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 01.4342.C
PROX
$179.95When your engine demands reliability under extreme conditions, OEM-spec pistons are non-negotiable. The PROX Piston Kit 01.4342.C delivers factory-equivalent performance with precision Japanese...09104544- SKU:
- 09104544
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 76.98 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 76.98 MM
- RIDING STYLE:
- OFF-ROAD
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.6226.D
PROX
$143.95A piston failure or wear means catastrophic engine damage and costly downtime. The PROX Piston Kit 01.6226.D restores your engine to OEM specifications with precision-engineered components that...09104549- SKU:
- 09104549
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 53.97 MM
- BORE SIZE METRIC:
- 53.97 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$143.95Qty in Cart: 0Quantity:Price:$143.95Subtotal: -
PROX Piston Kit 01.1232.B
PROX
$177.95Worn or damaged pistons rob your engine of compression, power, and reliability. The PROX Piston Kit 01.1232.B delivers OEM-equivalent performance with precision engineering that restores your engine...09103252- SKU:
- 09103252
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 65.98 MM
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 65.98 MM
$177.95 -
PROX Piston Kit 01.1413.A
PROX
$195.95When your engine demands precision and reliability, OEM-quality pistons are non-negotiable. The PROX Piston Kit 01.1413.A delivers factory-spec performance with Japanese engineering and CNC-machined...09103254- SKU:
- 09103254
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 95.96 MM
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD
- BORE SIZE METRIC:
- 95.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON KIT
$195.95Qty in Cart: 0Quantity:Price:$195.95Subtotal: -
PROX Piston Kit 01.6394.C
PROX
$189.95When your engine demands reliability under extreme conditions, OEM-equivalent pistons are non-negotiable. The PROX Piston Kit 01.6394.C delivers Japanese manufacturing precision with a high-silicon...09103259- SKU:
- 09103259
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- BORE SIZE METRIC:
- 71.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD
- PISTON DIAMETER METRIC:
- 71.96 MM
- RIDING STYLE:
- OFF-ROAD
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit 01.2414.C
PROX
$179.95When your engine's pistons show signs of wear or you're rebuilding after high-mileage service, choosing the right replacement is critical to maintaining peak performance and reliability. The PROX...09103422- SKU:
- 09103422
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 76.97 MM
- PISTON DIAMETER METRIC:
- 76.97 MM
- RIDING STYLE:
- OFF-ROAD
$179.95Qty in Cart: 0Quantity:Price:$179.95Subtotal: -
PROX Piston Kit 01.6228.B
PROX
$139.95A piston kit is fundamental to engine reliability and performance—worn or damaged pistons compromise compression, fuel efficiency, and power delivery. The PROX Piston Kit 01.6228.B delivers...09103438- SKU:
- 09103438
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 55.95 MM
- PISTON DIAMETER METRIC:
- 55.95 MM
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Kit 01.6228.C
PROX
$139.95Piston failure compromises engine reliability and performance—whether you're rebuilding after competition or restoring original capability. The PROX Piston Kit 01.6228.C delivers OEM-equivalent...09103439- SKU:
- 09103439
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
- PISTON DIAMETER METRIC:
- 55.96 MM
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 55.96 MM
- PRODUCT NAME:
- PISTON KIT
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Kit - 300EXC TPI 01.6388.B
PROX
$189.95Your 300EXC TPI deserves piston internals that match factory precision without compromise. This OEM-spec replacement kit restores compression and reliability while maintaining the tight tolerances...09106267- SKU:
- 09106267
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$189.95Qty in Cart: 0Quantity:Price:$189.95Subtotal: -
PROX Piston Kit - Standard - Yamaha PW80 01.2008.000
PROX
$93.95The PROX Piston Kit delivers the reliability and precision your Yamaha PW80 demands in demanding off-road conditions. Factory-spec pistons ensure proper bore fit, ring sealing, and heat...09106098- SKU:
- 09106098
- Availability:
- Ships Same Business Day
- Weight:
- 0.14 LBS
- BORE SIZE METRIC:
- 47.00 MM
- PRODUCT NAME:
- PISTON KIT
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$93.95Qty in Cart: 0Quantity:Price:$93.95Subtotal: -
PROX Piston Kit - Standard - KTM 125SX 01.6220.B
PROX
$124.95The PROX Piston Kit is engineered for the demanding demands of off-road racing, delivering the reliability and precision your KTM 125SX demands at high RPM. OEM pistons wear quickly under competition...09106107- SKU:
- 09106107
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE METRIC:
- 53.95 MM
- PRODUCT NAME:
- PISTON KIT
$124.95Qty in Cart: 0Quantity:Price:$124.95Subtotal: -
PROX Piston Kit - Standard - 200EXC 01.6249.B
PROX
$139.95The PROX Piston Kit maintains optimal compression and durability in high-demand off-road conditions, ensuring consistent performance lap after lap. Whether you're pushing your 200EXC to its limits on...09106109- SKU:
- 09106109
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
- BORE SIZE METRIC:
- 63.95 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
$139.95Qty in Cart: 0Quantity:Price:$139.95Subtotal: -
PROX Piston Rings 02.4336
PROX
$49.95Proper piston ring selection is critical for engine reliability and performance—substandard rings lead to blow-by, oil consumption, and power loss. PROX Piston Rings 02.4336 deliver optimized heat...09120655- SKU:
- 09120655
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- BORE SIZE METRIC:
- 76.96 MM - 76.98 MM
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- PAIR
$49.95Qty in Cart: 0Quantity:Price:$49.95Subtotal: -
PROX Piston Rings 02.6351
PROX
$49.95Piston rings are critical to engine longevity—they maintain compression, control oil consumption, and manage heat dissipation under extreme combustion pressures. PROX Piston Rings 02.6351 deliver...09120661- SKU:
- 09120661
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- UNITS:
- PAIR
- BORE SIZE METRIC:
- 87.96 MM - 87.98 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON RING
$49.95Qty in Cart: 0Quantity:Price:$49.95Subtotal: -
PROX Crank Bearing and Seal Kit 23.CBS12007
PROX
$105.95A crankshaft bearing failure can sideline your engine and derail race day—this PROX kit eliminates that risk with OEM-specification bearings and seals engineered for reliability under extreme...09240295- SKU:
- 09240295
- Availability:
- Ships Same Business Day
- Weight:
- 0.90 LBS
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 4-STROKE
- PRODUCT NAME:
- BEARING AND SEAL KIT
- UNITS:
- KIT
- TYPE:
- BALL
- APPLICATION:
- CRANKSHAFT
$105.95Qty in Cart: 0Quantity:Price:$105.95Subtotal: -
PROX Crank Bearing and Seal Kit 23.CBS12080
PROX
$55.95A worn or damaged crankshaft bearing and seal assembly compromises engine reliability and performance—especially in high-RPM or forced-induction applications where precision tolerances are critical...09240296- SKU:
- 09240296
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- APPLICATION:
- CRANKSHAFT
- PRODUCT NAME:
- BEARING AND SEAL KIT
- UNITS:
- KIT
- TYPE:
- BALL
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
$55.95Qty in Cart: 0Quantity:Price:$55.95Subtotal: -
PROX Crank Bearing and Seal Kit 23.CBS13006
PROX
$116.95A crankshaft rebuild demands precision—substandard bearings and seals invite catastrophic failure and lost performance. This PROX kit eliminates guesswork by delivering OEM-spec components engineered...09240299- SKU:
- 09240299
- Availability:
- Ships Same Business Day
- Weight:
- 1.05 LBS
- PRODUCT NAME:
- BEARING AND SEAL KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
- STYLE:
- 4-STROKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$116.95 -
PROX Crank Bearing and Seal Kit 23.CBS13087
PROX
$70.95A crank bearing and seal failure can sideline your engine—and your race season. This PROX kit eliminates guesswork by delivering factory-precise replacements engineered to exact OEM specifications,...09240301- SKU:
- 09240301
- Availability:
- Ships Same Business Day
- Weight:
- 1.65 LBS
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
- PRODUCT NAME:
- BEARING AND SEAL KIT
- RIDING STYLE:
- ATV
- STYLE:
- 2-STROKE
- UNITS:
- KIT
$70.95 -
PROX Crank Bearing and Seal Kit 23.CBS23080
PROX
$70.95A worn crankshaft bearing or seal failure can destroy an entire engine build. The PROX Crank Bearing and Seal Kit 23.CBS23080 gives you a complete, OEM-specification replacement solution that...09240321- SKU:
- 09240321
- Availability:
- Ships Same Business Day
- Weight:
- 1.80 LBS
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
- PRODUCT NAME:
- BEARING AND SEAL KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- BALL
$70.95Qty in Cart: 0Quantity:Price:$70.95Subtotal: -
PROX Crank Bearing and Seal Kit 23.CBS33094
PROX
$75.95A crankshaft rebuild is only as good as its bearings and seals—weak components here will compromise power transfer and engine longevity. The PROX 23.CBS33094 kit eliminates guesswork by delivering...09240343- SKU:
- 09240343
- Availability:
- Ships Same Business Day
- Weight:
- 1.50 LBS
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- STYLE:
- 2-STROKE
- PRODUCT NAME:
- BEARING AND SEAL KIT
- TYPE:
- BALL
$75.95Qty in Cart: 0Quantity:Price:$75.95Subtotal:
