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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COMETIC Gasket Set - 95 mm - Yamaha C7908-EST
COMETIC
$89.95A quality gasket set is non-negotiable when you're rebuilding a top end—it's the seal between raw power and catastrophic failure. The COMETIC C7908-EST delivers the sealing reliability you need for high-output 4-stroke engines, whether naturally...09340933- SKU:
- 09340933
- Availability:
- Ships Same Business Day
- Weight:
- 0.23 LBS
- BORE SIZE METRIC:
- 95.00 MM
- UNITS:
- KIT
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- STREET
- TYPE:
- TOP END
$89.95Qty in Cart: 0Quantity:Price:$89.95Subtotal: -
COMETIC Gasket Set - 77 mm - Yamaha C7905-EST
COMETIC
$83.95High-output 4-stroke engines demand gasket solutions engineered for extreme cylinder pressures and heat cycles. The COMETIC C7905-EST Gasket Set delivers reliable sealing across naturally aspirated and forced-induction applications, preventing blowby and...09340932- SKU:
- 09340932
- Availability:
- Ships Same Business Day
- Weight:
- 0.19 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- KIT
- BORE SIZE METRIC:
- 77.00 MM
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- GASKET KIT
$83.95 -
COMETIC Gasket Set - 78 mm - Honda C3133-EST
COMETIC
$84.95Factory gaskets can't handle the cylinder pressures generated by high-output 4-stroke engines, whether naturally aspirated or boosted. The COMETIC C3133-EST gasket set uses multi-layered steel construction with Extreme Sealing Technology (EST) to...09340920- SKU:
- 09340920
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- TYPE:
- TOP END
- BORE SIZE METRIC:
- 78.00 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- GASKET KIT
$84.95 -
COMETIC Gasket Set - 96 mm - Honda C3047-EST
COMETIC
$88.95When running high-output forced induction or naturally aspirated builds, your factory gasket set becomes a liability. The COMETIC C3047-EST Gasket Set uses advanced multi-layered steel construction with EST (Extreme Sealing Technology) to handle extreme...09340905- SKU:
- 09340905
- Availability:
- Ships Same Business Day
- Weight:
- 0.17 LBS
- TYPE:
- TOP END
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- GASKET KIT
- BORE SIZE METRIC:
- 96.00 MM
$88.95Qty in Cart: 0Quantity:Price:$88.95Subtotal: -
On Sale
ATHENA Cylinder Gasket Kit - Yamaha 070203/1
ATHENA
MSRP: $14.95Now: $13.00Was: $14.95When you've committed to a 70cc big bore conversion on your Yamaha, a compromised cylinder gasket is a silent performance killer—leaking compression, oil, and coolant before you even notice. The ATHENA Cylinder Gasket Kit 070203/1 is engineered...09340639- SKU:
- 09340639
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- RIDING STYLE:
- STREET
- TYPE:
- TOP END
- PRODUCT NAME:
- GASKET KIT
- UNITS:
- KIT
MSRP: $14.95Now: $13.00Was: $14.95 -
On Sale
ATHENA Cylinder Gasket Kit - Yamaha 070103/1
ATHENA
MSRP: $14.95Now: $13.00Was: $14.95When you've upgraded to an Athena 70cc big bore kit, maintaining a reliable seal between your cylinder and head is critical to preserving compression and preventing coolant or oil leakage. This OEM-equivalent gasket kit ensures a proper fit and long-term...09340638- SKU:
- 09340638
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- GASKET KIT
- TYPE:
- TOP END
- UNITS:
- KIT
MSRP: $14.95Now: $13.00Was: $14.95 -
COMETIC Top End Gasket Kit C7181
COMETIC
$51.95A quality gasket kit is the foundation of a reliable top end—poor sealing leads to compression loss, oil leakage, and catastrophic engine failure. The COMETIC C7181 uses multi-layered steel construction with Viton rubber coating to handle extreme...09340315- SKU:
- 09340315
- Availability:
- Ships Same Business Day
- Weight:
- 0.09 LBS
- THICKNESS IMPERIAL:
- 0,012'
- TYPE:
- TOP END
- BORE SIZE METRIC:
- 54.00 MM
- THICKNESS METRIC:
- 0.31 MM
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$51.95 -
WINDEROSA Top End Gasket Kit - SL/SLTX1100 610806
WINDEROSA
$67.05Top-end gasket failure leads to compression loss, oil leaks, and catastrophic engine damage—replacing them preventatively with a complete OEM-quality kit saves you thousands in rebuild costs. The WINDEROSA Top End Gasket Kit gives you all the critical...09340271- SKU:
- 09340271
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- WATERCRAFT
- TYPE:
- TOP END
- UNITS:
- KIT
$67.05 -
On Sale
ATHENA Gasket - KLX/DRZ/KFX/LTZ400 P400510160002
ATHENA
MSRP: $133.95Now: $121.00Was: $133.95Stock gaskets wear down under sustained performance use, leading to coolant leaks and compromised sealing integrity that can damage your engine. The ATHENA Gasket Kit is engineered specifically for KLX, DRZ, KFX, and LTZ400 platforms to deliver reliable...09340194- SKU:
- 09340194
- Availability:
- Ships Same Business Day
- Weight:
- 0.18 LBS
- TYPE:
- TOP END
- UNITS:
- KIT
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- BORE SIZE:
- 94,00 MM
- RIDING STYLE:
- STREET
- BORE SIZE METRIC:
- 94.00 MM
- DISPLACEMENT:
- 435 CC
- RIDING STYLE:
- OFF-ROAD
MSRP: $133.95Now: $121.00Was: $133.95 -
On Sale
ATHENA Cylinder Gasket Kit - KX125 P400250160001
ATHENA
MSRP: $57.95Now: $52.00Was: $57.95Maintain peak performance and reliability with the ATHENA Cylinder Gasket Kit, engineered to restore your KX125 to factory specifications or exceed them with premium materials. The nickel-carbide coated aluminum cylinder and molybdenum-coated forged...09340190- SKU:
- 09340190
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE:
- 54,00 MM
- BORE SIZE METRIC:
- 54.00 MM
- TYPE:
- TOP END
MSRP: $57.95Now: $52.00Was: $57.95 -
Cylinder Works Standard Bore High Compression Cylinder Kit for Polaris RZR 900 2015-2016 60004-K01HC
CYLINDER WORKS
$1,353.95If you're running a Polaris RZR 900 and want to restore original performance or eliminate the guesswork of piston-to-cylinder matching, this bolt-on kit delivers exactly what you need. The included Vertex pistons are precision-matched to the cylinder,...09310735- SKU:
- 09310735
- Availability:
- Ships Same Business Day
- Weight:
- 9.85 LBS
- UNITS:
- KIT
- BORE SIZE METRIC:
- 93.00 MM
- COMPRESSION RATIO IMPERIAL:
- 11.5:1
- CYLINDER DIAMETER:
- 93,00 MM
- ENGINE TYPE:
- 4-CYCLE
- PRODUCT NAME:
- CYLINDER KIT
- CYLINDER DIAMETER METRIC:
- 93.00 MM
- RIDING STYLE:
- UTV
- STYLE:
- STANDARD
$1,353.95 -
Cylinder Works Cylinder Kit Standard 40004-K02
CYLINDER WORKS
$704.95If you're running a two-stroke engine that's seen significant mileage, a worn cylinder directly kills performance—reducing compression, increasing blow-by, and forcing you to compensate with richer jetting just to maintain baseline power. The Cylinder...09310502- SKU:
- 09310502
- Availability:
- Ships Same Business Day
- Weight:
- 3.30 LBS
- COMPRESSION RATIO IMPERIAL:
- 13.5:1
- CYLINDER DIAMETER METRIC:
- 77.00 MM
- DISPLACEMENT:
- 249 CC
- ENGINE TYPE:
- 4-CYCLE
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- STYLE:
- STANDARD
- CYLINDER DIAMETER:
- 77,00 MM
- PRODUCT NAME:
- CYLINDER KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$704.95 -
Cylinder Works Big Bore Cylinder Kit for Suzuki RM-Z250 2013-2018 41004-K02
CYLINDER WORKS
$799.95If you're running a 2013-2018 RM-Z250, a big bore cylinder kit is one of the most cost-effective ways to unlock measurable gains in displacement and power without a complete engine rebuild. The Cylinder Works Big Bore Kit delivers bolt-on simplicity...09310501- SKU:
- 09310501
- Availability:
- Ships Same Business Day
- Weight:
- 3.20 LBS
- COMPRESSION RATIO IMPERIAL:
- 13.5:1
- ENGINE TYPE:
- 4-CYCLE
- PRODUCT NAME:
- CYLINDER KIT
- STYLE:
- BIG BORE
- CYLINDER DIAMETER METRIC:
- 80.00 MM
- RIDING STYLE:
- OFF-ROAD
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- CYLINDER DIAMETER:
- 80,00 MM
- DISPLACEMENT:
- 269 CC
- OVERBORE METRIC:
- +3.00 MM
- UNITS:
- KIT
$799.95 -
Cylinder Works Standard Bore Cylinder Kit KTM 65 SX 2009-2023 50005-K01
CYLINDER WORKS
$788.95When your KTM 65 SX starts showing signs of wear, a proper cylinder refresh is the most cost-effective way to restore lost compression and power. The Cylinder Works Standard Bore Kit eliminates guesswork by pairing a precision-machined cylinder with...09310500- SKU:
- 09310500
- Availability:
- Ships Same Business Day
- Weight:
- 2.85 LBS
- COMPRESSION RATIO IMPERIAL:
- 2.09:1
- PRODUCT NAME:
- CYLINDER KIT
- CYLINDER DIAMETER:
- 45,00 MM
- CYLINDER DIAMETER METRIC:
- 45.00 MM
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- ENGINE TYPE:
- 2-CYCLE
- UNITS:
- KIT
- DISPLACEMENT:
- 65 CC
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- STANDARD
$788.95 -
Cylinder Works Standard Bore Cylinder Kit 2013-2015 KTM 350 SX-F 350 XC-F 50003-K01
CYLINDER WORKS
$867.95When your KTM 350 SX-F or XC-F's cylinder wears beyond acceptable limits, a quality replacement isn't optional—it's essential to maintaining peak compression, throttle response, and engine longevity. The Cylinder Works Standard Bore Kit delivers...09310497- SKU:
- 09310497
- Availability:
- Ships Same Business Day
- Weight:
- 3.85 LBS
- COMPRESSION RATIO IMPERIAL:
- 13.6:1
- CYLINDER DIAMETER:
- 88,00 MM
- ENGINE TYPE:
- 4-CYCLE
- STYLE:
- STANDARD
- CYLINDER DIAMETER METRIC:
- 88.00 MM
- DISPLACEMENT:
- 350 CC
- RIDING STYLE:
- OFF-ROAD
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- PRODUCT NAME:
- CYLINDER KIT
- UNITS:
- KIT
$867.95Qty in Cart: 0Quantity:Price:$867.95Subtotal: -
Cylinder Works Big Bore Cylinder Kit for 2013-2015 KTM 350 SX-F 35003-K01
CYLINDER WORKS
$982.95If you're running a 2013-2015 KTM 350 SX-F, this big bore kit delivers measurable gains in displacement and power without requiring extensive machine work or re-plating. The bolt-on design means you'll be back on the track or trail quickly, while the...09310495- SKU:
- 09310495
- Availability:
- Ships Same Business Day
- Weight:
- 3.70 LBS
- ENGINE TYPE:
- 4-CYCLE
- CYLINDER DIAMETER METRIC:
- 90.00 MM
- COMPRESSION RATIO IMPERIAL:
- 13.5:1
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- CYLINDER DIAMETER:
- 90,00 MM
- DISPLACEMENT:
- 365 CC
- OVERBORE METRIC:
- +2.00 MM
- PRODUCT NAME:
- CYLINDER KIT
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- BIG BORE
- UNITS:
- KIT
$982.95 -
Cylinder Works Yamaha YZ 450 F 2010-2013 High Compression Cylinder Kit 21005-K01
CYLINDER WORKS
$901.95Stock YZ 450F cylinders sacrifice durability and peak performance for cost savings. The Cylinder Works High Compression Kit restores the power and reliability your engine demands, delivering measurable gains in combustion efficiency and ring seal without...09310354- SKU:
- 09310354
- Availability:
- Ships Same Business Day
- Weight:
- 4.45 LBS
- CYLINDER DIAMETER METRIC:
- 99.00 MM
- RIDING STYLE:
- OFF-ROAD
- DISPLACEMENT:
- 468 CC
- STYLE:
- HIGH COMPRESSION
- COMPRESSION RATIO IMPERIAL:
- 12.5:1
- CYLINDER DIAMETER:
- 99,00 MM
- ENGINE TYPE:
- 4-CYCLE
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- PRODUCT NAME:
- CYLINDER KIT
- UNITS:
- KIT
$901.95 -
Cylinder Works Standard Bore Cylinder Kit 77mm 13.4:1 Compression Suzuki RM-Z250 2007-2009 40003-K01
CYLINDER WORKS
$704.95If you're running a 2007-2009 RM-Z250 and want genuine performance gains without the headache of machine work, this Cylinder Works kit delivers a straightforward path to increased displacement and compression. The 77mm bore paired with a 13.4:1...09310352- SKU:
- 09310352
- Availability:
- Ships Same Business Day
- Weight:
- 3.20 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- CYLINDER DIAMETER:
- 77,00 MM
- DISPLACEMENT:
- 249 CC
- ENGINE TYPE:
- 4-CYCLE
- PRODUCT NAME:
- CYLINDER KIT
- CYLINDER DIAMETER METRIC:
- 77.00 MM
- STYLE:
- STANDARD
- COMPRESSION RATIO IMPERIAL:
- 13.4:1
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
$704.95Qty in Cart: 0Quantity:Price:$704.95Subtotal: -
Cylinder Works Standard Bore Cylinder Kit 2010-2013 Yamaha YZ450F 20005-K01
CYLINDER WORKS
$804.95If you're running a 2010-2013 YZ450F, a worn or damaged cylinder directly impacts combustion efficiency, power delivery, and engine longevity. The Cylinder Works Standard Bore Kit restores your engine to factory specifications—or better—with matched...09310345- SKU:
- 09310345
- Availability:
- Ships Same Business Day
- Weight:
- 4.58 LBS
- CYLINDER DIAMETER:
- 97,00 MM
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
- STYLE:
- STANDARD
- COMPRESSION RATIO IMPERIAL:
- 12.5:1
- CYLINDER DIAMETER METRIC:
- 97.00 MM
- ENGINE TYPE:
- 4-CYCLE
- DISPLACEMENT:
- 449 CC
- PRODUCT NAME:
- CYLINDER KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$804.95 -
Cylinder Works Kawasaki KX250F 2010 Standard Bore Cylinder Kit 77mm 13.2:1 30005-K01
CYLINDER WORKS
$679.95Factory cylinder wear limits piston-to-wall clearance and reduces combustion efficiency—a complete cylinder kit restores your KX250F's compression, throttle response, and ring seal integrity. The Cylinder Works standard bore design delivers proven...09310341- SKU:
- 09310341
- Availability:
- Ships Same Business Day
- Weight:
- 3.30 LBS
- COMPRESSION RATIO IMPERIAL:
- 13.2:1
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- CYLINDER DIAMETER:
- 77,00 MM
- DISPLACEMENT:
- 249 CC
- ENGINE TYPE:
- 4-CYCLE
- PRODUCT NAME:
- CYLINDER
- CYLINDER DIAMETER METRIC:
- 77.00 MM
- STYLE:
- STANDARD
- CYLINDER BORE COATING:
- NICKEL-SILICON CARBIDE
$679.95
