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Harley Engine

Harley Engine

Harley Engine

Harley Bike Engine Parts at JJ Motorsports

Rebuild and boost your Harley's engine with premium parts from JJ Motorsports. Our inventory features complete gasket sets, piston kits, oil filters, pushrod tubes, and coolers designed for maximum strength, leak-free sealing, and high-performance in extreme conditions. Compatible with Big Twins, Softail, Touring, and more, these components support top-end overhauls, oil management, and durability for street rides or custom builds.

Shop trusted brands like Drag Specialties for magnetic filters and Wiseco for forged pistons. Explore related categories such as Harley air and fuel for carb tuning or Harley drivetrain for transmission upgrades.

Top Harley Engine Products

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
  • JAMES GASKET Timing Gear Cover - Big Twin 25225-36-C

    JAMES GASKET Timing Gear Cover - Big Twin 25225-36-C

    JAMES GASKET

    $29.10
    A leaking cam chest gasket compromises engine reliability and creates a messy, unprofessional appearance in your engine bay. The JAMES GASKET Timing Gear Cover is engineered to seal the critical interface between your cam chest and cover, preventing oil...
    DS174510
    SKU:
    DS174510
    Availability:
    Ships Same Business Day
    Weight:
    0.38 LBS
    PRODUCT NAME:
    GASKET
    THICKNESS IMPERIAL:
    0,020'
    THICKNESS METRIC:
    0.51 MM
    UNITS:
    10 PACK
    MATERIAL:
    PAPER
    RIDING STYLE:
    STREET
    THICKNESS:
    0,51 MM (0,020')
    TYPE:
    CAM COVER
    $29.10
    Qty in Cart: 0
    Quantity:
    Price:
    $29.10
    Subtotal:
  • JAMES GASKET Head Gasket with Silicon - 3-5/8" - .045" 16773-85-TS

    JAMES GASKET Head Gasket with Silicon - 3-5/8" - .045" 16773-85-TS

    JAMES GASKET

    $59.20
    A quality head gasket is the foundation of cylinder sealing integrity—it's what stands between efficient combustion and catastrophic leak-down. The JAMES GASKET Head Gasket with Silicon delivers reliable, long-term compression retention on naturally...
    DS174500
    SKU:
    DS174500
    Availability:
    Ships Same Business Day
    Weight:
    0.75 LBS
    BORE SIZE:
    3,625'
    BORE SIZE IMPERIAL:
    3.625'
    THICKNESS:
    1,14 MM (0,045')
    TYPE:
    CYLINDER HEAD
    MATERIAL:
    SILICONE
    PRODUCT NAME:
    GASKET
    THICKNESS METRIC:
    1.14 MM
    UNITS:
    5 PACK
    RIDING STYLE:
    STREET
    THICKNESS IMPERIAL:
    0,045'
    $59.20
    Qty in Cart: 0
    Quantity:
    Price:
    $59.20
    Subtotal:
  • JAMES GASKET Keihin Manifold Gasket - Big Twin 27077-78

    JAMES GASKET Keihin Manifold Gasket - Big Twin 27077-78

    JAMES GASKET

    $9.50
    A deteriorating intake manifold gasket will kill your Big Twin's reliability and fuel atomization, leading to lean conditions, heat damage, and potential air leaks. The JAMES GASKET Keihin Manifold Gasket kit gives you OEM-quality seals designed...
    DS174492
    SKU:
    DS174492
    Availability:
    Ships Same Business Day
    Weight:
    0.20 LBS
    RIDING STYLE:
    STREET
    TYPE:
    CARBURETOR
    MATERIAL:
    PAPER
    PRODUCT NAME:
    GASKET
    TYPE:
    INTAKE MANIFOLD
    UNITS:
    10 PACK
    $9.50
    Qty in Cart: 0
    Quantity:
    Price:
    $9.50
    Subtotal:
  • JAMES GASKET Shifter Shaft Seal 11148

    JAMES GASKET Shifter Shaft Seal 11148

    JAMES GASKET

    $19.81
    A leaking shifter shaft seal compromises your transmission's integrity and can lead to costly fluid loss and internal damage. The JAMES GASKET Shifter Shaft Seal 11148 delivers OEM-grade sealing performance with precision engineering, ensuring your...
    DS174489
    SKU:
    DS174489
    Availability:
    Ships Same Business Day
    Weight:
    0.02 LBS
    APPLICATION:
    GEAR SHIFT LEVER
    TYPE:
    QUAD SEAL
    RIDING STYLE:
    STREET
    PRODUCT NAME:
    X-RING
    UNITS:
    25 PACK
    $19.81
    Qty in Cart: 0
    Quantity:
    Price:
    $19.81
    Subtotal:
  • JAMES GASKET Starter Shaft Oil Seal - Big Twin 31341-80DL

    JAMES GASKET Starter Shaft Oil Seal - Big Twin 31341-80DL

    JAMES GASKET

    $14.50
    The starter shaft oil seal is a critical component that prevents oil leakage from your Big Twin engine's crankcase—a common failure point that can lead to messy garage floors and potential engine damage if left unchecked. JAMES GASKET's OEM-specification...
    DS174486
    SKU:
    DS174486
    Availability:
    Ships Same Business Day
    Weight:
    0.08 LBS
    RIDING STYLE:
    STREET
    PRODUCT NAME:
    SEAL
    APPLICATION:
    STARTER SHAFT
    UNITS:
    5 PACK
    $14.50
    Qty in Cart: 0
    Quantity:
    Price:
    $14.50
    Subtotal:
  • On Sale
    JAMES GASKET Upper Rocker Cork - XL 17354-86

    JAMES GASKET Upper Rocker Cork - XL 17354-86

    JAMES GASKET

    Now: $19.00
    Was: $25.00
    A properly sealed upper rocker cover is non-negotiable for keeping oil where it belongs—inside your engine. This JAMES GASKET cork gasket combines proven materials with precision engineering to deliver a leak-free seal that holds up under sustained heat...
    DS174484
    SKU:
    DS174484
    Availability:
    Ships Same Business Day
    Weight:
    0.13 LBS
    RIDING STYLE:
    STREET
    TYPE:
    ROCKER BOX
    PRODUCT NAME:
    GASKET
    MOUNTING POSITION:
    UPPER
    UNITS:
    5 PACK
    MATERIAL:
    CORK
    Now: $19.00
    Was: $25.00
    Qty in Cart: 0
    Quantity:
    Price:
    Now: $19.00
    Was: $25.00
    Subtotal:
  • JAMES GASKET Lower Rocker Cork - XL 17353-86

    JAMES GASKET Lower Rocker Cork - XL 17353-86

    JAMES GASKET

    $45.60
    A properly sealed rocker cover gasket is fundamental to preventing oil leakage and maintaining engine cleanliness—two factors that directly impact long-term reliability and performance. The JAMES GASKET Lower Rocker Cork combines proven elastomer sealing...
    DS174483
    SKU:
    DS174483
    Availability:
    Ships Same Business Day
    Weight:
    0.13 LBS
    MOUNTING POSITION:
    LOWER
    RIDING STYLE:
    STREET
    TYPE:
    ROCKER BOX
    UNITS:
    5 PACK
    PRODUCT NAME:
    GASKET
    MATERIAL:
    CORK
    $45.60
    Qty in Cart: 0
    Quantity:
    Price:
    $45.60
    Subtotal:
  • JAMES GASKET Oil Pump Body Gasket - Big Twin 26245-41

    JAMES GASKET Oil Pump Body Gasket - Big Twin 26245-41

    JAMES GASKET

    $14.00
    Oil seepage from your pump body isn't just messy—it's a sign of gasket failure that can lead to inadequate lubrication and catastrophic engine damage. The JAMES GASKET Oil Pump Body Gasket is engineered to provide a reliable seal on Big Twin engines,...
    DS174480
    SKU:
    DS174480
    Availability:
    Ships Same Business Day
    Weight:
    0.02 LBS
    MATERIAL:
    PAPER
    PRODUCT NAME:
    GASKET
    STYLE:
    BODY
    RIDING STYLE:
    STREET
    TYPE:
    OIL PUMP
    UNITS:
    10 PACK
    $14.00
    Qty in Cart: 0
    Quantity:
    Price:
    $14.00
    Subtotal:
  • JAMES GASKET Rear Base Gasket - FL/FX 16777-63

    JAMES GASKET Rear Base Gasket - FL/FX 16777-63

    JAMES GASKET

    $16.60
    A leaking rear base gasket compromises engine integrity and creates ongoing maintenance headaches. The JAMES GASKET Rear Base Gasket eliminates the need for gasket sealer, delivering a reliable, factory-quality seal that holds up to repeated heat cycles...
    DS174479
    SKU:
    DS174479
    Availability:
    Ships Same Business Day
    Weight:
    0.19 LBS
    RIDING STYLE:
    STREET
    UNITS:
    10 PACK
    MATERIAL:
    PAPER
    THICKNESS METRIC:
    0.81 MM
    PRODUCT NAME:
    GASKET
    THICKNESS IMPERIAL:
    0,032'
    TYPE:
    CYLINDER BASE
    $16.60
    Qty in Cart: 0
    Quantity:
    Price:
    $16.60
    Subtotal:
  • JAMES GASKET Kick Shaft Oil Seal - XL/Big Twin 33076-37

    JAMES GASKET Kick Shaft Oil Seal - XL/Big Twin 33076-37

    JAMES GASKET

    $11.80
    A failing crankshaft oil seal is a silent threat to your engine's longevity—once it starts weeping, internal lubrication fails and bearing damage accelerates. The JAMES GASKET Kick Shaft Oil Seal is precision-engineered to maintain a perfect barrier...
    DS174478
    SKU:
    DS174478
    Availability:
    Ships Same Business Day
    Weight:
    0.02 LBS
    PRODUCT NAME:
    SEAL
    UNITS:
    10 PACK
    APPLICATION:
    CRANKSHAFT
    APPLICATION:
    KICKSTARTER
    RIDING STYLE:
    STREET
    $11.80
    Qty in Cart: 0
    Quantity:
    Price:
    $11.80
    Subtotal:
  • JAMES GASKET Shifter Cam Shaft Seal 34036-36

    JAMES GASKET Shifter Cam Shaft Seal 34036-36

    JAMES GASKET

    $11.10
    A leaking shifter cam shaft seal compromises transmission reliability and creates costly fluid loss on the track and street. The JAMES GASKET Shifter Cam Shaft Seal 34036-36 delivers OEM-quality sealing performance with proven durability in high-demand...
    DS174477
    SKU:
    DS174477
    Availability:
    Ships Same Business Day
    Weight:
    0.02 LBS
    PRODUCT NAME:
    SEAL
    UNITS:
    10 PACK
    APPLICATION:
    SHIFTER SHAFT
    APPLICATION:
    TRANSMISSION
    RIDING STYLE:
    STREET
    $11.10
    Qty in Cart: 0
    Quantity:
    Price:
    $11.10
    Subtotal:
  • JAMES GASKET Mainshaft Seal - Big Twin 12044-A

    JAMES GASKET Mainshaft Seal - Big Twin 12044-A

    JAMES GASKET

    $14.95
    The mainshaft seal is a critical component that prevents transmission fluid from leaking into your primary case, a common failure point on Big Twin engines. A worn or degraded seal will cause oil loss, contaminate your primary fluid, and accelerate wear...
    DS174476
    SKU:
    DS174476
    Availability:
    Ships Same Business Day
    Weight:
    0.02 LBS
    APPLICATION:
    TRANSMISSION
    RIDING STYLE:
    STREET
    APPLICATION:
    MAIN DRIVE GEAR
    PRODUCT NAME:
    SEAL
    UNITS:
    EACH
    $14.95
    Qty in Cart: 0
    Quantity:
    Price:
    $14.95
    Subtotal:
  • JAMES GASKET Main Drive Gear Seal 12013-A

    JAMES GASKET Main Drive Gear Seal 12013-A

    JAMES GASKET

    $9.50
    A leaking main drive gear seal can compromise your entire drivetrain, allowing oil loss and contamination that degrades performance and shortens component life. The JAMES GASKET Main Drive Gear Seal 12013-A delivers OEM-equivalent sealing integrity with...
    DS174475
    SKU:
    DS174475
    Availability:
    Ships Same Business Day
    Weight:
    0.04 LBS
    UNITS:
    5 PACK
    PRODUCT NAME:
    SEAL
    RIDING STYLE:
    STREET
    APPLICATION:
    MAIN DRIVE GEAR
    APPLICATION:
    MAINSHAFT
    $9.50
    Qty in Cart: 0
    Quantity:
    Price:
    $9.50
    Subtotal:
  • JAMES GASKET Pushrod Cork - Big Twin 37337-36

    JAMES GASKET Pushrod Cork - Big Twin 37337-36

    JAMES GASKET

    $24.40
    A worn or failing pushrod cork gasket compromises engine sealing and can lead to oil leakage, increased blowby, and potential internal damage. JAMES GASKET's pushrod cork delivers reliable sealing for Big Twin engines with OEM-equivalent quality and...
    DS174474
    SKU:
    DS174474
    Availability:
    Ships Same Business Day
    Weight:
    0.04 LBS
    APPLICATION:
    CLUTCH PUSHROD
    RIDING STYLE:
    STREET
    PRODUCT NAME:
    SEAL
    UNITS:
    10 PACK
    $24.40
    Qty in Cart: 0
    Quantity:
    Price:
    $24.40
    Subtotal:
  • JAMES GASKET Rocker Arm Cover Gasket 17541-48-A

    JAMES GASKET Rocker Arm Cover Gasket 17541-48-A

    JAMES GASKET

    $27.50
    A rocker arm cover gasket is your first line of defense against oil seepage that compromises engine cleanliness and performance. When factory gaskets deteriorate or fail, oil weeps onto your engine bay, attracting dirt and potentially fouling spark plug...
    DS174470
    SKU:
    DS174470
    Availability:
    Ships Same Business Day
    Weight:
    0.38 LBS
    PRODUCT NAME:
    GASKET
    THICKNESS IMPERIAL:
    0,062'
    THICKNESS METRIC:
    1.60 MM
    MATERIAL:
    PAPER
    RIDING STYLE:
    STREET
    THICKNESS:
    1,60 MM (0,062')
    TYPE:
    ROCKER COVER
    UNITS:
    10 PACK
    $27.50
    Qty in Cart: 0
    Quantity:
    Price:
    $27.50
    Subtotal:
  • JAMES GASKET Oil Seal for Supernut 35211-85-DL

    JAMES GASKET Oil Seal for Supernut 35211-85-DL

    JAMES GASKET

    $24.70
    Transmission fluid leaks compromise performance and accelerate internal wear—a quality oil seal is your first line of defense. The JAMES GASKET Oil Seal for Supernut is engineered to maintain a reliable barrier against fluid loss, ensuring consistent...
    DS174458
    SKU:
    DS174458
    Availability:
    Ships Same Business Day
    Weight:
    0.13 LBS
    STYLE:
    4-SPEED
    PRODUCT NAME:
    SEAL
    TYPE:
    SUPER NUT
    RIDING STYLE:
    STREET
    UNITS:
    5 PACK
    $24.70
    Qty in Cart: 0
    Quantity:
    Price:
    $24.70
    Subtotal:
  • JAMES GASKET Derby Cover Gasket Silicon - Big Twin 25416-70-X

    JAMES GASKET Derby Cover Gasket Silicon - Big Twin 25416-70-X

    JAMES GASKET

    $55.40
    A leaking derby cover gasket will compromise your engine's appearance and allow oil seepage that invites corrosion and debris accumulation. The James Gasket Derby Cover Gasket in silicon delivers a reliable, long-lasting seal engineered to prevent these...
    DS174457
    SKU:
    DS174457
    Availability:
    Ships Same Business Day
    Weight:
    0.13 LBS
    MATERIAL:
    SILICONE
    UNITS:
    10 PACK
    FEATURES:
    BEADED
    RIDING STYLE:
    STREET
    STYLE:
    PRIMARY
    THICKNESS IMPERIAL:
    0,062'
    THICKNESS METRIC:
    1.60 MM
    TYPE:
    DERBY COVER
    MATERIAL:
    PAPER
    PRODUCT NAME:
    GASKET
    THICKNESS:
    1,60 MM (0,062')
    $55.40
    Qty in Cart: 0
    Quantity:
    Price:
    $55.40
    Subtotal:
  • JAMES GASKET Trans Mainshaft Seal Kit - 4 Speed 37741-67-K

    JAMES GASKET Trans Mainshaft Seal Kit - 4 Speed 37741-67-K

    JAMES GASKET

    $24.95
    Transmission seal degradation is one of the most common sources of fluid leaks on Big Twin engines, leading to costly damage if left unaddressed. The JAMES GASKET Trans Mainshaft Seal Kit gives you OEM-quality sealing with the reliability of U.S...
    DS174456
    SKU:
    DS174456
    Availability:
    Ships Same Business Day
    Weight:
    0.13 LBS
    APPLICATION:
    TRANSMISSION
    STYLE:
    4-SPEED
    PRODUCT NAME:
    SEAL KIT
    UNITS:
    KIT
    RIDING STYLE:
    STREET
    $24.95
    Qty in Cart: 0
    Quantity:
    Price:
    $24.95
    Subtotal:
  • JAMES GASKET Main Drive Gear Double Lip Seal 37741-82DL

    JAMES GASKET Main Drive Gear Double Lip Seal 37741-82DL

    JAMES GASKET

    $13.95
    A worn main drive gear seal is an open invitation to oil leakage, reduced efficiency, and potential drivetrain damage. The JAMES GASKET Double Lip Seal 37741-82DL delivers OEM-grade sealing performance with dual-lip construction that actively wipes...
    DS174455
    SKU:
    DS174455
    Availability:
    Ships Same Business Day
    Weight:
    0.04 LBS
    APPLICATION:
    MAIN DRIVE GEAR
    PRODUCT NAME:
    SEAL
    RIDING STYLE:
    STREET
    UNITS:
    EACH
    $13.95
    Qty in Cart: 0
    Quantity:
    Price:
    $13.95
    Subtotal:
  • JAMES GASKET Shift Fork Shaft - Big Twin 34036-80

    JAMES GASKET Shift Fork Shaft - Big Twin 34036-80

    JAMES GASKET

    $7.80
    A worn or damaged shift fork shaft compromises your transmission's reliability and shifts—exactly what you can't afford during competition or spirited riding. The JAMES GASKET Shift Fork Shaft is engineered to OEM specifications with quality washers...
    DS174454
    SKU:
    DS174454
    Availability:
    Ships Same Business Day
    Weight:
    0.02 LBS
    PRODUCT NAME:
    WASHER
    RIDING STYLE:
    STREET
    TYPE:
    SHIFTER SHAFT
    UNITS:
    10 PACK
    Qty in Cart: 0
    Quantity:
    Price:
    $7.80
    Subtotal:
  • Total: items /

Adding your products to cart

Big Power, Nice Sound!

Picked up a Pro Circuit pipe and silencer for my YZ125 it’s a game changer. The power feels way better and the sound is awesome.

Tyler D. - 06/12

Perfect Fit

First time ordering here and dang y’all knocked it outta the park! The wheels fit my Ranger UTV perfect, and I’ll definitely be back for more 5 stars all day!

Sarah L. - 08/24

Fast Shipping!!

Ordered on a Monday, and it was on my doorstep by Wednesday! Super impressed with how fast the shipping was.

Jason P. - 09/13

Helps keep cool, works great!

Bought the dual pass Allstar radiator for my build, and it’s been solid. Keeps the engine running cool even on the hottest days no complaints here!

Jake M. - 05/21

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