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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On Sale
PROX Piston Kit - 94.95 mm - Husqvarna FE450 | KTM 450EXC-F 01.6440.A
PROX
MSRP: $221.95Now: $167.00Was: $221.95The piston is the heart of your engine's combustion process, and a worn or damaged unit directly compromises power delivery, fuel efficiency, and reliability. This PROX kit delivers OEM-quality...09106795- SKU:
- 09106795
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
MSRP: $221.95Now: $167.00Was: $221.95 -
On Sale
PROX Piston Kit - 66.34 mm - Beta RR250/Xtrainer 250 01.7313.A
PROX
MSRP: $159.95Now: $136.00Was: $159.95When your Beta RR250 or Xtrainer 250 demands a fresh top-end rebuild, settling for substandard pistons compromises both reliability and performance. This PROX piston kit delivers OEM-quality...09106798- SKU:
- 09106798
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
MSRP: $159.95Now: $136.00Was: $159.95 -
On Sale
PROX Piston Kit - 75.96 mm - Sherco 250SE-F/250SEF-R 01.7314.A
PROX
MSRP: $209.99Now: $178.00Was: $209.99Your Sherco 250SE engine demands precision components that match OEM specifications without compromise. This PROX piston kit delivers CNC-machined accuracy and OEM-spec rings in a complete assembly,...09106799- SKU:
- 09106799
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
MSRP: $209.99Now: $178.00Was: $209.99 -
On Sale
PROX Piston Kit - 83.95 mm - Sherco 300SE-F/300SEF-R 01.7324.A
PROX
MSRP: $221.95Now: $178.00Was: $221.95Your Sherco 300SE-F/300SEF-R demands precision internals that can withstand the demands of high-RPM racing and aggressive trail riding. This PROX piston kit delivers OEM-quality components engineered...09106800- SKU:
- 09106800
- Availability:
- Ships Same Business Day
- Weight:
- 0.40 LBS
MSRP: $221.95Now: $178.00Was: $221.95 -
On Sale
PROX Piston Kit - 66.34 mm - Sherco 250SE/250SE-R 01.7334.A
PROX
MSRP: $166.95Now: $136.00Was: $166.95When your Sherco 250SE/250SE-R's piston begins to show wear, power delivery suffers and reliability becomes uncertain. This PROX piston kit restores your engine to OEM performance standards with...09106801- SKU:
- 09106801
- Availability:
- Ships Same Business Day
- Weight:
- 0.70 LBS
MSRP: $166.95Now: $136.00Was: $166.95 -
On Sale
PROX Piston Kit - 66.34 mm - Sherco 250SE/250SE-R 01.7337.A
PROX
MSRP: $166.95Now: $136.00Was: $166.95When your Sherco 250SE or 250SE-R piston shows wear, compression loss and power degradation follow. This PROX piston kit restores factory performance and reliability with precision engineering,...09106802- SKU:
- 09106802
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
MSRP: $166.95Now: $136.00Was: $166.95 -
On Sale
PROX Piston Kit - 71.94 mm - Sherco 300SE/300SE-R 01.7346.A
PROX
MSRP: $221.95Now: $170.00Was: $221.95A worn or damaged piston directly compromises combustion efficiency, power delivery, and engine longevity in your Sherco 300SE/300SE-R. This PROX piston kit restores factory performance with...09106803- SKU:
- 09106803
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
MSRP: $221.95Now: $170.00Was: $221.95 -
On Sale
PROX Piston Kit - 87.96 mm - Beta 350RR 01.7351.A
PROX
MSRP: $221.95Now: $178.00Was: $221.95Engine wear compromises power delivery and reliability—a quality piston kit restores your Beta 350RR to factory specifications and beyond. This PROX kit delivers OEM-grade precision with a complete...09106804- SKU:
- 09106804
- Availability:
- Ships Same Business Day
- Weight:
- 0.69 LBS
MSRP: $221.95Now: $178.00Was: $221.95 -
On Sale
PROX Piston Kit - 87.96 mm - Beta 350RR 01.7355.A
PROX
MSRP: $221.95Now: $178.00Was: $221.95When your Beta 350RR demands peak performance, a worn or suboptimal piston compromises both power delivery and engine longevity. The PROX Piston Kit delivers precision-engineered components that...09106805- SKU:
- 09106805
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
MSRP: $221.95Now: $178.00Was: $221.95 -
On Sale
PROX Piston Kit - 87.96 mm - Beta 390RR 01.7365.A
PROX
MSRP: $221.95Now: $183.00Was: $221.95A piston kit is the heart of your engine's combustion cycle—worn or damaged pistons directly compromise compression, power output, and engine longevity. The PROX 87.96 mm kit for the Beta 390RR...09106806- SKU:
- 09106806
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
MSRP: $221.95Now: $183.00Was: $221.95 -
On Sale
PROX Piston Kit - 94.95 mm - Beta 400RR 01.7411.A
PROX
MSRP: $216.95Now: $183.00Was: $216.95A worn or damaged piston directly compromises engine compression, throttle response, and reliability—especially critical in a high-revving 400cc dirt bike where every fraction of performance matters...09106808- SKU:
- 09106808
- Availability:
- Ships Same Business Day
- Weight:
- 0.60 LBS
MSRP: $216.95Now: $183.00Was: $216.95 -
On Sale
PROX Piston Kit - 94.95 mm - Beta 450RR 01.7412.A
PROX
MSRP: $221.95Now: $183.00Was: $221.95Your Beta 450RR's engine demands precision at every combustion cycle—and that starts with a piston kit engineered to exact OEM specifications. The PROX 94.95 mm kit delivers the durability and...09106809- SKU:
- 09106809
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
MSRP: $221.95Now: $183.00Was: $221.95 -
On Sale
PROX Piston Kit - 94.96 mm - Beta 430RR 01.7415.A
PROX
MSRP: $216.95Now: $183.00Was: $216.95A worn or damaged piston directly compromises engine compression, throttle response, and overall reliability—especially critical in high-performance 430RR applications where precision tolerances are...09106811- SKU:
- 09106811
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
MSRP: $216.95Now: $183.00Was: $216.95 -
On Sale
PROX Piston Kit - 99.96 mm - Beta 480RR 01.7425.A
PROX
MSRP: $221.95Now: $183.00Was: $221.95A worn or damaged piston directly impacts engine compression, throttle response, and reliability—especially critical in high-revving two-stroke applications like the Beta 480RR. This PROX piston kit...09106812- SKU:
- 09106812
- Availability:
- Ships Same Business Day
- Weight:
- 0.85 LBS
MSRP: $221.95Now: $183.00Was: $221.95 -
On Sale
PROX Piston Kit - 99.95 mm - Beta 498RR/520RR 01.7512.A
PROX
MSRP: $221.95Now: $183.00Was: $221.95The piston is the heart of your engine's combustion cycle, and worn or damaged pistons will kill performance and reliability. This PROX kit gives you OEM-quality components precision-engineered for...09106813- SKU:
- 09106813
- Availability:
- Ships Same Business Day
- Weight:
- 0.95 LBS
MSRP: $221.95Now: $183.00Was: $221.95 -
On Sale
PROX Crankshaft Bearing/Seal Kit - Gas Gas/Husqvarna/KTM 23.CBS63017
PROX
MSRP: $169.95Now: $136.00Was: $169.95A worn crankshaft bearing or degraded seal compromises engine reliability and can lead to catastrophic internal damage. This OEM-specification kit delivers complete bearing and seal replacement,...09240707- SKU:
- 09240707
- Availability:
- Ships Same Business Day
- Weight:
- 1.03 LBS
MSRP: $169.95Now: $136.00Was: $169.95 -
On Sale
ATHENA Piston Kit with Gaskets - 66.34 mm - KTM P4C0664045001A
ATHENA
MSRP: $187.95Now: $161.00Was: $187.95When you're pushing a 2-stroke off-road engine to its limits, piston failure isn't an option. The ATHENA Piston Kit delivers OEM-level reliability with enhanced durability through precision CNC...09031780- SKU:
- 09031780
- Availability:
- Ships Same Business Day
- Weight:
- 1.40 LBS
MSRP: $187.95Now: $161.00Was: $187.95 -
On Sale
ATHENA Piston Kit with Gaskets - 66.34 mm - Yamaha P4F0664267019A
ATHENA
MSRP: $220.95Now: $189.00Was: $220.95A quality piston kit is fundamental to maintaining peak performance and reliability in high-demand 2-stroke engines. The ATHENA Piston Kit delivers OE-equivalent durability while leveraging advanced...09031784- SKU:
- 09031784
- Availability:
- Ships Same Business Day
- Weight:
- 1.30 LBS
MSRP: $220.95Now: $189.00Was: $220.95 -
BOLT Cylinder and Head Nut Universal Kit - 2 Stroke 2STK-HDNUT
BOLT
$14.99Securing your two-stroke top end requires hardware that won't fail under combustion pressure and high RPM loads. This universal kit eliminates the frustration of sourcing individual fasteners by...09501032- SKU:
- 09501032
- Availability:
- Ships Same Business Day
- Weight:
- 0.30 LBS
$14.99 -
Hinson Racing Clutch Cover for 2023-2024 KTM 250 SX-F CA480-2301
HINSON RACING
$179.99The stock clutch cover on your 2023-2024 KTM 250 SX-F CA will struggle under sustained racing conditions, leading to heat buildup and potential clutch degradation. The Hinson Racing Clutch Cover...09402112- SKU:
- 09402112
- Availability:
- Ships Same Business Day
- Weight:
- 0.75 LBS
$179.99
