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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- Price
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MOOSE RACING Piston Kit - 77.00 mm - Kawasaki MPX3062
MOOSE RACING
$386.95When you're pushing your Kawasaki to the limit, stock pistons become your limiting factor. This MOOSE Racing piston kit delivers the strength and reliability needed for sustained high-RPM performance, while the advanced coating technologies and internal...09106515- SKU:
- 09106515
- Availability:
- Ships Same Business Day
- Weight:
- 0.81 LBS
$386.95 -
MOOSE RACING Piston Kit - 77.00 mm - Yamaha MPX1089
MOOSE RACING
$421.95If you're pushing your Yamaha to the limit, your stock piston won't cut it. This MOOSE Racing piston kit delivers the strength, reliability, and reduced friction needed to handle extreme conditions without sacrificing durability. Built with forged...09106517- SKU:
- 09106517
- Availability:
- Ships Same Business Day
- Weight:
- 0.81 LBS
$421.95 -
Rekluse Clutch Cover Gas Gas EC 450F 2025 RMS-385
REKLUSE
$189.00The stock clutch cover on your Gas Gas EC 450F won't hold up to the punishment of serious off-road riding—inadequate oil capacity means marginal cooling under load, and OEM aluminum lacks the impact resistance you need in rocky terrain. The Rekluse...09402039- SKU:
- 09402039
- Availability:
- Ships Same Business Day
- Weight:
- 0.66 LBS
$189.00 -
On Sale
ATHENA Piston Kit with Gaskets - 76.75 mm - CRF250R P5F0768245001A
ATHENA
MSRP: $214.95Now: $193.00Was: $214.95Your CRF250R's performance ceiling is limited by factory piston tolerances and ring friction losses. The ATHENA 76.75 mm piston kit replaces worn internals with precision-engineered components that restore compression, reduce parasitic drag, and deliver...09031700- SKU:
- 09031700
- Availability:
- Ships Same Business Day
- Weight:
- 1.15 LBS
MSRP: $214.95Now: $193.00Was: $214.95 -
On Sale
ATHENA Piston Kit with Gaskets - 76.76 mm - CRF250R P5F0768245001B
ATHENA
MSRP: $214.95Now: $193.00Was: $214.95The ATHENA Piston Kit delivers the reliability you expect from OE specifications with measurably improved durability and performance for your CRF250R. High-silicon aluminum construction combined with CNC precision manufacturing ensures consistent...09031701- SKU:
- 09031701
- Availability:
- Ships Same Business Day
- Weight:
- 1.12 LBS
MSRP: $214.95Now: $193.00Was: $214.95 -
On Sale
ATHENA Piston Kit with Gaskets - 76.96 mm - RMZ250 P5F0770098004B
ATHENA
MSRP: $218.95Now: $197.00Was: $218.95If you're running a RMZ250 and want to restore peak combustion efficiency and ring seal integrity, this OEM-equivalent piston kit delivers the durability of factory parts with measurably better performance characteristics. The high-silicon aluminum alloy...09031709- SKU:
- 09031709
- Availability:
- Ships Same Business Day
- Weight:
- 1.05 LBS
MSRP: $218.95Now: $197.00Was: $218.95 -
On Sale
ATHENA Piston Kit with Gaskets - 76.95 mm - WR/YZ250F P5F0770187009A
ATHENA
MSRP: $234.95Now: $211.00Was: $234.95When your WR/YZ250F demands reliability under extreme conditions, OE pistons hit their limits. The ATHENA Piston Kit delivers the same dependable engineering as factory components while engineering in superior durability and ring seal efficiency—critical...09031712- SKU:
- 09031712
- Availability:
- Ships Same Business Day
- Weight:
- 1.11 LBS
MSRP: $234.95Now: $211.00Was: $234.95 -
On Sale
ATHENA Piston Kit with Gaskets - 76.95 mm - YZ250F P5F0770212009A
ATHENA
MSRP: $217.95Now: $196.00Was: $217.95When you're pushing your YZ250F to its limits, stock pistons become your weak point—compromising power delivery and ring seal integrity under sustained high RPM. The ATHENA Piston Kit delivers the durability and precision of OE engineering with...09031714- SKU:
- 09031714
- Availability:
- Ships Same Business Day
- Weight:
- 1.19 LBS
MSRP: $217.95Now: $196.00Was: $217.95 -
On Sale
ATHENA Piston Kit with Gaskets - 77.96 mm - KX250F P5F0780069003A
ATHENA
MSRP: $231.95Now: $209.00Was: $231.95OEM reliability without the OEM price—this CNC-machined piston kit delivers factory-grade performance for your KX250F with measurably better durability and ring efficiency. The high-silicon aluminum alloy resists wear longer than standard pistons, while...09031718- SKU:
- 09031718
- Availability:
- Ships Same Business Day
- Weight:
- 1.20 LBS
MSRP: $231.95Now: $209.00Was: $231.95 -
On Sale
ATHENA Piston Kit with Gaskets - 77.95 mm - FE250 | 250EXCF/XCFW P5F0780074001A
ATHENA
MSRP: $292.94Now: $264.00Was: $292.94If you're running a KTM 250 EXC-F or 250 EXC-F W, piston wear directly impacts compression, throttle response, and engine longevity. The ATHENA Piston Kit delivers OEM-level reliability with superior material science—meaning you get stronger performance...09031720- SKU:
- 09031720
- Availability:
- Ships Same Business Day
- Weight:
- 1.26 LBS
MSRP: $292.94Now: $264.00Was: $292.94 -
On Sale
ATHENA Piston Kit with Gaskets - 77.96 mm - FE250 | 250EXCF/XCFW P5F0780074001B
ATHENA
MSRP: $292.94Now: $264.00Was: $292.94When you're pushing your 250EXCF or XCFW to its limits, your piston needs to handle extreme combustion pressures without sacrificing reliability. The ATHENA Piston Kit delivers OE-level dependability while offering superior durability and performance...09031721- SKU:
- 09031721
- Availability:
- Ships Same Business Day
- Weight:
- 1.16 LBS
MSRP: $292.94Now: $264.00Was: $292.94 -
On Sale
ATHENA Piston Kit with Gaskets - 77.95 mm - FE250 | 250EXCF P5F0780078001A
ATHENA
MSRP: $240.10Now: $216.00Was: $240.10Whether you're rebuilding a tired top-end or refreshing your FE250's compression, a quality piston kit directly impacts throttle response, fuel efficiency, and engine longevity. ATHENA's CNC-machined pistons combine OE-level reliability with superior...09031722- SKU:
- 09031722
- Availability:
- Ships Same Business Day
- Weight:
- 1.11 LBS
MSRP: $240.10Now: $216.00Was: $240.10 -
On Sale
ATHENA Piston Kit with Gaskets - 77.96 mm - MC250F | FC250 | 250SXF/XCF P5F0780078002A
ATHENA
MSRP: $240.10Now: $216.00Was: $240.10A worn or damaged piston directly impacts engine compression, throttle response, and overall reliability—especially critical in high-demand off-road conditions. The ATHENA Piston Kit restores your MC250F, FC250, or 250SXF/XCF to factory performance...09031724- SKU:
- 09031724
- Availability:
- Ships Same Business Day
- Weight:
- 1.21 LBS
MSRP: $240.10Now: $216.00Was: $240.10 -
On Sale
ATHENA Piston Kit with Gaskets - 77.97 mm - MC250F | FC250 | 250SXF/XCF P5F0780078002B
ATHENA
MSRP: $240.10Now: $216.00Was: $240.10A properly sized piston kit is critical for maintaining engine compression, combustion efficiency, and overall power output on 4-stroke off-road motorcycles. The ATHENA piston kit delivers OEM-level reliability while offering superior durability and ring...09031725- SKU:
- 09031725
- Availability:
- Ships Same Business Day
- Weight:
- 1.26 LBS
MSRP: $240.10Now: $216.00Was: $240.10 -
On Sale
ATHENA Piston Kit with Gaskets - 77.95 mm - EC250F | FE250 | 250EXCF P5F0780093001A
ATHENA
MSRP: $228.95Now: $206.00Was: $228.95Piston failures compromise engine reliability and performance—this ATHENA kit delivers OE-equivalent durability with measurably superior wear resistance. CNC-machined from high-silicon aluminum alloy, it reduces friction across the ring package while...09031726- SKU:
- 09031726
- Availability:
- Ships Same Business Day
- Weight:
- 1.24 LBS
MSRP: $228.95Now: $206.00Was: $228.95 -
On Sale
ATHENA Piston Kit with Gaskets - 78.96 mm - CRF250R P5F0790319002B
ATHENA
MSRP: $212.95Now: $192.00Was: $212.95Your CRF250R's piston is the heart of combustion efficiency—worn or low-quality units rob you of power, throttle response, and engine longevity. The ATHENA Piston Kit restores OEM-level reliability while delivering measurably improved performance through...09031731- SKU:
- 09031731
- Availability:
- Ships Same Business Day
- Weight:
- 1.25 LBS
MSRP: $212.95Now: $192.00Was: $212.95 -
On Sale
ATHENA Piston Kit with Gaskets - 78.95 mm - CRF250R P5F0790319002A
ATHENA
MSRP: $212.95Now: $192.00Was: $212.95A worn or damaged piston directly kills your CRF250R's combustion efficiency, power output, and engine longevity. This ATHENA piston kit restores your bike to factory performance specs with precision-engineered components that handle the demands of...09031730- SKU:
- 09031730
- Availability:
- Ships Same Business Day
- Weight:
- 1.25 LBS
MSRP: $212.95Now: $192.00Was: $212.95 -
MOOSE RACING Water Pump Cover - Black - Gas Gas/Husqvarna I04-5259B
MOOSE RACING
$88.95If you're running a Gas Gas or Husqvarna machine, the factory water pump cover is vulnerable to damage and heat stress during aggressive riding. This MOOSE Racing billet aluminum cover replaces that weak point with a precision-machined component that...09402049- SKU:
- 09402049
- Availability:
- Ships Same Business Day
- Weight:
- 0.10 LBS
$88.95 -
MOOSE RACING Clutch Cylinder Guard - Gas Gas/Husqvarna/KTM 13-1123
MOOSE RACING
$42.95Hydraulic clutch cylinders are vulnerable to impact damage during aggressive riding—a single crash can leave you stranded. This MOOSE RACING guard protects that critical component with CNC-machined aluminum construction while its integrated knockdown bar...09500993- SKU:
- 09500993
- Availability:
- Ships Same Business Day
- Weight:
- 0.31 LBS
$42.95 -
MOOSE RACING Clutch Cylinder Guard - Gas Gas/KTM/Husqvarna 13-1223
MOOSE RACING
$42.95Hydraulic clutch cylinders are vulnerable to impact and chain strikes—damage means downtime and expensive repairs. This CNC-machined guard absorbs hits that would otherwise compromise your clutch system, keeping you on the track or trail. Built for Gas...09500994- SKU:
- 09500994
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
$42.95
