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
-
On Sale
PROX Ring Set 02.2314
PROX
MSRP: $49.95Now: $42.00Was: $49.95Piston ring sets are critical to engine longevity and performance—they seal combustion pressure, regulate oil consumption, and maintain compression consistency across the entire powerband. The PROX Ring Set 02.2314 delivers OEM-grade quality with...PX7080R- SKU:
- PX7080R
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
- UNITS:
- SET
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
MSRP: $49.95Now: $42.00Was: $49.95Qty in Cart: 0Quantity:Price:MSRP: $49.95Now: $42.00Was: $49.95Subtotal: -
On Sale
PROX Piston Kit 01.2321.A
PROX
MSRP: $132.95Now: $110.00Was: $132.95Factory piston performance demands precision engineering and material integrity—two hallmarks of the PROX Piston Kit 01.2321.A. Whether you're rebuilding after high-mileage wear or seeking the reliability of OEM-equivalent specifications, this...PX7130A- SKU:
- PX7130A
- Availability:
- Ships Same Business Day
- Weight:
- 0.69 LBS
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 66.35 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.35 MM
MSRP: $132.95Now: $110.00Was: $132.95 -
On Sale
PROX Piston Kit 01.2321.B
PROX
MSRP: $132.95Now: $110.00Was: $132.95Worn or damaged pistons compromise engine efficiency, power delivery, and reliability—especially under high-load conditions. The PROX Piston Kit 01.2321.B restores your engine to OEM performance specifications with precision-manufactured components...PX7130B- SKU:
- PX7130B
- Availability:
- Ships Same Business Day
- Weight:
- 0.69 LBS
- BORE SIZE METRIC:
- 66.36 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 66.36 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
MSRP: $132.95Now: $110.00Was: $132.95 -
On Sale
PROX Piston Kit 01.2321.C
PROX
MSRP: $132.95Now: $110.00Was: $132.95Worn or damaged pistons compromise compression, fuel efficiency, and engine reliability—often requiring a complete teardown to address. The PROX Piston Kit 01.2321.C delivers OEM-equivalent performance with precision engineering, allowing you to restore...PX7130C- SKU:
- PX7130C
- Availability:
- Ships Same Business Day
- Weight:
- 0.65 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 66.37 MM
- BORE SIZE METRIC:
- 66.37 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $132.95Now: $110.00Was: $132.95 -
On Sale
PROX Piston Kit 01.2321.D
PROX
MSRP: $132.95Now: $110.00Was: $132.95A worn or damaged piston compromises combustion efficiency, reduces power output, and accelerates engine wear. The PROX Piston Kit 01.2321.D restores OEM performance specifications with precision-engineered components manufactured to exacting tolerances...PX7130D- SKU:
- PX7130D
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- BORE SIZE METRIC:
- 66.38 MM
- PISTON DIAMETER METRIC:
- 66.38 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE D
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PRODUCT NAME:
- PISTON KIT
MSRP: $132.95Now: $110.00Was: $132.95 -
On Sale
PROX Piston Kit 01.2215.C
PROX
MSRP: $121.95Now: $90.00Was: $121.95A piston kit is the foundation of reliable engine performance—worn or damaged pistons compromise compression, power delivery, and longevity. The PROX Piston Kit 01.2215.C delivers OEM-equivalent quality without the OEM price tag, using precision...PX7214C- SKU:
- PX7214C
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- BORE SIZE METRIC:
- 53.96 MM
- ENGINE TYPE:
- 2-STROKE
- PRODUCT NAME:
- PISTON KIT
- PISTON SIZE METRIC:
- +0.02 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 53.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $121.95Now: $90.00Was: $121.95 -
On Sale
PROX Piston Kit 01.2217.A
PROX
MSRP: $121.95Now: $90.00Was: $121.95Worn or damaged pistons compromise engine compression, throttle response, and fuel efficiency—leaving you stranded or forced into costly rebuilds. The PROX Piston Kit 01.2217.A restores your engine to OEM performance specs with precision-engineered...PX7215A- SKU:
- PX7215A
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- STANDARD
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 53.95 MM
- PISTON DIAMETER METRIC:
- 53.95 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $121.95Now: $90.00Was: $121.95 -
On Sale
PROX Piston Kit 01.2217.B
PROX
MSRP: $121.95Now: $90.00Was: $121.95If you're rebuilding an engine or restoring performance after high-mileage wear, piston quality directly impacts reliability, compression consistency, and longevity under load. The PROX Piston Kit 01.2217.B delivers OEM-specification performance with...PX7215B- SKU:
- PX7215B
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- PISTON DIAMETER METRIC:
- 53.96 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.96 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- +0.01 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $121.95Now: $90.00Was: $121.95 -
On Sale
PROX Piston Kit 01.2217.C
PROX
MSRP: $105.95Now: $90.00Was: $105.95When your engine demands precision engineering and proven reliability, OEM-equivalent performance becomes non-negotiable. The PROX Piston Kit 01.2217.C delivers the exact specifications your engine was designed around, manufactured to exacting tolerances...PX7215C- SKU:
- PX7215C
- Availability:
- Ships Same Business Day
- Weight:
- 0.44 LBS
- ENGINE TYPE:
- 2-STROKE
- PISTON SIZE METRIC:
- +0.02 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 53.97 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 53.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $105.95Now: $90.00Was: $105.95Qty in Cart: 0Quantity:Price:MSRP: $105.95Now: $90.00Was: $105.95Subtotal: -
On Sale
PROX PRO-X Crank Seal Kit 42.2102
PROX
MSRP: $10.95Now: $8.00Was: $10.95A compromised crank seal allows oil seepage that degrades engine performance and can lead to catastrophic failure if left unaddressed. The PROX PRO-X Crank Seal Kit 42.2102 delivers OEM-quality seals in a complete package, eliminating the need to source...094280- SKU:
- 094280
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $10.95Now: $8.00Was: $10.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.2319
PROX
MSRP: $22.95Now: $17.00Was: $22.95A worn or leaking crankshaft seal can compromise engine integrity and lead to costly oil loss and contamination. The PROX PRO-X Crank Seal Kit 42.2319 delivers OEM-quality seals engineered to restore proper crankshaft sealing during a complete rebuild,...094288- SKU:
- 094288
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.2321
PROX
MSRP: $22.95Now: $17.00Was: $22.95A worn crank seal compromises engine integrity and invites oil leakage that compounds over time. This complete kit eliminates guesswork during crank rebuilds, delivering OEM-specification seals across all critical pressure points. Whether you're...094289- SKU:
- 094289
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.2221
PROX
MSRP: $22.95Now: $17.00Was: $22.95A compromised crank seal can silently undermine your engine's reliability, causing oil weeping, contamination, and catastrophic failure if left unaddressed. The PROX PRO-X Crank Seal Kit 42.2221 delivers complete, OEM-quality seals engineered to restore...094290- SKU:
- 094290
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.3316
PROX
MSRP: $29.95Now: $25.00Was: $29.95A compromised crank seal is an invisible threat to engine reliability—leaking oil where it shouldn't, contaminating your combustion chamber, and accelerating wear on critical components. The PROX PRO-X Crank Seal Kit 42.3316 delivers OEM-quality seals in...094395- SKU:
- 094395
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
MSRP: $29.95Now: $25.00Was: $29.95Qty in Cart: 0Quantity:Price:MSRP: $29.95Now: $25.00Was: $29.95Subtotal: -
On Sale
PROX PRO-X Crank Seal Kit 42.3219
PROX
MSRP: $25.95Now: $21.00Was: $25.95A worn or leaking crankshaft seal can undermine your engine's reliability and lead to costly oil loss and contamination. The PROX PRO-X Crank Seal Kit 42.3219 supplies all necessary seals for a complete crankshaft rebuild, restoring proper compression...094398- SKU:
- 094398
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $25.95Now: $21.00Was: $25.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.4105
PROX
MSRP: $10.95Now: $8.00Was: $10.95A failing crank seal compromises oil containment and invites contamination into your engine's most critical rotating assembly. This complete kit eliminates the guesswork during rebuilds by providing every seal specification needed for a proper, leak-free...094481- SKU:
- 094481
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $10.95Now: $8.00Was: $10.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.4208
PROX
MSRP: $22.95Now: $17.00Was: $22.95A compromised crank seal is a silent killer—it allows oil to weep past critical bearing surfaces, leading to catastrophic engine failure if left unaddressed. The PROX PRO-X Crank Seal Kit 42.4208 delivers OEM-equivalent seals with the precision...094484- SKU:
- 094484
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $22.95Now: $17.00Was: $22.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.4288
PROX
MSRP: $9.95Now: $8.00Was: $9.95A compromised crank seal can silently undermine engine reliability, leading to oil leaks, contamination, and catastrophic failure during critical race moments or long-term ownership. The PROX PRO-X Crank Seal Kit 42.4288 delivers OEM-quality seals in a...094487- SKU:
- 094487
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX PRO-X Crank Seal Kit 42.4300
PROX
MSRP: $30.95Now: $25.00Was: $30.95A worn or leaking crank seal compromises engine compression, increases oil consumption, and accelerates internal wear—all problems that compound quickly under racing conditions or high-mileage street use. The PROX PRO-X Crank Seal Kit 42.4300 provides...094488- SKU:
- 094488
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $30.95Now: $25.00Was: $30.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.4403
PROX
MSRP: $9.95Now: $8.00Was: $9.95A failing crank seal compromises engine compression, invites oil contamination, and accelerates wear on critical internal components. This complete kit delivers OEM-quality seals engineered to restore proper crankshaft sealing during a full rebuild,...094489- SKU:
- 094489
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $9.95Now: $8.00Was: $9.95
