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
-
PROX Piston Kit 01.4415.C
PROX
$189.95A worn or damaged piston directly compromises engine compression, power delivery, and longevity—requiring immediate replacement to restore factory performance and reliability. The PROX Piston Kit 01...09103909- SKU:
- 09103909
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- PISTON DIAMETER METRIC:
- 95.99 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.99 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.2412.B
PROX
$179.95When your engine demands reliability at high RPM, factory pistons often can't deliver the precision fit and durability required for sustained performance. The PROX Piston Kit 01.2412.B is engineered...09102733- SKU:
- 09102733
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 76.96 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 76.96 MM
- RIDING STYLE:
- OFF-ROAD
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston - SuperJet 700 01.2510.100
PROX
$129.95The PROX Piston for SuperJet 700 delivers the reliability and precision your watercraft demands during high-performance operation. A quality piston is critical to maintaining compression, power...09102740- SKU:
- 09102740
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- ENGINE TYPE:
- 2-STROKE
- BORE SIZE METRIC:
- 82.00 MM
- PISTON MATERIAL:
- ALUMINUM
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- WATERCRAFT
$129.95 -
PROX Piston Kit - 300EXC TPI '18-'19 01.6388.C
PROX
$189.95When your 300EXC TPI demands peak performance, a worn or damaged piston compromises compression, throttle response, and engine reliability. The PROX Piston Kit delivers OEM-equivalent quality with...09106268- SKU:
- 09106268
- Availability:
- Ships Same Business Day
- Weight:
- 0.78 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- PISTON KIT
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit - Beta RR300 '18-'19 01.7398.B
PROX
$221.95Your Beta RR300 demands precision engine internals that match factory specifications without compromise. This PROX piston kit is engineered in Japan with high-silicon aluminum and CNC machining to...09106269- SKU:
- 09106269
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$221.95 -
PROX Piston Kit - Standard - Yamaha PW50/80 01.2005.000
PROX
$79.95The PROX Piston Kit is engineered to deliver reliable performance and extended service life in demanding offroad conditions. Whether you're rebuilding a worn engine or refreshing your Yamaha PW50/80...09106097- SKU:
- 09106097
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- BORE SIZE METRIC:
- 40.00 MM
- PRODUCT NAME:
- PISTON KIT
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE - OVERSIZE:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$79.95 -
PROX Piston Kit - Yamaha SJ 700 01.2510.000
PROX
$129.95Off-road riding demands pistons that withstand extreme heat, pressure, and rapid acceleration cycles—factory units often fall short under sustained performance conditions. The PROX Piston Kit...09106099- SKU:
- 09106099
- Availability:
- Ships Same Business Day
- Weight:
- 1.05 LBS
- BORE SIZE METRIC:
- 81.00 MM
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
- RIDING STYLE:
- WATERCRAFT
$129.95 -
PROX Piston Kit - Yamaha SJ 700 01.2510.050
PROX
$138.95The PROX Piston Kit is engineered for demanding offroad conditions where stock pistons fall short on durability and heat management. Built to withstand the extreme pressures and temperatures of...09106100- SKU:
- 09106100
- Availability:
- Ships Same Business Day
- Weight:
- 1.05 LBS
- BORE SIZE METRIC:
- 81.50 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- KIT
$138.95Qty in Cart: 0Quantity:Price:$138.95Subtotal: -
PROX Piston Kit 01.3001.000
PROX
$79.95High-performance piston kits are essential for offroad engines pushing beyond stock limits—whether you're running increased boost, higher RPMs, or extreme terrain. The PROX Piston Kit 01.3001.000...09106101- SKU:
- 09106101
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- RIDING STYLE:
- ATV
- UNITS:
- KIT
- BORE SIZE METRIC:
- 41.00 MM
- PRODUCT NAME:
- PISTON KIT
$79.95 -
PROX Piston Kit - Standard - KTM 50SX 01.6012.A
PROX
$77.95The PROX Piston Kit is engineered to restore your KTM 50SX to factory performance specifications or serve as a critical replacement when wear compromises combustion efficiency and power delivery. A...09106102- SKU:
- 09106102
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 39.46 MM
- UNITS:
- KIT
- PRODUCT NAME:
- PISTON KIT
$77.95 -
PROX Piston Kit - Standard - KTM 50SX 01.6012.B
PROX
$77.95A quality piston kit is fundamental to maintaining peak engine performance and longevity in high-demand offroad riding. The PROX Piston Kit delivers OEM-grade reliability with precision-engineered...09106103- SKU:
- 09106103
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
- BORE SIZE METRIC:
- 39.47 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$77.95 -
PROX Piston Kit - Standard - KTM 65SX 01.6022.A
PROX
$77.95The PROX Piston Kit is engineered to restore your KTM 65SX to factory performance specifications or serve as a reliable replacement for high-mileage engines. Whether you're a weekend rider or a young...09106104- SKU:
- 09106104
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE - OVERSIZE:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE METRIC:
- 44.96 MM
$77.95 -
PROX Piston Kit - Standard - KTM 65SX 01.6022.B
PROX
$77.95The PROX Piston Kit restores your KTM 65SX to OEM specifications with precision-engineered components built to handle the demands of competitive off-road riding. Whether you're rebuilding after a...09106105- SKU:
- 09106105
- Availability:
- Ships Same Business Day
- Weight:
- 0.12 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 44.97 MM
$77.95 -
PROX Piston Kit - Standard - 125SX 01.6220.A
PROX
$124.95Off-road performance demands pistons engineered for extreme conditions—high RPMs, aggressive throttle response, and sustained heat. The PROX Piston Kit delivers the reliability and precision fit your...09106106- SKU:
- 09106106
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- BORE SIZE METRIC:
- 53.94 MM
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$124.95 -
PROX Piston Kit - Standard - KTM 200EXC 01.6249.A
PROX
$139.95The PROX Piston Kit keeps your KTM 200EXC running at peak efficiency through the demands of aggressive off-road riding. When stock pistons wear or fail, you lose compression, power delivery, and fuel...09106108- SKU:
- 09106108
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
- BORE - OVERSIZE:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE METRIC:
- STANDARD
- BORE SIZE METRIC:
- 63.94 MM
- PRODUCT NAME:
- PISTON KIT
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Rings 02.1227
PROX
$49.95Piston rings are critical to engine longevity—they seal combustion pressure, manage blow-by, and transfer heat away from the piston crown. PROX Piston Rings 02.1227 deliver optimized heat transfer...09120647- SKU:
- 09120647
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- PAIR
- PISTON MATERIAL:
- ALUMINUM ALLOY
- BORE SIZE METRIC:
- 65.97 MM - 65.99 MM
$49.95 -
PROX Piston Rings 02.1340
PROX
$49.95Piston rings are critical to engine efficiency—they seal combustion pressure, control oil consumption, and manage heat transfer from the piston to the cylinder wall. PROX Piston Rings 02.1340 deliver...09120648- SKU:
- 09120648
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- BORE SIZE METRIC:
- 76.77 MM - 76.79 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- PAIR
$49.95Qty in Cart: 0Quantity:Price:$49.95Subtotal: -
PROX Piston Rings 02.3408
PROX
$49.95Piston rings are the critical seal between your combustion chamber and crankcase—poor sealing means lost compression, blow-by, and reduced power output. PROX Piston Rings 02.3408 deliver precise...09120649- SKU:
- 09120649
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 95.96 MM - 95.98 MM
- UNITS:
- PAIR
$49.95Qty in Cart: 0Quantity:Price:$49.95Subtotal: -
PROX Piston Rings 02.3340
PROX
$49.95Proper piston ring sealing is fundamental to engine efficiency and longevity. PROX Piston Rings 02.3340 deliver optimized heat transfer and gas sealing, which directly impacts combustion efficiency,...09120651- SKU:
- 09120651
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- BORE SIZE METRIC:
- 76.96 MM - 76.98 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- PAIR
- PRODUCT NAME:
- PISTON RING
$49.95Qty in Cart: 0Quantity:Price:$49.95Subtotal: -
PROX Piston Rings 02.3337
PROX
$44.95Piston rings are critical to engine performance—they seal combustion pressure, regulate oil consumption, and manage heat transfer between the piston and cylinder wall. Worn or inferior rings cause...09120653- SKU:
- 09120653
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- BORE SIZE METRIC:
- 76.96 MM - 76.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- PAIR
$44.95
