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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Wiseco Piston Ring Set 85mm Bore 1995-2000 Polaris Scrambler 400 3347TD
WISECO
$57.95Piston ring seal integrity is critical for maintaining compression, controlling blow-by, and maximizing fuel efficiency in high-demand riding conditions. The Wiseco 3347TD delivers precision-engineered rings that work seamlessly with Wiseco pistons,...3347TD- SKU:
- 3347TD
- Availability:
- Ships Same Business Day
- Weight:
- 0.02 LBS
- PRODUCT NAME:
- PISTON RING
- BORE SIZE METRIC:
- 85.00 MM
- RIDING STYLE:
- ATV
- PISTON MATERIAL:
- ALUMINUM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- SET
$57.95 -
Wiseco Piston Kit 57mm Oversize for Yamaha DT125 1974-1981 236M05700
WISECO
$154.95A worn or damaged piston directly compromises your DT125's combustion efficiency, throttle response, and engine longevity. The Wiseco 236M05700 restores full power output and reliability with precision-engineered geometry and aerospace-grade materials...236M05700- SKU:
- 236M05700
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- MODEL:
- FORGED SERIES
- SKIRT COATING:
- NON-COATED
- BORE - OVERSIZE:
- +1,00 MM
- PRODUCT NAME:
- PISTON KIT
- BORE SIZE METRIC:
- 57.00 MM
- STROKE LENGTH METRIC:
- 50.00 MM
- BORE - OVERSIZE METRIC:
- +1.00 MM
- DISPLACEMENT:
- 123 CC
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 56.95 MM
- PISTON MATERIAL:
- 4032 ALUMINUM ALLOY
- RIDING STYLE:
- ATV
- UNITS:
- KIT
$154.95Qty in Cart: 0Quantity:Price:$154.95Subtotal: -
HOT RODS Water Pump Shaft HRSHA-002
HOT RODS
$63.95A worn water pump shaft compromises cooling system integrity and accelerates seal degradation, leading to leaks and potential engine overheating. The HOT RODS Water Pump Shaft HRSHA-002 restores OE-specification performance with precision engineering and...09500575- SKU:
- 09500575
- Availability:
- Ships Same Business Day
- Weight:
- 0.14 LBS
- TYPE:
- WATER PUMP
- PRODUCT NAME:
- SHAFT
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
$63.95 -
HOT RODS Water Pump Shaft HRSHA-001
HOT RODS
$63.95A worn water pump shaft compromises cooling system efficiency and invites premature seal failure—both risks that can sideline your engine. This OE-quality replacement restores proper coolant circulation with a polished surface finish that minimizes...09500574- SKU:
- 09500574
- Availability:
- Ships Same Business Day
- Weight:
- 0.13 LBS
- TYPE:
- WATER PUMP
- PRODUCT NAME:
- SHAFT
- RIDING STYLE:
- STREET
- UNITS:
- EACH
$63.95 -
BOYESEN Impeller/Waterpump Cover WPK06AM
BOYESEN
$194.95Engine cooling efficiency directly impacts performance, reliability, and longevity—especially under sustained high-RPM operation. The BOYESEN Impeller/Waterpump Cover WPK06AM delivers measurably higher coolant flow across all RPM ranges, maintaining...09400897- SKU:
- 09400897
- Availability:
- Ships Same Business Day
- Weight:
- 0.34 LBS
- COLOR/FINISH:
- POWDER-COATED
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
- RIDING STYLE:
- OFF-ROAD
- BASE FINISH:
- POWDER-COATED
- UNITS:
- KIT
- TYPE:
- WATER PUMP
- COLOR/FINISH:
- MAGNESIUM
- MATERIAL:
- ALUMINUM
$194.95 -
BOYESEN Impeller/Waterpump Cover WPK06AB
BOYESEN
$194.95Engine temperatures are a direct threat to longevity and performance—especially under sustained load. The BOYESEN Impeller/Waterpump Cover WPK06AB delivers increased coolant flow across all RPM ranges, keeping your engine running at consistent, optimal...09400896- SKU:
- 09400896
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- BASE COLOR:
- BLACK
- BASE FINISH:
- POWDER-COATED
- COLOR/FINISH:
- BLACK
- COLOR/FINISH:
- POWDER-COATED
- MATERIAL:
- ALUMINUM
- MODEL:
- SUPERCOOLER
- PRODUCT NAME:
- COVER AND IMPELLER KIT
$194.95 -
HOT RODS Output Shaft Seal OSK0057
HOT RODS
$26.95A leaking countershaft seal doesn't just waste oil—it compromises lubrication, invites contaminants into your transmission, and can lead to catastrophic failure if ignored. The HOT RODS Output Shaft Seal kit (OSK0057) eliminates the guesswork by bundling...09350955- SKU:
- 09350955
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- PRODUCT NAME:
- SEAL KIT
- TYPE:
- OIL
- UNITS:
- KIT
- APPLICATION:
- COUNTERSHAFT
- RIDING STYLE:
- OFF-ROAD
$26.95Qty in Cart: 0Quantity:Price:$26.95Subtotal: -
HOT RODS Output Shaft Seal OSK0058
HOT RODS
$35.95Countershaft seal leaks can compromise transmission reliability and lead to costly damage if left unaddressed. The HOT RODS Output Shaft Seal kit (OSK0058) provides everything needed to repair the leak in a single, complete package—eliminating the hassle...09350954- SKU:
- 09350954
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- APPLICATION:
- COUNTERSHAFT
- TYPE:
- OIL
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- SEAL KIT
- UNITS:
- KIT
$35.95 -
Cylinder Works YZ250 1999-2024 Big Bore Power Valve Kit CW-PV-K02
CYLINDER WORKS
$394.95The YZ250 power valve is critical to your engine's mid-range and top-end performance—restrict its movement, and you're leaving horsepower on the table. Cylinder Works' big bore kit restores optimal valve function with CNC precision, directly improving...09350953- SKU:
- 09350953
- Availability:
- Ships Same Business Day
- Weight:
- 0.35 LBS
- COLOR/FINISH:
- ANODIZED
- MATERIAL:
- STEEL
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- POWER VALVE
- BORE SIZE METRIC:
- 72.00 MM
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$394.95 -
Cylinder Works Power Valve Kit Standard Bore Yamaha YZ250 1999-2021 CW-PV-K01
CYLINDER WORKS
$252.95The YZ250's power valve is critical to maximizing mid-range punch and throttle response—and a worn or poorly-designed unit robs you of significant horsepower across the entire powerband. The Cylinder Works CW-PV-K01 restores precision control over your...09350952- SKU:
- 09350952
- Availability:
- Ships Same Business Day
- Weight:
- 0.15 LBS
- MATERIAL:
- STEEL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE METRIC:
- STOCK BORE CYLINDER
- COLOR/FINISH:
- BLACK
- PRODUCT NAME:
- POWER VALVE
- COLOR/FINISH:
- ANODIZED
$252.95 -
COMETIC Crank Seal Kit C7803
COMETIC
$17.95A compromised crank seal is an invisible threat to engine integrity—leaking oil, inviting contamination, and accelerating internal wear. The COMETIC Crank Seal Kit C7803 delivers OE-equivalent sealing performance with the precision engineering that...09350811- SKU:
- 09350811
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- CRANKSHAFT
- TYPE:
- OIL
$17.95Qty in Cart: 0Quantity:Price:$17.95Subtotal: -
HOT RODS Seal Output Shaft OSK0030
HOT RODS
$29.95A leaking countershaft seal will degrade your transmission's performance and lead to catastrophic failure if left unchecked. This complete kit from Hot Rods eliminates the guesswork by bundling everything needed to seal the leak in one purchase, saving...09350593- SKU:
- 09350593
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$29.95Qty in Cart: 0Quantity:Price:$29.95Subtotal: -
HOT RODS Seal Output Shaft OSK0029
HOT RODS
$37.95A leaking countershaft seal drains performance and reliability from your transmission, leaving you stranded trackside or compromising engine longevity. The HOT RODS Seal Output Shaft kit delivers everything needed to stop the leak and restore proper...09350592- SKU:
- 09350592
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SEAL
$37.95 -
HOT RODS Seal Output Shaft OSK0026
HOT RODS
$35.95A leaking countershaft seal will compromise your transmission's integrity and lead to catastrophic failure if left unaddressed. This complete kit eliminates guesswork by bundling every component you need to restore a proper seal in one purchase, saving...09350590- SKU:
- 09350590
- Availability:
- Ships Same Business Day
- Weight:
- 0.14 LBS
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SEAL
$35.95 -
HOT RODS Seal Output Shaft OSK0020
HOT RODS
$31.95A leaking countershaft seal will compromise your transmission's integrity and lead to costly damage if left unaddressed. This complete repair kit eliminates the need to source multiple components separately, getting your bike back to reliable operation...09350584- SKU:
- 09350584
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$31.95 -
HOT RODS Seal Output Shaft OSK0019
HOT RODS
$37.95A leaking countershaft seal will degrade your transmission fluid and compromise gear engagement—repair it right the first time with a complete rebuild kit. HOT RODS bundles everything you need to eliminate shaft leakage and restore proper sealing without...09350583- SKU:
- 09350583
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
$37.95 -
HOT RODS Seal Output Shaft OSK0018
HOT RODS
$37.95A leaking countershaft seal compromises your transmission's integrity and can lead to costly damage if left unaddressed. The HOT RODS Seal Output Shaft kit delivers everything you need to fix the problem in one complete package—no hunting for individual...09350582- SKU:
- 09350582
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$37.95 -
HOT RODS Seal Output Shaft OSK0015
HOT RODS
$34.95A leaking countershaft seal creates cascading problems—oil loss, bearing contamination, and potential drivetrain failure. The HOT RODS Seal Output Shaft kit eliminates guesswork by delivering everything you need in a single, proven package, saving you...09350580- SKU:
- 09350580
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- PRODUCT NAME:
- SEAL
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
$34.95 -
HOT RODS Seal Output Shaft OSK0013
HOT RODS
$38.95A leaking countershaft seal can compromise your transmission's integrity and lead to costly damage if left unaddressed. This complete kit eliminates the guesswork by bundling everything needed for a proper repair in one purchase. Get back to reliable...09350579- SKU:
- 09350579
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- PRODUCT NAME:
- SEAL
$38.95 -
HOT RODS Seal Output Shaft OSK0012
HOT RODS
$34.95A leaking countershaft seal will compromise your transmission's integrity and lead to costly damage if left unaddressed. This complete kit eliminates the guesswork by bundling every component needed for a proper repair in one order. Get your drivetrain...09350578- SKU:
- 09350578
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- APPLICATION:
- COUNTERSHAFT
- APPLICATION:
- TRANSMISSION
- PRODUCT NAME:
- SEAL
$34.95
