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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PROX Piston Kit 01.2225.C
PROX
$121.95When your engine is running at the limit, piston reliability becomes non-negotiable. The PROX Piston Kit 01.2225.C delivers OEM-quality replacement pistons engineered to withstand high-RPM demands without compromise. This complete kit eliminates the...09100596- SKU:
- 09100596
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- BORE SIZE METRIC:
- 53.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 53.97 MM
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
$121.95 -
PROX Piston Kit 01.1225.A
PROX
$105.95A piston kit is the heart of your engine's combustion cycle, and worn or damaged pistons directly compromise compression, power delivery, and reliability. The PROX Piston Kit 01.1225.A delivers OEM-spec performance with Japanese engineering precision,...09100597- SKU:
- 09100597
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.94 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON DIAMETER METRIC:
- 53.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
$105.95Qty in Cart: 0Quantity:Price:$105.95Subtotal: -
PROX Piston Kit 01.1225.B
PROX
$105.95If your engine is showing signs of wear—excessive blow-by, loss of compression, or visible scoring on the cylinder walls—a worn piston kit is the direct path back to reliable performance and proper sealing. The PROX Piston Kit 01.1225.B delivers...09100598- SKU:
- 09100598
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.95 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
$105.95Qty in Cart: 0Quantity:Price:$105.95Subtotal: -
PROX Piston Kit 01.1225.C
PROX
$105.95Whether you're rebuilding a tired engine or replacing worn components after high-mileage use, the PROX Piston Kit 01.1225.C delivers OEM-spec reliability with precision engineering that ensures consistent performance and longevity. Cast from...09100599- SKU:
- 09100599
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- PISTON DIAMETER METRIC:
- 53.96 MM
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- PRODUCT NAME:
- PISTON KIT
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
$105.95Qty in Cart: 0Quantity:Price:$105.95Subtotal: -
PROX Piston Kit 01.4325.B
PROX
$139.95When your engine's pistons show wear or damage, you're facing power loss, compression issues, and potential catastrophic failure. The PROX Piston Kit 01.4325.B delivers OEM-quality replacement pistons engineered to restore your engine's original...09100600- SKU:
- 09100600
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.35 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON DIAMETER METRIC:
- 66.35 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Kit 01.1414.B
PROX
$210.95A piston kit is fundamental to engine reliability and performance—wear or damage compromises compression, efficiency, and power delivery. The PROX Piston Kit 01.1414.B delivers OEM-grade quality with precision engineering, ensuring your engine maintains...09100608- SKU:
- 09100608
- Availability:
- Ships Same Business Day
- Weight:
- 0.82 LBS
- PISTON DIAMETER METRIC:
- 95.97 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$210.95 -
PROX Piston Kit 01.1075.000
PROX
$77.95A piston kit is the heart of your engine's combustion cycle—when yours are worn, scored, or damaged, you lose compression, power, and reliability. The PROX Piston Kit 01.1075.000 restores your engine to OEM-specification performance with...09100399- SKU:
- 09100399
- Availability:
- Ships Same Business Day
- Weight:
- 0.19 LBS
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 47.00 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 47.00 MM
$77.95 -
PROX Piston Kit 01.1075.050
PROX
$77.95When your engine demands precision and reliability, OEM-equivalent pistons are non-negotiable. The PROX Piston Kit 01.1075.050 delivers factory-spec performance with Japanese manufacturing precision, ensuring consistent combustion chamber geometry and...09100400- SKU:
- 09100400
- Availability:
- Ships Same Business Day
- Weight:
- 0.27 LBS
- PISTON DIAMETER METRIC:
- 47.50 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE IMPERIAL:
- +0.020'
- BORE SIZE METRIC:
- 47.50 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$77.95 -
PROX Piston Kit 01.1075.100
PROX
$59.95Worn or damaged pistons compromise engine efficiency, reduce horsepower, and accelerate wear on surrounding components. The PROX Piston Kit 01.1075.100 delivers OEM-equivalent performance with precision manufacturing, restoring your engine to factory...09100401- SKU:
- 09100401
- Availability:
- Ships Same Business Day
- Weight:
- 0.27 LBS
- BORE SIZE METRIC:
- 48.00 MM
- PRODUCT NAME:
- PISTON KIT
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 48.00 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE IMPERIAL:
- +0.040'
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$59.95 -
PROX Piston Kit 01.1403.A
PROX
$195.95Your engine's pistons are the workhorses converting combustion into power—wear them out, and you lose compression, efficiency, and reliability. The PROX Piston Kit 01.1403.A delivers OEM-equivalent performance with precision manufacturing and premium...09100418- SKU:
- 09100418
- Availability:
- Ships Same Business Day
- Weight:
- 0.56 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 95.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- BORE SIZE METRIC:
- 95.96 MM
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$195.95Qty in Cart: 0Quantity:Price:$195.95Subtotal: -
PROX Piston Kit 01.1403.B
PROX
$195.95A piston kit is the heart of your engine's combustion cycle—wear or damage here directly impacts power delivery, fuel efficiency, and engine longevity. The PROX Piston Kit 01.1403.B delivers OEM-equivalent performance with precision manufacturing that...09100419- SKU:
- 09100419
- Availability:
- Ships Same Business Day
- Weight:
- 0.81 LBS
- BORE SIZE METRIC:
- 95.97 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 95.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$195.95Qty in Cart: 0Quantity:Price:$195.95Subtotal: -
PROX Piston Kit 01.4335.A
PROX
$179.95Worn or damaged pistons compromise engine compression, efficiency, and reliability—leading to power loss, increased fuel consumption, and potential catastrophic failure. The PROX Piston Kit 01.4335.A delivers OEM-spec performance with precision...09100425- SKU:
- 09100425
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 76.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.96 MM
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.4335.B
PROX
$188.95Factory piston performance starts with precision engineering—and the PROX Piston Kit 01.4335.B delivers exactly that. Built to OEM specifications using high-silicon aluminum alloy, this Japanese-manufactured kit ensures reliable power delivery and...09100426- SKU:
- 09100426
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- PISTON DIAMETER METRIC:
- 76.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.97 MM
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON KIT
$188.95 -
PROX Piston Kit 01.4335.C
PROX
$179.95Factory piston wear compromises compression, ring seal, and combustion efficiency—leading to power loss, increased blowby, and accelerated engine degradation. The PROX Piston Kit 01.4335.C restores OEM performance specifications with Japanese...09100427- SKU:
- 09100427
- Availability:
- Ships Same Business Day
- Weight:
- 0.56 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
- BORE SIZE METRIC:
- 76.98 MM
- PISTON DIAMETER METRIC:
- 76.98 MM
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON KIT
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.1222.A
PROX
$132.95A piston kit is one of the most critical components in engine performance and longevity. The PROX Piston Kit 01.1222.A delivers OEM-equivalent reliability with the precision engineering that high-performance engines demand. Whether you're rebuilding...09100428- SKU:
- 09100428
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- BORE SIZE METRIC:
- 53.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 53.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$132.95 -
PROX Piston Kit 01.1222.B
PROX
$105.95If your engine is showing signs of wear—loss of compression, increased blow-by, or worn ring grooves—a quality piston kit is your most direct path to restored performance and reliability. The PROX Piston Kit 01.1222.B delivers OEM-equivalent engineering...09100429- SKU:
- 09100429
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.95 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
$105.95Qty in Cart: 0Quantity:Price:$105.95Subtotal: -
PROX Piston Kit 01.3122.A
PROX
$99.95When your engine is running at the edge of performance, factory pistons become a liability. The PROX Piston Kit 01.3122.A delivers OEM-equivalent reliability with precision manufacturing that keeps your engine balanced and efficient through sustained...09100431- SKU:
- 09100431
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 47.94 MM
- BORE SIZE METRIC:
- 47.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$99.95 -
PROX Piston Kit 01.3122.B
PROX
$99.95A piston kit is the foundation of reliable engine performance—when factory pistons wear or fail, you need a direct OEM replacement that matches original specifications precisely. The PROX Piston Kit 01.3122.B delivers the exact geometry, material...09100432- SKU:
- 09100432
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- PISTON DIAMETER METRIC:
- 47.95 MM
- BORE SIZE METRIC:
- 47.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
$99.95 -
PROX Piston Kit 01.3224.A
PROX
$105.95A worn or damaged piston compromises combustion efficiency, fuel economy, and overall engine reliability. The PROX Piston Kit 01.3224.A delivers OEM-equivalent performance with precision engineering, giving you the confidence to push your engine to its...09100434- SKU:
- 09100434
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON DIAMETER METRIC:
- 53.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 53.95 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$105.95 -
PROX Piston Kit 01.3224.B
PROX
$101.95When your engine demands precision and reliability at high RPM, compromised pistons will cost you performance—and credibility. The PROX Piston Kit 01.3224.B delivers OEM-equivalent performance through Japanese engineering and CNC-machined accuracy,...09100435- SKU:
- 09100435
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- BORE SIZE METRIC:
- 53.96 MM
- PISTON DIAMETER METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$101.95Qty in Cart: 0Quantity:Price:$101.95Subtotal:
