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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VERTEX Top End Gasket Kit - Kawasaki 810483
VERTEX
$31.33A top-end gasket kit is essential for maintaining a proper seal between critical engine components, preventing coolant and oil leaks that compromise engine reliability and performance. Whether you're rebuilding after high-mileage wear or preparing for...09348033- SKU:
- 09348033
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
$31.33 -
VERTEX Top End Gasket Kit - KTM 810315
VERTEX
$26.38A failed top-end gasket can cost you race time and engine reliability. The VERTEX Top End Gasket Kit (810315) delivers OEM-quality sealing with precision-cut components engineered to handle the heat and pressure of demanding riding conditions. Whether...09348019- SKU:
- 09348019
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
$26.38 -
VERTEX Top End Gasket Kit - Honda 810235
VERTEX
$38.13A compromised top-end gasket can silently rob your Honda engine of power, efficiency, and reliability—especially under high-load conditions. The VERTEX 810235 Top End Gasket Kit delivers complete sealing integrity with precision-engineered components...09348016- SKU:
- 09348016
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
$38.13 -
VINTCO Crankshaft Assembly - Yamaha CR2027
VINTCO
$419.95A crankshaft is the backbone of your engine's bottom end—it converts combustion energy into rotational power, and any weakness here cascades through your entire drivetrain. The VINTCO CR2027 pairs a robust forged steel construction with a...09210950- SKU:
- 09210950
- Availability:
- Ships Same Business Day
- Weight:
- 10.20 LBS
$419.95 -
BOYESEN Water Pump Kit - Black - Gas Gas/Husqvarna/KTM WPK-42B
BOYESEN
$194.95A reliable water pump is critical to maintaining optimal engine temperatures under sustained high-RPM operation, especially in closed-loop cooling systems found on modern off-road machines. The BOYESEN Water Pump Kit delivers OEM-equivalent performance...09320308- SKU:
- 09320308
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
$194.95 -
JE PISTONS Piston Kit - 13.5:1 - Kawasaki 379938
JE PISTONS
$346.99If you're running your Kawasaki engine at the edge of competition, your stock pistons won't survive—you need forged internals engineered for extreme duty. JE's 13.5:1 compression pistons deliver the strength and precision required for professional racing...09106679- SKU:
- 09106679
- Availability:
- Ships Same Business Day
- Weight:
- 1.07 LBS
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- COMPRESSION RATIO IMPERIAL:
- 13.5:1
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
$346.99 -
JE PISTONS Piston Kit - 14.5:1 - Kawasaki 391920
JE PISTONS
$316.99If you're running a high-compression build or pushing your Kawasaki engine into professional competition territory, you need pistons engineered for the abuse. JE's 14.5:1 compression kit delivers the strength and precision required to survive extreme...09106680- SKU:
- 09106680
- Availability:
- Ships Same Business Day
- Weight:
- 0.78 LBS
- PISTON MATERIAL:
- FORGED 2618 ALUMINUM
- RIDING STYLE:
- OFF-ROAD
- COMPRESSION RATIO IMPERIAL:
- 14.5:1
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
$316.99 -
On Sale
ATHENA Piston Kit with Gaskets - 95.97 mm - KX450F P5F0960072007A
ATHENA
MSRP: $263.07Now: $237.00Was: $263.07Stock pistons wear, lose compression, and rob you of the responsiveness your KX450F demands on technical terrain. This ATHENA piston kit restores full performance potential while engineering in durability for repeat heat cycles—ideal if you're running...09031750- SKU:
- 09031750
- Availability:
- Ships Same Business Day
- Weight:
- 1.55 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE METRIC:
- 95.97 MM
- DISPLACEMENT:
- 450 CC
- TYPE:
- TOP END
- COMPRESSION RATIO IMPERIAL:
- 12.5:1
- MODEL:
- A
- PRODUCT NAME:
- PISTON KIT
MSRP: $263.07Now: $237.00Was: $263.07 -
On Sale
ATHENA Piston Kit with Gaskets - 95.95 mm - CRF450R P5F0960322006A
ATHENA
MSRP: $259.07Now: $233.00Was: $259.07A worn or stock piston limits your CRF450R's combustion efficiency and reliability—especially under sustained high-RPM riding or aggressive trail conditions. The ATHENA Piston Kit delivers precision-engineered performance with CNC-machined construction...09031744- SKU:
- 09031744
- Availability:
- Ships Same Business Day
- Weight:
- 1.53 LBS
- BORE SIZE METRIC:
- 95.95 MM
- DISPLACEMENT:
- 450 CC
- PRODUCT NAME:
- PISTON KIT
- COMPRESSION RATIO IMPERIAL:
- 13.5:1
- PISTON MATERIAL:
- FORGED
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- MODEL:
- A
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
MSRP: $259.07Now: $233.00Was: $259.07 -
On Sale
ATHENA Piston Kit with Gaskets - 95.95 mm - CRF450R P5F0960320006A
ATHENA
MSRP: $261.07Now: $235.00Was: $261.07When your CRF450R's piston shows wear, combustion efficiency drops and power delivery suffers—this ATHENA piston kit restores that performance with precision-engineered components built to OEM specifications. The high-performance aluminum alloy...09031746- SKU:
- 09031746
- Availability:
- Ships Same Business Day
- Weight:
- 1.53 LBS
- BORE SIZE METRIC:
- 95.95 MM
- PRODUCT NAME:
- PISTON KIT
- COMPRESSION RATIO IMPERIAL:
- 13.5:1
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- MODEL:
- A
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- DISPLACEMENT:
- 450 CC
- TYPE:
- TOP END
MSRP: $261.07Now: $235.00Was: $261.07 -
On Sale
ATHENA Piston Kit with Gaskets - 95.96 mm - CRF450R P5F0960320006B
ATHENA
MSRP: $261.07Now: $235.00Was: $261.07A worn or damaged piston directly compromises combustion efficiency, power output, and engine longevity—especially in high-demand off-road riding. The ATHENA 95.96 mm Piston Kit restores your CRF450R to factory specifications with OEM-quality materials...09031747- SKU:
- 09031747
- Availability:
- Ships Same Business Day
- Weight:
- 1.50 LBS
- COMPRESSION RATIO IMPERIAL:
- 13.5:1
- PISTON MATERIAL:
- FORGED
- BORE SIZE METRIC:
- 95.96 MM
- DISPLACEMENT:
- 450 CC
- MODEL:
- B
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
MSRP: $261.07Now: $235.00Was: $261.07 -
On Sale
ATHENA Piston Kit with Gaskets - 95.97 mm - KX450F P5F0960068007A
ATHENA
MSRP: $265.02Now: $239.00Was: $265.02When you're pushing a KX450F to its limits, a worn or stock piston becomes your bottleneck—restricting flow, sapping power, and threatening reliability under sustained load. The ATHENA Piston Kit delivers a precision-engineered replacement that restores...09031752- SKU:
- 09031752
- Availability:
- Ships Same Business Day
- Weight:
- 1.50 LBS
- COMPRESSION RATIO IMPERIAL:
- 12.5:1
- ENGINE TYPE:
- 4-STROKE
- MODEL:
- A
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- DISPLACEMENT:
- 450 CC
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 95.97 MM
- TYPE:
- TOP END
MSRP: $265.02Now: $239.00Was: $265.02 -
On Sale
ATHENA Piston Kit with Gaskets - 95.98 mm - KX450F P5F0960068007B
ATHENA
MSRP: $265.02Now: $239.00Was: $265.02A worn or damaged piston directly kills your engine's compression, throttle response, and overall reliability—especially critical in high-demand 4-stroke off-road applications. The ATHENA Piston Kit delivers precision-engineered internals that restore...09031753- SKU:
- 09031753
- Availability:
- Ships Same Business Day
- Weight:
- 1.51 LBS
- COMPRESSION RATIO IMPERIAL:
- 12.5:1
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- DISPLACEMENT:
- 450 CC
- TYPE:
- TOP END
- MODEL:
- B
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 95.98 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
MSRP: $265.02Now: $239.00Was: $265.02 -
On Sale
ATHENA Piston Kit with Gaskets - 95.95 mm - KX450F P5F0960066002A
ATHENA
MSRP: $273.07Now: $246.00Was: $273.07When your KX450F is pushing peak RPMs on the track or trail, a worn piston compromises compression, power delivery, and engine longevity. The ATHENA Piston Kit delivers OE-equivalent reliability with enhanced durability—engineered for riders who demand...09031754- SKU:
- 09031754
- Availability:
- Ships Same Business Day
- Weight:
- 1.60 LBS
- COMPRESSION RATIO IMPERIAL:
- 12.5:1
- MODEL:
- A
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- BORE SIZE METRIC:
- 95.95 MM
- PRODUCT NAME:
- PISTON KIT
- DISPLACEMENT:
- 450 CC
- TYPE:
- TOP END
MSRP: $273.07Now: $246.00Was: $273.07 -
On Sale
ATHENA Piston Kit with Gaskets - 94.95 mm - SXF450 P5F0950081002A
ATHENA
MSRP: $279.95Now: $252.00Was: $279.95When you're pushing your SXF450 to its limits, your piston needs to deliver reliability under extreme heat and pressure. The ATHENA Piston Kit combines OE-equivalent durability with enhanced material strength, giving you the performance gains you're...09031756- SKU:
- 09031756
- Availability:
- Ships Same Business Day
- Weight:
- 1.54 LBS
- BORE SIZE METRIC:
- 94.95 MM
- TYPE:
- TOP END
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- MODEL:
- A
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- COMPRESSION RATIO IMPERIAL:
- 12.8:1
- PISTON MATERIAL:
- FORGED
- DISPLACEMENT:
- 449 CC
- RIDING STYLE:
- OFF-ROAD
MSRP: $279.95Now: $252.00Was: $279.95 -
On Sale
ATHENA Piston Kit with Gaskets - 87.96 mm - SXF350 P5F0880079001B
ATHENA
MSRP: $311.02Now: $280.00Was: $311.02A worn or damaged piston directly compromises combustion efficiency, throttle response, and engine longevity—particularly critical in 4-stroke off-road applications where reliability matters. The ATHENA Piston Kit delivers precision-engineered...09031763- SKU:
- 09031763
- Availability:
- Ships Same Business Day
- Weight:
- 1.39 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- STREET
- COMPRESSION RATIO IMPERIAL:
- 14.2:1
- DISPLACEMENT:
- 349 CC
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- BORE SIZE METRIC:
- 87.96 MM
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
- UNITS:
- KIT
- MODEL:
- B
MSRP: $311.02Now: $280.00Was: $311.02 -
On Sale
ATHENA Piston Kit with Gaskets - 96.95 mm - YZ450F P5F0970197004A
ATHENA
MSRP: $242.15Now: $218.00Was: $242.15When your YZ450F's piston is nearing the end of its service life, installing OEM-equivalent replacement parts is critical to maintaining reliability and power delivery. This ATHENA piston kit delivers the durability and performance characteristics of...09031768- SKU:
- 09031768
- Availability:
- Ships Same Business Day
- Weight:
- 1.55 LBS
- TYPE:
- TOP END
- BORE SIZE METRIC:
- 96.95 MM
- ENGINE TYPE:
- 4-STROKE
- MODEL:
- A
- PRODUCT NAME:
- PISTON KIT
- COMPRESSION RATIO IMPERIAL:
- 12.8:1
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON MATERIAL:
- FORGED
- DISPLACEMENT:
- 450 CC
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $242.15Now: $218.00Was: $242.15 -
Cylinder Works Big Bore Cylinder Kit 295cc for Yamaha YZ250 1999-2023 21009-K01
CYLINDER WORKS
$1,195.95The Cylinder Works Big Bore Kit transforms your YZ250 into a more potent machine by increasing displacement to 295cc—delivering measurable gains in mid-range and peak power without sacrificing the reliability you depend on for consistent track...09311163- SKU:
- 09311163
- Availability:
- Ships Same Business Day
- Weight:
- 8.71 LBS
- COLOR/FINISH:
- GRAY
- CYLINDER DIAMETER:
- 72,00 MM
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- CYLINDER DIAMETER METRIC:
- 72.00 MM
- DISPLACEMENT:
- 295 CC
- OVERBORE METRIC:
- +5.60 MM
- PRODUCT NAME:
- CYLINDER KIT
- STYLE:
- BIG BORE
$1,195.95 -
ACERBIS X-Power Kit - Black - Suzuki 2983330001
ACERBIS
$76.95Crankcase damage from crashes or overheating can sideline your bike and drain your wallet. The ACERBIS X-Power Kit provides comprehensive protection for both your clutch and ignition crankcases while managing heat through strategically designed air...09402143- SKU:
- 09402143
- Availability:
- Ships Same Business Day
- Weight:
- 1.47 LBS
- COLOR/FINISH:
- BLACK
- MATERIAL:
- METAL
- MATERIAL:
- PLASTIC
- RIDING STYLE:
- STREET
- MODEL:
- X-POWER
- TYPE:
- SIDE COVER
- PRODUCT NAME:
- X-POWER KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$76.95 -
ACERBIS X-Power Kit - Black - Husqvarna/KTM 2983230001
ACERBIS
$76.95Off-road riding exposes your engine to constant threats—mud, debris, sand, and extreme heat that can compromise critical components. The ACERBIS X-Power Kit delivers comprehensive protection for your Husqvarna or KTM's clutch cover, water pump, lower...09402144- SKU:
- 09402144
- Availability:
- Ships Same Business Day
- Weight:
- 1.45 LBS
- MODEL:
- X-POWER
- COLOR/FINISH:
- BLACK
- MATERIAL:
- PLASTIC
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- MATERIAL:
- STEEL
- PRODUCT NAME:
- X-POWER KIT
- TYPE:
- SIDE COVER
$76.95
