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 - 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 quality piston kit directly impacts throttle response,...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 tolerances, ensuring consistent compression and reduced...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 racer pushing hard on the track, a quality piston kit...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 season of hard racing or performing preventative...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 125SX needs to maintain peak power delivery across...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 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 and sealing performance, ensuring reliable compression...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 02.3337
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 compression loss, blow-by, and premature engine wear...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 -
PROX Piston Rings 02.6225
PROX
$49.95Piston rings are the critical interface between your pistons and cylinder walls—they seal combustion pressure, manage blow-by, and transfer heat away from the combustion chamber. PROX Piston Rings 02.6225 deliver the precision engineering needed to...09120657- SKU:
- 09120657
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.94 MM - 53.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON RING
- UNITS:
- PAIR
$49.95 -
PROX Crank Bearing and Seal Kit 23.CBS11085
PROX
$59.95A worn or compromised crankshaft bearing and seal assembly will kill your engine's reliability and performance faster than almost any other failure point. This PROX kit delivers OEM-spec replacements that restore your crank to factory tolerances,...09240294- SKU:
- 09240294
- Availability:
- Ships Same Business Day
- Weight:
- 0.92 LBS
- PRODUCT NAME:
- BEARING AND SEAL KIT
- STYLE:
- 2-STROKE
- TYPE:
- BALL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
$59.95 -
PROX Crank Bearing and Seal Kit 23.CBS12086
PROX
$57.95A failed crank bearing or seal will leave you stranded—and replacement with inferior components compounds the problem. This PROX kit delivers OEM-spec precision engineering, ensuring your crankshaft operates with the durability and reliability you need...09240297- SKU:
- 09240297
- Availability:
- Ships Same Business Day
- Weight:
- 0.95 LBS
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
- PRODUCT NAME:
- BEARING AND SEAL KIT
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
$57.95 -
PROX Crank Bearing and Seal Kit 23.CBS13084
PROX
$70.95A complete crank bearing and seal kit is non-negotiable when you're rebuilding or servicing your crankshaft—skimping on these components invites catastrophic failure under load. The PROX 23.CBS13084 delivers OEM-specification precision across all bearing...09240300- SKU:
- 09240300
- Availability:
- Ships Same Business Day
- Weight:
- 1.50 LBS
- APPLICATION:
- CRANKSHAFT
- PRODUCT NAME:
- BEARING AND SEAL KIT
- TYPE:
- BALL
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
$70.95 -
PROX Crank Bearing and Seal Kit 23.CBS14096
PROX
$85.95A crankshaft is only as reliable as its bearings and seals—neglect either, and you're risking catastrophic engine failure. The PROX Crank Bearing and Seal Kit 23.CBS14096 gives you a complete, OEM-spec replacement solution that restores your crankshaft...09240306- SKU:
- 09240306
- Availability:
- Ships Same Business Day
- Weight:
- 1.75 LBS
- APPLICATION:
- CRANKSHAFT
- PRODUCT NAME:
- BEARING SET
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- STYLE:
- 4-STROKE
- TYPE:
- BALL
$85.95 -
PROX Crank Bearing and Seal Kit 23.CBS21081
PROX
$38.95A properly sealed and supported crankshaft is foundational to reliable engine performance and longevity. This PROX Crank Bearing and Seal Kit delivers OEM-specification components, eliminating the guesswork and risk of mixing incompatible parts during a...09240308- SKU:
- 09240308
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
- PRODUCT NAME:
- BEARING AND SEAL KIT
$38.95 -
PROX Crank Bearing and Seal Kit 23.CBS21083
PROX
$59.95A crankshaft rebuild demands precision—substandard bearings and seals invite catastrophic failure and costly downtime. This PROX kit delivers OEM-exact specifications for reliable durability, whether you're running a stock bottom end or pairing it with a...09240310- SKU:
- 09240310
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- APPLICATION:
- CRANKSHAFT
- STYLE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- BEARING AND SEAL KIT
- TYPE:
- BALL
$59.95 -
PROX Crank Bearing and Seal Kit 23.CBS21093
PROX
$36.95A compromised crankshaft bearing or seal can cascade into catastrophic engine failure—and downtime you can't afford. This PROX kit delivers OEM-spec replacements for both bearings and seals, ensuring your crank runs true and your engine stays sealed...09240311- SKU:
- 09240311
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- STYLE:
- 2-STROKE
- PRODUCT NAME:
- BEARING AND SEAL KIT
- TYPE:
- BALL
$36.95 -
PROX Crank Bearing and Seal Kit 23.CBS22079
PROX
$39.95A crankshaft rebuild demands precision—any wear in the bearing surfaces or seal integrity compromises engine reliability and performance. The PROX Crank Bearing and Seal Kit 23.CBS22079 delivers OEM-specification components that restore your crankshaft...09240314- SKU:
- 09240314
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
- PRODUCT NAME:
- BEARING AND SEAL KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
$39.95 -
PROX Crank Bearing and Seal Kit 23.CBS22080
PROX
$38.95A failed crank bearing or seal will sideline your engine faster than any mechanical failure—this PROX kit gives you everything needed for a complete, reliable rebuild without sourcing multiple components separately. Whether you're refreshing an OEM...09240315- SKU:
- 09240315
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
- PRODUCT NAME:
- BEARING AND SEAL KIT
$38.95 -
PROX Crank Bearing and Seal Kit 23.CBS22086
PROX
$70.95A worn crank bearing and seal kit compromises engine reliability and performance—exactly what you can't afford during a rebuild or overhaul. This PROX kit delivers OEM-specification components engineered to restore your crankshaft to factory tolerances,...09240316- SKU:
- 09240316
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- UNITS:
- KIT
- STYLE:
- 2-STROKE
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- BEARING AND SEAL KIT
- TYPE:
- BALL
$70.95 -
PROX Crank Bearing and Seal Kit 23.CBS22098
PROX
$70.95A quality crank bearing and seal kit is non-negotiable for engine reliability and longevity—especially when you're pushing your machine to its limits. The PROX 23.CBS22098 delivers OEM-spec components that restore your crankshaft assembly to factory...09240318- SKU:
- 09240318
- Availability:
- Ships Same Business Day
- Weight:
- 0.95 LBS
- PRODUCT NAME:
- BEARING AND SEAL KIT
- STYLE:
- 2-STROKE
- TYPE:
- BALL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
$70.95 -
PROX Crank Bearing and Seal Kit 23.CBS23001
PROX
$70.95A worn crankshaft bearing or seal failure will sideline your engine and derail your season. This PROX kit delivers all the bearings and seals you need to restore your crank to OEM specifications without guesswork or compatibility issues. Whether you're...09240320- SKU:
- 09240320
- Availability:
- Ships Same Business Day
- Weight:
- 1.55 LBS
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
- PRODUCT NAME:
- BEARING AND SEAL KIT
$70.95
