintaining combustion sealing and preventing costly coolant or oil leaks. The JAMES GASKET ST-16500085 is a genuine OEM-equivalent kit engineered to factory specifications, ensuring reliable performance...09346474- SKU:
- 09346474
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- MATERIAL:
- -
- RIDING STYLE:
- STREET
- THICKNESS IMPERIAL:
- 0,045'
- BORE SIZE:
- STANDARD
- BORE SIZE IMPERIAL:
- STANDARD
- TYPE:
- CYLINDER HEAD
- PRODUCT NAME:
- GASKET
- THICKNESS METRIC:
- 1.14 MM
- UNITS:
- 2 PACK
MSRP: $97.95Now: $63.00Was: $97.95 -
On Sale
JAMES GASKET Cylinder Head Gasket ST-16500123
JAMES GASKET
MSRP: $97.95Now: $63.00Was: $97.95A compromised cylinder head gasket is one of the fastest ways to lose compression, coolant, and reliability on the track or street. The JAMES GASKET ST-16500123 is a genuine OEM-quality replacement that restores proper seal integrity and eliminates the...09346476- SKU:
- 09346476
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- RIDING STYLE:
- STREET
- MATERIAL:
- -
- THICKNESS IMPERIAL:
- 0,045'
- BORE SIZE:
- STANDARD
- PRODUCT NAME:
- GASKET
- THICKNESS METRIC:
- 1.14 MM
- TYPE:
- CYLINDER HEAD
- BORE SIZE IMPERIAL:
- STANDARD
- UNITS:
- 2 PACK
MSRP: $97.95Now: $63.00Was: $97.95Qty in Cart: 0Quantity:Price:MSRP: $97.95Now: $63.00Was: $97.95Subtotal: -
On Sale
JAMES GASKET Cam Chain Tensioner Gasket ST-25500005
JAMES GASKET
MSRP: $48.95Now: $31.00Was: $48.95A failing cam chain tensioner gasket will compromise your engine's internal sealing integrity and lead to costly oil leakage and potential timing chain wear. The JAMES GASKET ST-25500005 delivers a reliable, factory-quality replacement that restores...09346478- SKU:
- 09346478
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- 2 PACK
- TYPE:
- CAM CHAIN TENSIONER
- PRODUCT NAME:
- GASKET
- RIDING STYLE:
- STREET
MSRP: $48.95Now: $31.00Was: $48.95 -
On Sale
JAMES GASKET Water Pump Body Seal ST-26600017
JAMES GASKET
MSRP: $7.95Now: $5.00Was: $7.95A failing water pump seal is a silent engine killer—coolant leaks can lead to catastrophic overheating and thermal damage that sidelines your build or race season. The JAMES GASKET Water Pump Body Seal ST-26600017 delivers reliable, long-lasting sealing...09351085- SKU:
- 09351085
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- TYPE:
- WATER PUMP BODY
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SEAL
- UNITS:
- KIT
MSRP: $7.95Now: $5.00Was: $7.95 -
On Sale
JAMES GASKET Complete Motor Gasket Kit ST-25700443
JAMES GASKET
MSRP: $217.95Now: $139.00Was: $217.95A complete engine rebuild demands precision sealing across every critical junction—oil passages, combustion chambers, and bearing surfaces. This JAMES GASKET kit delivers OEM-quality gaskets, oil seals, and o-rings in one package, eliminating the...09346483- SKU:
- 09346483
- Availability:
- Ships Same Business Day
- Weight:
- 1.15 LBS
- BORE SIZE METRIC:
- 69.00 MM
- UNITS:
- KIT
- BORE SIZE:
- 69,00 MM
- RIDING STYLE:
- STREET
- THICKNESS IMPERIAL:
- 0.045'
- PRODUCT NAME:
- GASKET KIT
- TYPE:
- ENGINE
MSRP: $217.95Now: $139.00Was: $217.95 -
On Sale
JAMES GASKET Breather Baffle Gasket ST-29400074
JAMES GASKET
MSRP: $40.95Now: $26.00Was: $40.95A properly functioning breather system is critical to engine longevity and performance—excessive crankcase pressure leads to seal failure, oil leaks, and reduced reliability. The JAMES GASKET Breather Baffle Gasket ST-29400074 ensures a tight, dependable...09346485- SKU:
- 09346485
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- PRODUCT NAME:
- GASKET
- TYPE:
- BREATHER
- UNITS:
- 2 PACK
- RIDING STYLE:
- STREET
MSRP: $40.95Now: $26.00Was: $40.95 -
On Sale
JAMES GASKET Valve Cover - Grommet ST-6114-15
JAMES GASKET
MSRP: $19.95Now: $13.00Was: $19.95A properly sealed valve cover is critical to preventing oil leakage and maintaining clean engine bay conditions. The JAMES GASKET Valve Cover Grommet ST-6114-15 delivers reliable, long-lasting sealing performance with precision engineering and domestic...09346486- SKU:
- 09346486
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- PRODUCT NAME:
- GROMMET
- RIDING STYLE:
- STREET
- TYPE:
- VALVE COVER
- UNITS:
- 10 PACK
MSRP: $19.95Now: $13.00Was: $19.95 -
JE PISTONS Piston Kit 345192
JE PISTONS
$839.99When you're pushing your engine to the limits in professional competition, your pistons need to handle extreme pressures and temperatures without compromise. JE PISTONS 345192 kits are engineered specifically for forced induction and high-boost...09105946- SKU:
- 09105946
- Availability:
- Ships Same Business Day
- Weight:
- 2.91 LBS
- BORE SIZE METRIC:
- 80.00 MM
- PRODUCT NAME:
- PISTON KIT
- WALL THICKNESS:
- 0,160'
- DISPLACEMENT:
- 998 CC
- UNITS:
- KIT
- COMPRESSION RATIO IMPERIAL:
- 9.5:1
- PISTON HEAD SHAPE:
- DISHED
- RIDING STYLE:
- UTV
- WALL THICKNESS IMPERIAL:
- 0.160'
$839.99 -
JE PISTONS Piston Kit 208552
JE PISTONS
$309.99When you're pushing your engine to its absolute limit in professional competition, your pistons need to match that intensity. JE PISTONS' Pro Series 208552 kit delivers the precision engineering and structural reinforcement required for extreme...09105830- SKU:
- 09105830
- Availability:
- Ships Same Business Day
- Weight:
- 1.35 LBS
- BORE SIZE METRIC:
- 89.00 MM
- DISPLACEMENT:
- 435 CC
- PRODUCT NAME:
- PISTON KIT
- WALL THICKNESS IMPERIAL:
- 0.180'
- WALL THICKNESS:
- 0,180'
- COMPRESSION RATIO IMPERIAL:
- 12.0:1
- PISTON HEAD SHAPE:
- DOMED
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$309.99 -
JE PISTONS Piston Kit 128996
JE PISTONS
$269.99When you're pushing an engine to its absolute limit, stock pistons simply won't cut it. JE PISTONS' Pro Series 128996 kit is engineered specifically for professional competition and extreme applications, delivering the reliability and precision you need...09105832- SKU:
- 09105832
- Availability:
- Ships Same Business Day
- Weight:
- 1.50 LBS
- BORE - OVERSIZE:
- +4,00 MM
- PISTON HEAD SHAPE:
- FLAT TOP
- BORE - OVERSIZE METRIC:
- +4.00 MM
- BORE SIZE METRIC:
- 101.00 MM
- COMPRESSION RATIO IMPERIAL:
- 10.6:1
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- ROUND FORGED DESIGN
- UNITS:
- KIT
- DISPLACEMENT:
- 640 CC
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- PRODUCT NAME:
- PISTON KIT
- STYLE:
- JE PISTON
$269.99 -
JE PISTONS Piston Kit 128998
JE PISTONS
$269.99If you're pushing your engine to the limit in competition or high-performance applications, your pistons need to match that commitment. JE PISTONS' Pro Series 128998 kit delivers the precision engineering and durability required for extreme racing...09105833- SKU:
- 09105833
- Availability:
- Ships Same Business Day
- Weight:
- 1.55 LBS
- BORE - OVERSIZE:
- +5,00 MM
- BORE SIZE METRIC:
- 102.00 MM
- PRODUCT NAME:
- PISTON KIT
- DISPLACEMENT:
- 654 CC
- PISTON HEAD SHAPE:
- FLAT TOP
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- STYLE:
- JE PISTON
- COMPRESSION RATIO IMPERIAL:
- 10.8:1
- TYPE:
- ROUND FORGED DESIGN
- UNITS:
- KIT
- BORE - OVERSIZE METRIC:
- +5.00 MM
- RIDING STYLE:
- OFF-ROAD
$269.99 -
JE PISTONS Piston Kit 130682
JE PISTONS
$269.99When you're pushing your engine to the absolute limit in professional competition, your pistons need to handle extreme loads without compromise. JE PISTONS 130682 kits deliver the precision engineering and material science required for forced induction...09105834- SKU:
- 09105834
- Availability:
- Ships Same Business Day
- Weight:
- 1.61 LBS
- PISTON HEAD SHAPE:
- FLAT TOP
- TYPE:
- ROUND FORGED DESIGN
- BORE SIZE METRIC:
- 100.00 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE:
- STANDARD
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- PRODUCT NAME:
- PISTON KIT
- STYLE:
- JE PISTON
- BORE - OVERSIZE METRIC:
- STANDARD
- COMPRESSION RATIO IMPERIAL:
- 11.25:1
- DISPLACEMENT:
- 644 CC
$269.99 -
JE PISTONS Piston Kit 131243
JE PISTONS
$269.99When you're pushing an engine to its absolute limit in competition, your pistons need to match that intensity. JE's Pro Series kit delivers the precision engineering and durability required for extreme applications where failure isn't an option. Built...09105836- SKU:
- 09105836
- Availability:
- Ships Same Business Day
- Weight:
- 0.96 LBS
- COMPRESSION RATIO IMPERIAL:
- 10.5:1
- PISTON HEAD SHAPE:
- DOMED
- STYLE:
- JE PISTON
- TYPE:
- ROUND FORGED DESIGN
- UNITS:
- KIT
- DISPLACEMENT:
- 277 CC
- BORE - OVERSIZE:
- +4,00 MM
- BORE SIZE METRIC:
- 77.00 MM
- BORE - OVERSIZE METRIC:
- +4.00 MM
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- STREET
$269.99 -
JE PISTONS Piston Kit 133889
JE PISTONS
$269.99When you're pushing your engine to the limit in competition, your pistons need to withstand extreme pressures and temperatures without compromise. JE Pistons' Pro Series kit delivers the precision engineering and materials that separate winners from the...09105838- SKU:
- 09105838
- Availability:
- Ships Same Business Day
- Weight:
- 1.21 LBS
- BORE - OVERSIZE METRIC:
- +2.00 MM
- BORE SIZE METRIC:
- 87.00 MM
- DISPLACEMENT:
- 415 CC
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- JE PISTON
- UNITS:
- KIT
- BORE - OVERSIZE:
- +2,00 MM
- COMPRESSION RATIO IMPERIAL:
- 10.8:1
- PISTON HEAD SHAPE:
- DOMED
- TYPE:
- ROUND FORGED DESIGN
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- PRODUCT NAME:
- PISTON KIT
$269.99 -
JE PISTONS Piston Kit 177239
JE PISTONS
$269.99When you're pushing your engine to the limit in competition, every component needs to withstand extreme pressure and maintain precision under stress. JE Pistons' 177239 kit delivers the durability and performance you demand with forged 2618-T6 aluminum...09105840- SKU:
- 09105840
- Availability:
- Ships Same Business Day
- Weight:
- 1.16 LBS
- BORE - OVERSIZE:
- +3,00 MM
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- JE PISTON
- UNITS:
- KIT
- DISPLACEMENT:
- 426 CC
- PISTON HEAD SHAPE:
- DOMED
- TYPE:
- ROUND FORGED DESIGN
- BORE - OVERSIZE METRIC:
- +3.00 MM
- BORE SIZE METRIC:
- 88.00 MM
- COMPRESSION RATIO IMPERIAL:
- 13.0:1
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- PRODUCT NAME:
- PISTON KIT
$269.99 -
JE PISTONS Piston Kit 177240
JE PISTONS
$269.99When you're pushing your engine to the absolute limit in competition, your pistons need to survive extreme cylinder pressures and sustained high RPM without compromise. JE Pistons' Pro Series 177240 kit delivers the precision engineering and material...09105841- SKU:
- 09105841
- Availability:
- Ships Same Business Day
- Weight:
- 1.21 LBS
- BORE - OVERSIZE:
- +3,00 MM
- COMPRESSION RATIO IMPERIAL:
- 11.0:1
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- STYLE:
- JE PISTON
- DISPLACEMENT:
- 426 CC
- PISTON HEAD SHAPE:
- DOMED
- TYPE:
- ROUND FORGED DESIGN
- UNITS:
- KIT
- BORE - OVERSIZE METRIC:
- +3.00 MM
- BORE SIZE METRIC:
- 88.00 MM
- PRODUCT NAME:
- PISTON KIT
$269.99Qty in Cart: 0Quantity:Price:$269.99Subtotal: -
JE PISTONS Piston Kit 180297
JE PISTONS
$269.99When you're pushing your engine to its absolute limits, your pistons need to withstand extreme pressures and temperatures without compromise. JE PISTONS' Pro Series 180297 kit is engineered specifically for professional competition and high-boost...09105842- SKU:
- 09105842
- Availability:
- Ships Same Business Day
- Weight:
- 1.16 LBS
- BORE - OVERSIZE:
- STANDARD
- DISPLACEMENT:
- 398 CC
- RIDING STYLE:
- ATV
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- STYLE:
- JE PISTON
- BORE - OVERSIZE METRIC:
- STANDARD
- COMPRESSION RATIO IMPERIAL:
- 12.0:1
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- ROUND FORGED DESIGN
- UNITS:
- KIT
- BORE SIZE METRIC:
- 90.00 MM
- PISTON HEAD SHAPE:
- DISHED
- PRODUCT NAME:
- PISTON KIT
$269.99 -
JE PISTONS Piston Kit 183051
JE PISTONS
$269.99When you're pushing your engine to the absolute limit in competition, your pistons need to handle extreme pressures and temperatures without compromise. JE PISTONS' Pro Series kit delivers the precision engineering and durability required for...09105843- SKU:
- 09105843
- Availability:
- Ships Same Business Day
- Weight:
- 1.41 LBS
- BORE SIZE METRIC:
- 94.00 MM
- COMPRESSION RATIO IMPERIAL:
- 12.0:1
- RIDING STYLE:
- ATV
- BORE - OVERSIZE METRIC:
- +4.00 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- PRODUCT NAME:
- PISTON KIT
- STYLE:
- JE PISTON
- BORE - OVERSIZE:
- +4,00 MM
- DISPLACEMENT:
- 434 CC
- PISTON HEAD SHAPE:
- DISHED
- TYPE:
- ROUND FORGED DESIGN
$269.99 -
JE PISTONS Piston Kit 209283
JE PISTONS
$309.99When you're pushing your engine to its absolute limit in competition, your pistons need to survive extreme pressure, heat, and detonation without compromise. JE PISTONS Pro Series delivers the precision engineering and material science required for...09105844- SKU:
- 09105844
- Availability:
- Ships Same Business Day
- Weight:
- 1.41 LBS
- WALL THICKNESS:
- 0,150'
- BORE SIZE METRIC:
- 100.00 MM
- DISPLACEMENT:
- 651 CC
- UNITS:
- KIT
- COMPRESSION RATIO IMPERIAL:
- 11.5:1
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- ATV
- PISTON HEAD SHAPE:
- DOMED
- WALL THICKNESS IMPERIAL:
- 0.150'
$309.99
