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 Top End Gasket Set - Suzuki 35.3341
PROX
$69.95PROX Top End Gasket Set - Suzuki09345738- SKU:
- 09345738
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- UNITS:
- SET
- PRODUCT NAME:
- GASKET SET
- TYPE:
- TOP END
- RIDING STYLE:
- OFF-ROAD
$69.95 -
PROX Crank Bearing and Seal Kit 23.CBS22005
PROX
$59.95Made to exact OEM specifications for maximum performance and durability, Includes all necessary bearings/seals for a component's replacement, For use with OEM or Pro X crankshafts09240313- SKU:
- 09240313
- Availability:
- Ships Same Business Day
- Weight:
- 0.95 LBS
- APPLICATION:
- CRANKSHAFT
- PRODUCT NAME:
- BEARING AND SEAL KIT
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- TYPE:
- BALL
$59.95 -
PROX Crank Bearing and Seal Kit 23.CBS24001
PROX
$125.95Made to exact OEM specifications for maximum performance and durability, Includes all necessary bearings/seals for a component's replacement, For use with OEM or Pro X crankshafts09240327- SKU:
- 09240327
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
- STYLE:
- 4-STROKE
- TYPE:
- BALL
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- BEARING SET
- RIDING STYLE:
- STREET
$125.95 -
PROX Crank Bearing and Seal Kit 23.CBS41088
PROX
$33.95Made to exact OEM specifications for maximum performance and durability, Includes all necessary bearings/seals for a component's replacement, For use with OEM or Pro X crankshafts09240349- SKU:
- 09240349
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
- PRODUCT NAME:
- BEARING AND SEAL KIT
- TYPE:
- BALL
- STYLE:
- 2-STROKE
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$33.95 -
PROX Valve Shim Kit 29.VSA948
PROX
$109.95Made 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 shims09260941- SKU:
- 09260941
- Availability:
- Ships Same Business Day
- Weight:
- 1.14 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SHIM KIT
- TYPE:
- VALVE
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- ATV
- OUTSIDE DIAMETER METRIC:
- 9.48 MM
- RIDING STYLE:
- STREET
- VALVE SHIM THICKNESS METRIC:
- 1.20 MM - 3.50 MM
$109.95 -
PROX Valve Shim Kit 29.VSA748
PROX
$109.95Made 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 shims09261018- SKU:
- 09261018
- Availability:
- Ships Same Business Day
- Weight:
- 0.93 LBS
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SHIM KIT
- RIDING STYLE:
- UTV
- RIDING STYLE:
- WATERCRAFT
- TYPE:
- VALVE
- VALVE SHIM THICKNESS METRIC:
- 1.20 MM - 3.50 MM
- OUTSIDE DIAMETER METRIC:
- 7.48 MM
- RIDING STYLE:
- ATV
- RIDING STYLE:
- STREET
- UNITS:
- KIT
- RIDING STYLE:
- ADVENTURE TOURING / DUAL-SPORT
- RIDING STYLE:
- SNOW
$109.95 -
PROX Valve and Spring Kit 28.SIS2424-2
PROX
$195.95Replaces the OEM valves and valve springs, Steel, nitrided valves for increased durability and less wear under extreme conditions, Stronger valve springs deal with the extra weight of the steel valves, Springs are made from premium chrome vanadium steel...09261024- SKU:
- 09261024
- Availability:
- Ships Same Business Day
- Weight:
- 0.26 LBS
- PRODUCT NAME:
- SPRING KIT
- TYPE:
- VALVE
- MATERIAL:
- STEEL
- APPLICATION:
- INTAKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$195.95 -
PROX Valve and Spring Kit 28.SIS6329-2
PROX
$149.95Replaces the OEM valves and valve springs, Steel, nitrided valves for increased durability and less wear under extreme conditions, Stronger valve springs deal with the extra weight of the steel valves, Springs are made from premium chrome vanadium steel...09261436- SKU:
- 09261436
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SPRING KIT
- TYPE:
- VALVE
$149.95 -
PROX Valve and Spring Kit 28.SES4335-1
PROX
$149.95Replaces the OEM valves and valve springs, Steel, nitrided valves for increased durability and less wear under extreme conditions, Stronger valve springs deal with the extra weight of the steel valves, Springs are made from premium chrome vanadium steel...09261457- SKU:
- 09261457
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SPRING KIT
- MATERIAL:
- STEEL
- APPLICATION:
- EXHAUST
- TYPE:
- VALVE
$149.95 -
PROX Valve and Spring Kit 28.SIS2402-2
PROX
$195.95Replaces the OEM valves and valve springs, Steel, nitrided valves for increased durability and less wear under extreme conditions, Stronger valve springs deal with the extra weight of the steel valves, Springs are made from premium chrome vanadium steel...09261460- SKU:
- 09261460
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- PRODUCT NAME:
- SPRING KIT
- TYPE:
- VALVE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- APPLICATION:
- INTAKE
- UNITS:
- KIT
$195.95 -
PROX Piston Kit 01.1320.A2
PROX
$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,...PX4430C- SKU:
- PX4430C
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- RIDING STYLE:
- OFF-ROAD
- PISTON DIAMETER METRIC:
- 66.36 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- BORE SIZE METRIC:
- 66.36 MM
- PRODUCT NAME:
- PISTON KIT
- PISTON MATERIAL:
- ALUMINUM ALLOY
- UNITS:
- EACH
$139.95 -
PROX Exhaust Valve 28.6520-1
PROX
$54.95Manufactured to the highest precision and quality, Constructed to meet OEM specifications, Available in standard sizes only09260688- SKU:
- 09260688
- Availability:
- Ships Same Business Day
- Weight:
- 0.11 LBS
- RIDING STYLE:
- OFF-ROAD
- APPLICATION:
- EXHAUST
- MATERIAL:
- STEEL
- PRODUCT NAME:
- VALVE
- RIDING STYLE:
- ATV
- UNITS:
- EACH
$54.95 -
PROX Valve and Spring Kit 28.SIS1403-2
PROX
$139.95Replaces the OEM valves and valve springs, Steel, nitrided valves for increased durability and less wear under extreme conditions, Stronger valve springs deal with the extra weight of the steel valves, Springs are made from premium chrome vanadium steel...09261020- SKU:
- 09261020
- Availability:
- Ships Same Business Day
- Weight:
- 0.34 LBS
- APPLICATION:
- INTAKE
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SPRING KIT
- UNITS:
- KIT
- TYPE:
- VALVE
$139.95 -
PROX Connecting Rod Kit 03.6011
PROX
$109.95Come complete with crankpin, big-end bearing, small-end bearing and washers, Easy to install09230625- SKU:
- 09230625
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- PRODUCT NAME:
- CONNECTING ROD
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$109.95 -
PROX Crank Bearing and Seal Kit 23.CBS61003
PROX
$89.95Made to exact OEM specifications for maximum performance and durability, Includes all necessary bearings/seals for a component's replacement, For use with OEM or Pro X crankshafts09240360- SKU:
- 09240360
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
- PRODUCT NAME:
- BEARING AND SEAL KIT
- TYPE:
- BALL
- APPLICATION:
- CRANKSHAFT
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- 2-STROKE
- UNITS:
- KIT
$89.95 -
PROX Gasket Kit - Complete - KTM 34.6019
PROX
$94.95PROX Gasket Kit - Complete - KTM09345614- SKU:
- 09345614
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
- ENGINE TYPE:
- 2-STROKE
$94.95 -
Hinson Racing Engine Plug Kit for 2009-2016 Honda CRF450R EPK489
HINSON RACING
$69.99Upgrade your Honda's performance with the HINSON RACING Engine Plug Kit. Crafted from high-quality billet aluminum, this kit ensures durability and precision for optimal engine functionality. Proudly made in the U.S.A., it combines advanced engineering...09500539- SKU:
- 09500539
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- PLUG KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- MATERIAL:
- BILLET ALUMINUM
- TYPE:
- ENGINE
$69.99 -
Hinson Racing Engine Plug Kit for Honda CRF250R 2004-2017 EPK494
HINSON RACING
$69.99Experience unparalleled performance with the HINSON RACING Engine Plug Kit for Honda (EPK494). Crafted from high-quality billet aluminum, this kit is designed for durability and precision, ensuring a perfect fit for your engine. With its sleek design and...09500540- SKU:
- 09500540
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- COLOR/FINISH:
- BLACK
- MATERIAL:
- BILLET ALUMINUM
- PRODUCT NAME:
- PLUG KIT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- TYPE:
- ENGINE
$69.99 -
Hinson Racing Oil Filler Cap for Honda CR125R 1987-2007 OC154X
HINSON RACING
$19.99Upgrade your ATV's performance and aesthetics with the HINSON RACING Oil Filler Cap. Crafted from high-quality T-6 aluminum, this cap not only replaces the stock plastic plug but also enhances your ride with a sleek, factory-inspired look. Trusted by...09500614- SKU:
- 09500614
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
- RIDING STYLE:
- STREET
- PRODUCT NAME:
- CAP
- TYPE:
- OIL FILLER
- COLOR/FINISH:
- BLACK
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$19.99 -
Hinson Racing Oil Filler Cap Yamaha YZ85 2002-2022 OC213
HINSON RACING
$19.99Elevate your ATV's performance and aesthetics with the HINSON RACING Oil Filler Cap, expertly crafted from durable T-6 aluminum. This precision-engineered component not only replaces the standard plastic plug but also enhances your vehicle's overall...09500615- SKU:
- 09500615
- Availability:
- Ships Same Business Day
- Weight:
- 0.06 LBS
- UNITS:
- EACH
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- CAP
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- OIL FILLER
$19.99
