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 01.4406.C
PROX
$189.95When your engine is pushing limits, your pistons need to match that intensity. The PROX Piston Kit 01.4406.C delivers OEM-equivalent reliability with Japanese manufacturing precision, ensuring...09101158- SKU:
- 09101158
- Availability:
- Ships Same Business Day
- Weight:
- 0.92 LBS
- PISTON DIAMETER METRIC:
- 95.99 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.99 MM
- PRODUCT NAME:
- PISTON KIT
$189.95 -
PROX Piston Kit 01.6105.A
PROX
$105.95Your engine's heart deserves precision engineering built to last. The PROX Piston Kit 01.6105.A delivers OEM-grade reliability with the exacting tolerances demanded by both stock rebuilds and...09101159- SKU:
- 09101159
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 46.95 MM
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 46.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
$105.95 -
PROX Piston Kit 01.6105.B
PROX
$105.95When your engine's pistons wear beyond OEM tolerances, performance and reliability suffer. The PROX Piston Kit 01.6105.B delivers factory-spec replacement pistons engineered to restore combustion...09101160- SKU:
- 09101160
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- PISTON DIAMETER METRIC:
- 46.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 46.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
$105.95 -
PROX Piston Kit 01.6105.C
PROX
$105.95Piston failure cuts a race or rebuild short. The PROX Piston Kit 01.6105.C delivers OEM-equivalent reliability with precision engineering, ensuring your engine maintains peak combustion efficiency...09101161- SKU:
- 09101161
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- BORE SIZE METRIC:
- 46.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 46.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE C
- PRODUCT NAME:
- PISTON KIT
$105.95 -
PROX Piston Kit 01.6105.D
PROX
$105.95Your engine's pistons are the hardest-working components under the hood, cycling thousands of times per minute while managing extreme heat and pressure. When OEM pistons wear out or fail, you need a...09101162- SKU:
- 09101162
- Availability:
- Ships Same Business Day
- Weight:
- 0.28 LBS
- PISTON DIAMETER METRIC:
- 46.98 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 46.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE D
$105.95 -
PROX Piston Kit 01.6343.D
PROX
$166.95When your engine's pistons show wear, you're looking at compromised compression, increased blow-by, and accelerated internal degradation. The PROX Piston Kit 01.6343.D delivers OEM-equivalent...09101166- SKU:
- 09101166
- Availability:
- Ships Same Business Day
- Weight:
- 0.67 LBS
- PISTON DIAMETER METRIC:
- 66.37 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.37 MM
- PISTON SIZE METRIC:
- STANDARD SIZE D
- PRODUCT NAME:
- PISTON KIT
$166.95 -
PROX Piston Kit 01.6338.B
PROX
$209.99Whether you're rebuilding after high-mileage wear or preparing for sustained performance driving, a quality piston kit is essential to engine reliability and power delivery. The PROX Piston Kit 01...09101168- SKU:
- 09101168
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- PISTON DIAMETER METRIC:
- 75.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 75.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
$209.99Qty in Cart: 0Quantity:Price:$209.99Subtotal: -
PROX Piston Kit 01.6338.C
PROX
$209.99When your pistons show wear or you're rebuilding after high-mileage racing, you need a replacement that matches or exceeds OEM performance specifications. The PROX Piston Kit 01.6338.C delivers that...09101169- SKU:
- 09101169
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
- BORE SIZE METRIC:
- 75.98 MM
- PISTON DIAMETER METRIC:
- 75.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$209.99Qty in Cart: 0Quantity:Price:$209.99Subtotal: -
PROX Piston Kit 01.6427.A
PROX
$195.95Your engine's pistons are the workhorses converting combustion into power—and when they wear, performance suffers. The PROX Piston Kit 01.6427.A delivers OEM-equivalent reliability with precision...09101172- SKU:
- 09101172
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 94.94 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 96.94 MM
- PRODUCT NAME:
- PISTON KIT
$195.95Qty in Cart: 0Quantity:Price:$195.95Subtotal: -
PROX Piston Kit 01.6427.C
PROX
$195.95A piston kit is the heart of engine reliability and performance—worn or damaged pistons rob you of compression, efficiency, and power. The PROX Piston Kit 01.6427.C delivers OEM-equivalent quality...09101174- SKU:
- 09101174
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- BORE SIZE METRIC:
- 96.96 MM
- PISTON DIAMETER METRIC:
- 94.96 MM
- RIDING STYLE:
- ATV
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON KIT
$195.95Qty in Cart: 0Quantity:Price:$195.95Subtotal: -
PROX Piston Kit 01.6521.A
PROX
$214.95When your engine demands reliability under extreme conditions, OEM-spec pistons are non-negotiable. The PROX Piston Kit 01.6521.A delivers precision-engineered replacement pistons manufactured to...09101182- SKU:
- 09101182
- Availability:
- Ships Same Business Day
- Weight:
- 0.91 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 94.94 MM
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 94.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$214.95Qty in Cart: 0Quantity:Price:$214.95Subtotal: -
PROX Piston Kit 01.6521.B
PROX
$221.95When your engine is running on stock pistons, you're leaving performance on the table and risking catastrophic failure under sustained boost or high RPM loads. The PROX Piston Kit 01.6521.B delivers...09101183- SKU:
- 09101183
- Availability:
- Ships Same Business Day
- Weight:
- 0.91 LBS
- PISTON DIAMETER METRIC:
- 94.95 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 94.95 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- ATV
- UNITS:
- EACH
$221.95 -
PROX Piston Kit 01.6521.C
PROX
$221.95Worn or damaged pistons compromise engine efficiency, power delivery, and reliability—especially in high-demand racing and performance applications. The PROX Piston Kit 01.6521.C delivers...09101184- SKU:
- 09101184
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- BORE SIZE METRIC:
- 94.96 MM
- PISTON DIAMETER METRIC:
- 94.96 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
$221.95 -
PROX Piston Kit 01.1325.A
PROX
$139.95Factory-original performance demands factory-original components. The PROX Piston Kit 01.1325.A delivers OEM-specification reliability without compromise, engineered with precision-cast, high-silicon...09101187- SKU:
- 09101187
- Availability:
- Ships Same Business Day
- Weight:
- 0.71 LBS
- PISTON DIAMETER METRIC:
- 66.34 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.34 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Kit 01.1325.A1
PROX
$139.95Worn or damaged pistons compromise engine efficiency, boost consumption, and reliability—especially under high-performance conditions. The PROX Piston Kit 01.1325.A1 restores OEM-specification...09101188- SKU:
- 09101188
- Availability:
- Ships Same Business Day
- Weight:
- 0.71 LBS
- BORE SIZE METRIC:
- 66.35 MM
- PISTON DIAMETER METRIC:
- 66.35 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Kit 01.1363.000
PROX
$99.95Stock pistons wear out—and when they do, your engine's performance and reliability suffer. The PROX Piston Kit 01.1363.000 restores your engine to OEM specifications with precision-manufactured...09101365- SKU:
- 09101365
- Availability:
- Ships Same Business Day
- Weight:
- 0.49 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 65.50 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 65.50 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$99.95Qty in Cart: 0Quantity:Price:$99.95Subtotal: -
PROX Piston Kit 01.1363.050
PROX
$110.95A worn or damaged piston compromises engine efficiency, power delivery, and reliability. The PROX Piston Kit 01.1363.050 restores OEM-level performance with precision-engineered components...09101366- SKU:
- 09101366
- Availability:
- Ships Same Business Day
- Weight:
- 0.49 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON SIZE IMPERIAL:
- +0.050'
- PISTON DIAMETER METRIC:
- 66.00 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.00 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$110.95 -
PROX Piston Kit 01.1363.100
PROX
$99.95When your engine demands reliability and precision, OEM-quality pistons are non-negotiable. The PROX Piston Kit 01.1363.100 delivers factory-spec performance with CNC-machined tolerances that ensure...09101367- SKU:
- 09101367
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 66.50 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.50 MM
- PISTON SIZE IMPERIAL:
- 0.100'
- PRODUCT NAME:
- PISTON KIT
$99.95Qty in Cart: 0Quantity:Price:$99.95Subtotal: -
PROX Piston Kit 01.2225.A
PROX
$121.95A piston kit is one of the most critical components in your engine's combustion chamber—it directly impacts compression ratio, heat dissipation, and overall engine reliability. The PROX Piston Kit 01...09100594- SKU:
- 09100594
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.95 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 53.95 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
$121.95 -
PROX Piston Kit 01.2225.B
PROX
$121.95Your engine's pistons are the hardworking heart of combustion—they must withstand extreme pressure, temperature cycles, and precision tolerances that factory originals often compromise on after miles...09100595- SKU:
- 09100595
- Availability:
- Ships Same Business Day
- Weight:
- 0.41 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON DIAMETER METRIC:
- 53.96 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD SIZE B
- BORE SIZE METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
$121.95
