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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On Sale
PROX Piston Kit - 57.94 mm - Husqvarna TE150i | KTM 150EXC TPI 01.6241.A
PROX
MSRP: $139.95Now: $119.00Was: $139.95A worn or damaged piston directly compromises engine compression, throttle response, and overall reliability—especially critical on high-revving 150cc two-stroke engines. The PROX 57.94 mm Piston Kit delivers OEM-equivalent performance with Japanese...09106792- SKU:
- 09106792
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
MSRP: $139.95Now: $119.00Was: $139.95 -
On Sale
PROX Piston Kit - 87.96 mm - Gas Gas | Husqvarna | KTM 01.6353.A
PROX
MSRP: $209.95Now: $195.00Was: $229.73Whether you're rebuilding a top-end after a hard race season or restoring a two-stroke to factory specifications, a precision piston kit is non-negotiable. The PROX 87.96 mm Piston Kit delivers OEM-quality components that restore compression, seal...09106793- SKU:
- 09106793
- Availability:
- Ships Same Business Day
- Weight:
- 0.45 LBS
MSRP: $209.95Now: $195.00Was: $229.73 -
On Sale
PROX Piston Kit - 94.95 mm - Gas Gas | Husqvarna | KTM 01.6434.A
PROX
MSRP: $221.95Now: $183.00Was: $221.95Piston Kit - 94.95 mm - Gas Gas | Husqvarna | KTM Kit includes piston, rings, wrist pin, circlips and instruction sheet, The piston is precision machined on state of the art CNC equipment, Piston rings are made by OEM factories to exact specifications09106794- SKU:
- 09106794
- Availability:
- Ships Same Business Day
- Weight:
- 1.00 LBS
MSRP: $221.95Now: $183.00Was: $221.95Qty in Cart: 0Quantity:Price:MSRP: $221.95Now: $183.00Was: $221.95Subtotal: -
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 components precision-machined to exact tolerances, ensuring...09106795- SKU:
- 09106795
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
MSRP: $221.95Now: $167.00Was: $221.95 -
On Sale
PROX Piston Kit - 94.96 mm - Gas Gas | Husqvarna | KTM 01.6443.A
PROX
MSRP: $214.95Now: $183.00Was: $214.95Piston Kit - 94.96 mm - Gas Gas | Husqvarna | KTM Kit includes piston, rings, wrist pin, circlips and instruction sheet, The piston is precision machined on state of the art CNC equipment, Piston rings are made by OEM factories to exact specifications09106796- SKU:
- 09106796
- Availability:
- Ships Same Business Day
- Weight:
- 0.83 LBS
MSRP: $214.95Now: $183.00Was: $214.95 -
On Sale
PROX Piston Kit - 94.95 mm - Gas Gas | Husqvarna | KTM 01.6513.A
PROX
MSRP: $221.95Now: $183.00Was: $221.95Piston Kit - 94.95 mm - 01.6513.A High-performance piston kit designed for Gas Gas, Husqvarna, and KTM motorcycles. Includes all essential components: piston, rings, wrist pin, circlips, and instruction sheet. Precision machined using...09106797- SKU:
- 09106797
- Availability:
- Ships Same Business Day
- Weight:
- 0.78 LBS
MSRP: $221.95Now: $183.00Was: $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 engineering with precision CNC-machining and high-silicon...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, eliminating the guesswork of sourcing individual...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 to exact specifications, ensuring reliable power...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: $166.95Piston Kit - 66.34 mm - 01.7334.A OEM replacement designed specifically for Sherco 250SE/250SE-R models. Manufactured in Japan for superior quality and reliability. Crafted from high-silicon-content aluminum alloy for enhanced durability. ...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: $166.95Piston Kit - 66.34 mm - Sherco 250SE/250SE-R 01.7337.A Precision-engineered for perfect fit and performance. Manufactured in Japan ensuring high-quality standards. Made from high-silicon-content aluminum alloy for durability. ...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 precision-engineered components that meet or exceed OEM...09106803- SKU:
- 09106803
- Availability:
- Ships Same Business Day
- Weight:
- 0.80 LBS
MSRP: $221.95Now: $170.00Was: $221.95Qty in Cart: 0Quantity:Price:MSRP: $221.95Now: $170.00Was: $221.95Subtotal: -
On Sale
PROX Piston Kit - 87.96 mm - Beta 350RR 01.7351.A
PROX
MSRP: $221.95Now: $178.00Was: $221.95Piston Kit - 87.96 mm - 01.7351.A Precision machined for optimal performance Includes piston, rings, wrist pin, and circlips OEM-quality piston rings made to exact specifications Comprehensive instruction sheet for easy installation ...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: $221.95Piston Kit - 87.96 mm - 01.7355.A High-performance piston kit designed for Beta 350RR. Includes piston, rings, wrist pin, circlips, and detailed instruction sheet. Precision machined using advanced CNC technology for optimal performance. ...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: $221.95Piston Kit - 87.96 mm - Beta 390RR Kit includes piston, rings, wrist pin, circlips and instruction sheet, The piston is precision machined on state of the art CNC equipment, Piston rings are made by OEM factories to exact specifications09106806- 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. The PROX Piston Kit delivers OEM-grade precision at...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 reliability you need for consistent power delivery, whether...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: $216.95Piston Kit - 94.96 mm - Beta 430RR Kit includes piston, rings, wrist pin, circlips and instruction sheet, The piston is precision machined on state of the art CNC equipment, Piston rings are made by OEM factories to exact specifications09106811- 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: $221.95Piston Kit - 99.96 mm - Beta 480RR Kit includes piston, rings, wrist pin, circlips and instruction sheet, The piston is precision machined on state of the art CNC equipment, Piston rings are made by OEM factories to exact specifications09106812- 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: $221.95Piston Kit - 99.95 mm - Beta 498RR/520RR Kit includes piston, rings, wrist pin, circlips and instruction sheet, The piston is precision machined on state of the art CNC equipment, Piston rings are made by OEM factories to exact specifications09106813- SKU:
- 09106813
- Availability:
- Ships Same Business Day
- Weight:
- 0.95 LBS
MSRP: $221.95Now: $183.00Was: $221.95
