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 Connecting Rod 03.3108
PROX
MSRP: $109.95Now: $93.00Was: $109.95Comes complete with crankpin, big-end bearing, small-end bearing, and washers, Easy to install09230192- SKU:
- 09230192
- Availability:
- Ships Same Business Day
- Weight:
- 0.53 LBS
- PRODUCT NAME:
- CONNECTING ROD KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- ENGINE TYPE:
- 2-STROKE
- MATERIAL:
- FORGED STEEL
MSRP: $109.95Now: $93.00Was: $109.95Qty in Cart: 0Quantity:Price:MSRP: $109.95Now: $93.00Was: $109.95Subtotal: -
On Sale
PROX Connecting Rod 03.6351
PROX
MSRP: $179.95Now: $153.00Was: $179.95Comes complete with crankpin, big-end bearing, small-end bearing, and washers, Easy to install09230349- SKU:
- 09230349
- Availability:
- Ships Same Business Day
- Weight:
- 1.42 LBS
- ENGINE TYPE:
- 4-STROKE
- MATERIAL:
- FORGED STEEL
- PRODUCT NAME:
- CONNECTING ROD KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
MSRP: $179.95Now: $153.00Was: $179.95Qty in Cart: 0Quantity:Price:MSRP: $179.95Now: $153.00Was: $179.95Subtotal: -
On Sale
PROX Piston Kit 01.1323.C
PROX
MSRP: $139.95Now: $119.00Was: $139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX1322C- SKU:
- PX1322C
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE C
- BORE SIZE METRIC:
- 66.36 MM
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- PISTON DIAMETER METRIC:
- 66.36 MM
MSRP: $139.95Now: $119.00Was: $139.95Qty in Cart: 0Quantity:Price:MSRP: $139.95Now: $119.00Was: $139.95Subtotal: -
On Sale
PROX Ring Set 02.1208
PROX
MSRP: $24.95Now: $21.00Was: $24.95Manufactured in Japan and designed as OEM replacementsPX4210R- SKU:
- PX4210R
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- SET
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
MSRP: $24.95Now: $21.00Was: $24.95Qty in Cart: 0Quantity:Price:MSRP: $24.95Now: $21.00Was: $24.95Subtotal: -
On Sale
PROX Piston Kit 01.1208.A1
PROX
MSRP: $105.95Now: $90.00Was: $105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4240B- SKU:
- PX4240B
- Availability:
- Ships Same Business Day
- Weight:
- 0.38 LBS
- PRODUCT NAME:
- PISTON KIT
- PISTON DIAMETER METRIC:
- 53.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
MSRP: $105.95Now: $90.00Was: $105.95Qty in Cart: 0Quantity:Price:MSRP: $105.95Now: $90.00Was: $105.95Subtotal: -
On Sale
PROX Ring Set 02.1213
PROX
MSRP: $24.95Now: $21.00Was: $24.95Manufactured in Japan and designed as OEM replacementsPX4260R- SKU:
- PX4260R
- Availability:
- Ships Same Business Day
- Weight:
- 0.38 LBS
- PRODUCT NAME:
- PISTON RING
- UNITS:
- SET
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
MSRP: $24.95Now: $21.00Was: $24.95Qty in Cart: 0Quantity:Price:MSRP: $24.95Now: $21.00Was: $24.95Subtotal: -
On Sale
PROX Piston Kit 01.4108.B
PROX
MSRP: $89.95Now: $76.00Was: $89.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4280B- SKU:
- PX4280B
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PISTON DIAMETER METRIC:
- 47.95 MM
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE B
- UNITS:
- EACH
- BORE SIZE METRIC:
- 47.95 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $89.95Now: $76.00Was: $89.95Qty in Cart: 0Quantity:Price:MSRP: $89.95Now: $76.00Was: $89.95Subtotal: -
On Sale
PROX Ring Set 02.4100
PROX
MSRP: $24.95Now: $21.00Was: $24.95Manufactured in Japan and designed as OEM replacementsPX4290R- SKU:
- PX4290R
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- SET
MSRP: $24.95Now: $21.00Was: $24.95Qty in Cart: 0Quantity:Price:MSRP: $24.95Now: $21.00Was: $24.95Subtotal: -
On Sale
PROX Piston Kit 01.4213.C
PROX
MSRP: $105.95Now: $90.00Was: $105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4294C- SKU:
- PX4294C
- Availability:
- Ships Same Business Day
- Weight:
- 0.38 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.96 MM
- PISTON DIAMETER METRIC:
- 53.96 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $105.95Now: $90.00Was: $105.95Qty in Cart: 0Quantity:Price:MSRP: $105.95Now: $90.00Was: $105.95Subtotal: -
On Sale
PROX Ring Set 02.4305
PROX
MSRP: $39.95Now: $34.00Was: $39.95Manufactured in Japan and designed as OEM replacementsPX4305R- SKU:
- PX4305R
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- PRODUCT NAME:
- PISTON RING
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- SET
MSRP: $39.95Now: $34.00Was: $39.95Qty in Cart: 0Quantity:Price:MSRP: $39.95Now: $34.00Was: $39.95Subtotal: -
On Sale
PROX Ring Set 02.4312
PROX
MSRP: $39.95Now: $34.00Was: $39.95Manufactured in Japan and designed as OEM replacementsPX4308R- SKU:
- PX4308R
- Availability:
- Ships Same Business Day
- Weight:
- 0.04 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- SET
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- PISTON RING
MSRP: $39.95Now: $34.00Was: $39.95Qty in Cart: 0Quantity:Price:MSRP: $39.95Now: $34.00Was: $39.95Subtotal: -
On Sale
PROX Piston Kit 01.1315.A1
PROX
MSRP: $139.95Now: $119.00Was: $139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4420B- SKU:
- PX4420B
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- PISTON DIAMETER METRIC:
- 66.35 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.35 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $139.95Now: $119.00Was: $139.95 -
On Sale
PROX Piston Kit 01.1315.A2
PROX
MSRP: $139.95Now: $119.00Was: $139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4420C- SKU:
- PX4420C
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- BORE SIZE METRIC:
- 66.36 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 66.36 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $139.95Now: $119.00Was: $139.95Qty in Cart: 0Quantity:Price:MSRP: $139.95Now: $119.00Was: $139.95Subtotal: -
On Sale
PROX Piston Kit 01.1315.A3
PROX
MSRP: $139.95Now: $119.00Was: $139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4420D- SKU:
- PX4420D
- Availability:
- Ships Same Business Day
- Weight:
- 0.63 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON DIAMETER METRIC:
- 66.37 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- BORE SIZE METRIC:
- 66.37 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $139.95Now: $119.00Was: $139.95Qty in Cart: 0Quantity:Price:MSRP: $139.95Now: $119.00Was: $139.95Subtotal: -
On Sale
PROX Piston Kit 01.1320.A3
PROX
MSRP: $139.95Now: $119.00Was: $139.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX4430D- SKU:
- PX4430D
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 66.37 MM
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 66.37 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $139.95Now: $119.00Was: $139.95Qty in Cart: 0Quantity:Price:MSRP: $139.95Now: $119.00Was: $139.95Subtotal: -
On Sale
PROX Piston Kit 01.3310.D
PROX
MSRP: $129.95Now: $110.00Was: $129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5070D- SKU:
- PX5070D
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON DIAMETER METRIC:
- 66.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE D
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 66.96 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $129.95Now: $110.00Was: $129.95Qty in Cart: 0Quantity:Price:MSRP: $129.95Now: $110.00Was: $129.95Subtotal: -
On Sale
PROX Piston Kit 01.3310.E
PROX
MSRP: $129.95Now: $110.00Was: $129.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX5070E- SKU:
- PX5070E
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PISTON DIAMETER METRIC:
- 66.97 MM
- PISTON SIZE METRIC:
- STANDARD SIZE E
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 66.97 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
MSRP: $129.95Now: $110.00Was: $129.95Qty in Cart: 0Quantity:Price:MSRP: $129.95Now: $110.00Was: $129.95Subtotal: -
On Sale
PROX Piston Kit 01.2217.D
PROX
MSRP: $105.95Now: $90.00Was: $105.95Manufactured in Japan and designed to be OEM replacement, Cast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close tolerances, Pistons supplied in a kit package that includes rings,...PX7215D- SKU:
- PX7215D
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- EACH
- BORE SIZE METRIC:
- 53.98 MM
- PISTON DIAMETER METRIC:
- 53.98 MM
- PISTON SIZE METRIC:
- STANDARD
MSRP: $105.95Now: $90.00Was: $105.95 -
On Sale
PROX PRO-X Crank Seal Kit 42.2218
PROX
MSRP: $19.95Now: $17.00Was: $19.95OEM quality, All seals necessary for complete crank rebuild included094286- SKU:
- 094286
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $19.95Now: $17.00Was: $19.95Qty in Cart: 0Quantity:Price:MSRP: $19.95Now: $17.00Was: $19.95Subtotal: -
On Sale
PROX PRO-X Crank Seal Kit 42.2318
PROX
MSRP: $14.95Now: $13.00Was: $14.95OEM quality, All seals necessary for complete crank rebuild included094287- SKU:
- 094287
- Availability:
- Ships Same Business Day
- Weight:
- 0.08 LBS
MSRP: $14.95Now: $13.00Was: $14.95Qty in Cart: 0Quantity:Price:MSRP: $14.95Now: $13.00Was: $14.95Subtotal:
