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 Valve Shims - 5 pack 29.748130
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size, Inexpensive and easy replacement for expensive OEM shims09260872- SKU:
- 09260872
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 1.30 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shims - 5 pack 29.748200
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size, Inexpensive and easy replacement for expensive OEM shims09260886- SKU:
- 09260886
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 2.00 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shims - 5 pack 29.748255
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size, Inexpensive and easy replacement for expensive OEM shims09260897- SKU:
- 09260897
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 2.55 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shims - 5 pack 29.748300
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size, Inexpensive and easy replacement for expensive OEM shims09260906- SKU:
- 09260906
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 3.00 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
MSRP: $9.95Now: $8.00Was: $9.95 -
On Sale
PROX Valve Shims - 5 pack 29.748305
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size, Inexpensive and easy replacement for expensive OEM shims09260907- SKU:
- 09260907
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 3.05 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
MSRP: $9.95Now: $8.00Was: $9.95 -
On Sale
PROX Valve Shims - 5 pack 29.748315
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size, Inexpensive and easy replacement for expensive OEM shims09260909- SKU:
- 09260909
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 3.15 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948120
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260942- SKU:
- 09260942
- Availability:
- Ships Same Business Day
- Weight:
- 0.01 LBS
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 1.20 MM
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948130
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260944- SKU:
- 09260944
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- VALVE SHIM THICKNESS METRIC:
- 1.30 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948135
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260945- SKU:
- 09260945
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 1.35 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- WATERCRAFT
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948150
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260948- SKU:
- 09260948
- Availability:
- Ships Same Business Day
- Weight:
- 0.05 LBS
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- VALVE SHIM THICKNESS METRIC:
- 1.50 MM
- RIDING STYLE:
- WATERCRAFT
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948280
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260974- SKU:
- 09260974
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 2.80 MM
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948300
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260978- SKU:
- 09260978
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- RIDING STYLE:
- ATV
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- STREET
- RIDING STYLE:
- UTV
- VALVE SHIM THICKNESS METRIC:
- 3.00 MM
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948310
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260980- SKU:
- 09260980
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 3.10 MM
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948315
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260981- SKU:
- 09260981
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- WATERCRAFT
- UNITS:
- 5 PACK
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 3.15 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- UTV
- TYPE:
- VALVE
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Valve Shim - 5 pack 29.948325
PROX
MSRP: $9.95Now: $8.00Was: $9.95Made using a specific heat-treatment to ensure hardness for maximum durability and less wear, Precision machined to match exact size09260983- SKU:
- 09260983
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
- RIDING STYLE:
- UTV
- UNITS:
- 5 PACK
- RIDING STYLE:
- STREET
- RIDING STYLE:
- WATERCRAFT
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- OFF-ROAD
- RIDING STYLE:
- ATV
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 3.25 MM
MSRP: $9.95Now: $8.00Was: $9.95Qty in Cart: 0Quantity:Price:MSRP: $9.95Now: $8.00Was: $9.95Subtotal: -
On Sale
PROX Piston Kit 01.4409.C
PROX
MSRP: $189.95Now: $161.00Was: $189.95Manufactured 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,...09101467- SKU:
- 09101467
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
- BORE SIZE METRIC:
- 95.99 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 95.99 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- PISTON SIZE METRIC:
- STANDARD SIZE C
- UNITS:
- EACH
MSRP: $189.95Now: $161.00Was: $189.95Qty in Cart: 0Quantity:Price:MSRP: $189.95Now: $161.00Was: $189.95Subtotal: -
On Sale
PROX Piston Kit 01.6604.A
PROX
MSRP: $229.95Now: $195.00Was: $229.95Manufactured 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,...09101523- SKU:
- 09101523
- Availability:
- Ships Same Business Day
- Weight:
- 1.18 LBS
- PISTON DIAMETER METRIC:
- 100.94 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 100.94 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- UNITS:
- EACH
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON KIT
MSRP: $229.95Now: $195.00Was: $229.95Qty in Cart: 0Quantity:Price:MSRP: $229.95Now: $195.00Was: $229.95Subtotal: -
On Sale
PROX Piston Kit 01.3408.A
PROX
MSRP: $189.95Now: $161.00Was: $189.95Manufactured 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,...09101556- SKU:
- 09101556
- Availability:
- Ships Same Business Day
- Weight:
- 0.86 LBS
- BORE SIZE METRIC:
- 95.96 MM
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 95.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $189.95Now: $161.00Was: $189.95Qty in Cart: 0Quantity:Price:MSRP: $189.95Now: $161.00Was: $189.95Subtotal: -
On Sale
PROX Piston Kit 01.3408.B
PROX
MSRP: $189.95Now: $161.00Was: $189.95Manufactured 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,...09101557- SKU:
- 09101557
- Availability:
- Ships Same Business Day
- Weight:
- 0.86 LBS
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- PISTON SIZE METRIC:
- STANDARD SIZE B
- BORE SIZE METRIC:
- 95.97 MM
- PISTON DIAMETER METRIC:
- 95.97 MM
- PRODUCT NAME:
- PISTON KIT
MSRP: $189.95Now: $161.00Was: $189.95Qty in Cart: 0Quantity:Price:MSRP: $189.95Now: $161.00Was: $189.95Subtotal: -
On Sale
PROX Piston Kit 01.2409.B
PROX
MSRP: $179.95Now: $153.00Was: $179.95Manufactured 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,...09101610- SKU:
- 09101610
- Availability:
- Ships Same Business Day
- Weight:
- 0.53 LBS
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 76.96 MM
- PISTON SIZE METRIC:
- STANDARD SIZE B
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 76.96 MM
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
MSRP: $179.95Now: $153.00Was: $179.95Qty in Cart: 0Quantity:Price:MSRP: $179.95Now: $153.00Was: $179.95Subtotal:
