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!
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On Sale
KIBBLEWHITE Valve Guide - Exhaust - +0.010" 40-41639
KIBBLEWHITE
MSRP: $22.95Now: $16.00Was: $22.95Exhaust valve guides are critical wear components that endure extreme temperatures and constant thermal cycling—choosing the right material makes the difference between a guide that lasts and one that fails prematurely. This KIBBLEWHITE exhaust valve...09263394- SKU:
- 09263394
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
MSRP: $22.95Now: $16.00Was: $22.95 -
HOT RODS Bottom End Kit - OE Crankshaft Replacement - Polaris HR00106
HOT RODS
$1,591.95A complete bottom-end rebuild demands precision components and comprehensive gasket coverage—this kit eliminates the guesswork by bundling everything you need for a professional crankshaft replacement. Whether you're refreshing a worn engine or preparing...09210890- SKU:
- 09210890
- Availability:
- Ships Same Business Day
- Weight:
- 27.80 LBS
$1,591.95 -
HOT RODS Bottom End Kit - OE Crankshaft Replacement - Polaris HR00107
HOT RODS
$1,591.95A complete bottom-end rebuild demands precision components and comprehensive gasket coverage—this kit eliminates sourcing individual parts and ensures compatibility across all critical sealing surfaces. Whether you're refreshing a worn crankshaft or...09210891- SKU:
- 09210891
- Availability:
- Ships Same Business Day
- Weight:
- 27.90 LBS
$1,591.95 -
HOT RODS Bottom End Kit - OE Crankshaft Replacement - Polaris HR00118
HOT RODS
$1,591.95A bottom-end rebuild requires precision components and complete gasket coverage—cutting corners here compromises engine reliability and longevity. The HOT RODS Bottom End Kit eliminates guesswork by bundling OE-spec main bearings, seals, and a full...09210897- SKU:
- 09210897
- Availability:
- Ships Same Business Day
- Weight:
- 24.30 LBS
$1,591.95 -
Cylinder Works 66.4mm Cylinder for Yamaha YZ250 1999-2025 20009
CYLINDER WORKS
$645.95If you're running a Yamaha YZ250 and want measurable gains in power and torque without engine teardown complexity, a big-bore cylinder is one of the most direct upgrades available. The Cylinder Works 66.4mm delivers the displacement increase your engine...09311078- SKU:
- 09311078
- Availability:
- Ships Same Business Day
- Weight:
- 6.06 LBS
$645.95 -
MOOSE OFFROAD Cam Chain - DID25 x 82 Links MSEHCDID25082
MOOSE OFFROAD
$20.95A worn or damaged cam chain compromises valve timing precision, leading to power loss, poor fuel economy, and potential engine damage. The MOOSE OFFROAD DID25 x 82 Links cam chain delivers OEM-equivalent performance with select steel construction and...09251421- SKU:
- 09251421
- Availability:
- Ships Same Business Day
- Weight:
- 0.26 LBS
$20.95 -
MOOSE OFFROAD Cam Chain - DID25H x 100 Links MSEHCDID25H100
MOOSE OFFROAD
$53.95A worn or damaged cam chain compromises valve timing precision and can lead to catastrophic engine failure—making a quality replacement essential for any rebuild or high-mileage engine refresh. The MOOSE OFFROAD DID25H cam chain delivers OEM-exceeding...09251423- SKU:
- 09251423
- Availability:
- Ships Same Business Day
- Weight:
- 0.31 LBS
$53.95 -
MOOSE OFFROAD Cam Chain - DID25H x 90 Links MSEHCDID25H090
MOOSE OFFROAD
$40.95A worn or damaged cam chain directly compromises valve timing and engine reliability—especially critical in high-performance applications where precision matters. The MOOSE OFFROAD DID25H cam chain delivers OEM-exceeding durability with select steel...09251424- SKU:
- 09251424
- Availability:
- Ships Same Business Day
- Weight:
- 0.26 LBS
$40.95 -
MOOSE OFFROAD Cam Chain - 92RH2015 x 96 Links MSEHC92RH2015096
MOOSE OFFROAD
$50.95A reliable cam chain is fundamental to engine timing precision and longevity—especially in high-performance builds where tolerances matter. The MOOSE OFFROAD 92RH2015 x 96 Links cam chain delivers the durability and strength needed for demanding...09251425- SKU:
- 09251425
- Availability:
- Ships Same Business Day
- Weight:
- 0.51 LBS
$50.95 -
MOOSE OFFROAD Cam Chain - 92RH2005 x 104 Links MSEHC92RH2005104
MOOSE OFFROAD
$44.95A worn or damaged cam chain compromises valve timing precision and can lead to catastrophic engine damage if left unchecked. The MOOSE OFFROAD Cam Chain delivers OEM-equivalent reliability with select steel construction designed to withstand the demands...09251426- SKU:
- 09251426
- Availability:
- Ships Same Business Day
- Weight:
- 0.26 LBS
$44.95 -
MOOSE OFFROAD Cam Chain - 96RH2015 x108 Links MSEHC96RH2015108
MOOSE OFFROAD
$58.95A worn or damaged cam chain compromises valve timing precision and can lead to catastrophic engine failure. The MOOSE OFFROAD Cam Chain 96RH2015 x108 delivers OEM-grade reliability with shot-peened construction and precision solid bushings, ensuring...09251427- SKU:
- 09251427
- Availability:
- Ships Same Business Day
- Weight:
- 0.56 LBS
$58.95 -
MOOSE OFFROAD Cam Chain - 82RH2010 x 118 Links MSEHC82RH2010118
MOOSE OFFROAD
$82.95A worn or damaged cam chain compromises valve timing precision, leading to power loss, increased wear on critical engine components, and potential catastrophic engine failure. The MOOSE OFFROAD Cam Chain 82RH2010 x 118 Links delivers OEM-equivalent...09251428- SKU:
- 09251428
- Availability:
- Ships Same Business Day
- Weight:
- 0.46 LBS
$82.95 -
MOOSE OFFROAD Cam Chain - 92RH2015 x 114 Links MSEHC92RH2015114
MOOSE OFFROAD
$53.95A worn or compromised cam chain directly impacts valve timing accuracy and engine reliability—two non-negotiables for performance and longevity. The MOOSE OFFROAD Cam Chain delivers OEM-exceeding durability with precision engineering, ensuring consistent...09251429- SKU:
- 09251429
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
$53.95 -
MOOSE OFFROAD Cam Chain - 98XRH2015 x 112 Links MSEHC98XRH2015112
MOOSE OFFROAD
$102.95A worn or damaged cam chain compromises valve timing precision and can lead to catastrophic engine failure. The MOOSE OFFROAD Cam Chain 98XRH2015 x 112 Links delivers OEM-equivalent performance with select steel alloys engineered for durability and...09251430- SKU:
- 09251430
- Availability:
- Ships Same Business Day
- Weight:
- 0.56 LBS
$102.95 -
MOOSE OFFROAD Cam Chain - 92RH2010 x 94 Links MSEHC92RH2010094
MOOSE OFFROAD
$35.95A worn or compromised cam chain directly impacts valve timing precision, which cascades into loss of horsepower, efficiency, and overall engine reliability. The MOOSE OFFROAD 92RH2010 x 94 Links cam chain replaces a fatigued OEM unit with select steel...09251432- SKU:
- 09251432
- Availability:
- Ships Same Business Day
- Weight:
- 0.36 LBS
$35.95 -
MOOSE OFFROAD Cam Chain - 82RH2010 x 128 Links MSEHC82RH2010128
MOOSE OFFROAD
$90.95A worn or damaged cam chain compromises valve timing precision, directly impacting engine performance and reliability. The MOOSE OFFROAD Cam Chain delivers OEM-equivalent durability with precision-engineered construction, ensuring consistent valve...09251433- SKU:
- 09251433
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
$90.95 -
MOOSE OFFROAD Cam Chain - 98XRH2010 x 124 Links MSEHC98XRH2010124
MOOSE OFFROAD
$57.95A worn or compromised cam chain directly impacts valve timing precision, which cascades into power loss, rough idle, and potential engine damage. The MOOSE OFFROAD Cam Chain restores OEM-spec reliability with shot-peened solid bushings and select steel...09251434- SKU:
- 09251434
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
$57.95 -
MOOSE OFFROAD Cam Chain - 98XRH2010 x 122 Links MSEHC98XRH2010122
MOOSE OFFROAD
$58.95A worn or damaged cam chain compromises valve timing precision and can lead to catastrophic engine damage if left unchecked. The MOOSE OFFROAD Cam Chain delivers OEM-equivalent reliability with select steel construction designed to handle demanding...09251435- SKU:
- 09251435
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
$58.95 -
MOOSE OFFROAD Cam Chain - 92RH2015 x 174 Links MSEHC92RH2015174
MOOSE OFFROAD
$88.95A worn or damaged cam chain compromises valve timing accuracy, leading to power loss, rough idle, and potential catastrophic engine damage. The MOOSE OFFROAD Cam Chain restores precise timing control with OEM-exceeding durability, keeping your engine...09251436- SKU:
- 09251436
- Availability:
- Ships Same Business Day
- Weight:
- 0.81 LBS
$88.95 -
MOOSE OFFROAD Cam Chain - 6.35 mm x 108 Links MSEHC00114
MOOSE OFFROAD
$74.95A cam chain is critical to your engine's valve timing and overall reliability—and this MOOSE OFFROAD unit delivers OEM-exceeding durability without compromise. Whether you're running a high-mileage rebuild or a fresh engine build, precision-engineered...09251437- SKU:
- 09251437
- Availability:
- Ships Same Business Day
- Weight:
- 0.66 LBS
$74.95
