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
-
On Sale
ATHENA Top End Gasket Kit - Kawasaki P400250600030
ATHENA
MSRP: $47.95Now: $43.00Was: $47.95Specifically designed for the pro, semi-pro and amateur rider who freshens up their engine prior to a race or during midseason. Gives the rider a choice of using standard gas with stock compression, or race gas with a higher compression. Kits do not...09343166- SKU:
- 09343166
- Availability:
- Ships Same Business Day
- Weight:
- 0.20 LBS
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- GASKET KIT
- TYPE:
- TOP END
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $47.95Now: $43.00Was: $47.95 -
On Sale
ATHENA Top End Gasket Kit - KTM P400270600072
ATHENA
MSRP: $147.95Now: $133.00Was: $147.95Specifically designed for the pro, semi-pro and amateur rider who freshens up their engine prior to a race or during midseason. Gives the rider a choice of using standard gas with stock compression, or race gas with a higher compression. Kits do not...09343169- SKU:
- 09343169
- Availability:
- Ships Same Business Day
- Weight:
- 0.26 LBS
- PRODUCT NAME:
- GASKET KIT
- UNITS:
- KIT
- ENGINE TYPE:
- 4-STROKE
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- TOP END
MSRP: $147.95Now: $133.00Was: $147.95 -
On Sale
ATHENA Complete Gasket Kit - Yamaha P400485900188
ATHENA
MSRP: $182.95Now: $165.00Was: $182.95Superior-quality gasket sets from Athena, Head gaskets feature rubber-coated spring steel construction, Soft steel base gaskets are rubber coated, Steel core materials feature high springback and superior tensile strength, Revolutionary transparent...09343174- SKU:
- 09343174
- Availability:
- Ships Same Business Day
- Weight:
- 0.52 LBS
- ENGINE TYPE:
- 4-STROKE
- PRODUCT NAME:
- GASKET KIT
- TYPE:
- COMPLETE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $182.95Now: $165.00Was: $182.95 -
On Sale
ATHENA Water Pump Gasket Kit - Suzuki P400510470005
ATHENA
MSRP: $42.95Now: $39.00Was: $42.95Include water pump gasket, clutch cover gasket, water pump shaft oil seals and washers, Kit contents will vary slightly based on application, Kits do not contain replacement bearings09345162- SKU:
- 09345162
- Availability:
- Ships Same Business Day
- Weight:
- 0.25 LBS
- TYPE:
- WATER PUMP
- UNITS:
- KIT
- RIDING STYLE:
- OFF-ROAD
- PRODUCT NAME:
- GASKET KIT
MSRP: $42.95Now: $39.00Was: $42.95 -
On Sale
ATHENA Cylinder Kit - YZ125 - 58mm P400485100030
ATHENA
MSRP: $1,223.95Now: $1,102.00Was: $1,223.95Kits include aluminum cylinder with nickel-carbide coating designed with larger water jackets, Forged piston with molybdenum coating, Special gasket kit, Easy-to-follow step-by-step installation instructions, All are bolt-on; no machining required09310146- SKU:
- 09310146
- Availability:
- Ships Same Business Day
- Weight:
- 5.16 LBS
- CYLINDER BORE COATING:
- NICKEL-CARBIDE
- DISPLACEMENT:
- 144 CC
- ENGINE TYPE:
- 2-STROKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE METRIC:
- 58.00 MM
- MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- CYLINDER KIT
- STYLE:
- BIG BORE
MSRP: $1,223.95Now: $1,102.00Was: $1,223.95 -
On Sale
ATHENA Piston Kit - Yamaha/Malaguti S4C04760006A
ATHENA
MSRP: $61.95Now: $56.00Was: $61.95Piston kits include piston, rings, wrist pin, and circlips09100581- SKU:
- 09100581
- Availability:
- Ships Same Business Day
- Weight:
- 0.24 LBS
- BORE - OVERSIZE:
- STANDARD
- BORE - OVERSIZE METRIC:
- STANDARD
- RIDING STYLE:
- STREET
- BORE SIZE METRIC:
- 47.66 MM
- PISTON MATERIAL:
- ALUMINUM
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
MSRP: $61.95Now: $56.00Was: $61.95 -
On Sale
ATHENA Piston Kit S4F06640018A
ATHENA
MSRP: $187.95Now: $169.00Was: $187.95Two-stroke pistons are made from 4032 silicium, Four-stroke pistons are made from 2618 silicium - the same material used to produce Formula 1 pistons, Both include 3% copper in materials for better heat resistance, All pistons are forged using a...09100627- SKU:
- 09100627
- Availability:
- Ships Same Business Day
- Weight:
- 0.67 LBS
- BORE SIZE METRIC:
- 66.34 MM
- COMPRESSION RATIO IMPERIAL:
- STOCK
- DISPLACEMENT:
- 250 CC
- PRODUCT NAME:
- PISTON KIT
- RIDING STYLE:
- STREET
- TYPE:
- A
- ENGINE TYPE:
- 2-STROKE
- PISTON HEAD SHAPE:
- DOMED
- PISTON MATERIAL:
- 4032 ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
MSRP: $187.95Now: $169.00Was: $187.95 -
On Sale
ATHENA Piston Kit S4F06640019A
ATHENA
MSRP: $173.95Now: $157.00Was: $173.95Two-stroke pistons are made from 4032 silicium, Four-stroke pistons are made from 2618 silicium - the same material used to produce Formula 1 pistons, Both include 3% copper in materials for better heat resistance, All pistons are forged using a...09100641- SKU:
- 09100641
- Availability:
- Ships Same Business Day
- Weight:
- 0.69 LBS
- BORE SIZE METRIC:
- 66.34 MM
- COMPRESSION RATIO IMPERIAL:
- STOCK
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
- PISTON HEAD SHAPE:
- DOMED
- PISTON MATERIAL:
- 4032 ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- ENGINE TYPE:
- 2-STROKE
- DISPLACEMENT:
- 249 CC
- TYPE:
- A
MSRP: $173.95Now: $157.00Was: $173.95Qty in Cart: 0Quantity:Price:MSRP: $173.95Now: $157.00Was: $173.95Subtotal: -
On Sale
ATHENA Piston Kit S5F08200001A
ATHENA
MSRP: $245.95Now: $221.00Was: $245.95Includes rings, clips and pin, Easy-to-follow step-by-step installation instructions09100646- SKU:
- 09100646
- Availability:
- Ships Same Business Day
- Weight:
- 0.56 LBS
- PISTON DIAMETER METRIC:
- 81.95 MM
- STYLE:
- BIG BORE
- PISTON SIZE METRIC:
- STANDARD SIZE A
- PRODUCT NAME:
- PISTON
- COMPRESSION RATIO IMPERIAL:
- 13.1:1
- ENGINE TYPE:
- 4-STROKE
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
MSRP: $245.95Now: $221.00Was: $245.95 -
On Sale
ATHENA Piston Kit S4C05800001A
ATHENA
MSRP: $242.95Now: $219.00Was: $242.95Includes rings, clips and pin, Easy-to-follow step-by-step installation instructions09100648- SKU:
- 09100648
- Availability:
- Ships Same Business Day
- Weight:
- 0.42 LBS
- STYLE:
- BIG BORE
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 57.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- COMPRESSION RATIO IMPERIAL:
- 14.0:1
- PRODUCT NAME:
- PISTON
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
MSRP: $242.95Now: $219.00Was: $242.95 -
On Sale
ATHENA Piston Kit S4C04850001B
ATHENA
MSRP: $89.95Now: $81.00Was: $89.95Two-stroke pistons are made from 4032 silicium, Four-stroke pistons are made from 2618 silicium - the same material used to produce Formula 1 pistons, Both include 3% copper in materials for better heat resistance, All pistons are forged using a...09101418- SKU:
- 09101418
- Availability:
- Ships Same Business Day
- Weight:
- 0.32 LBS
- DISPLACEMENT:
- 85 CC
- ENGINE TYPE:
- 2-STROKE
- PISTON HEAD SHAPE:
- DOMED
- PISTON MATERIAL:
- 4032 ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- KIT
- BORE SIZE METRIC:
- 48.46 MM
- COMPRESSION RATIO IMPERIAL:
- STOCK
- PRODUCT NAME:
- PISTON KIT
- TYPE:
- B
MSRP: $89.95Now: $81.00Was: $89.95 -
On Sale
ATHENA Piston S4C05400016A
ATHENA
MSRP: $185.95Now: $167.00Was: $185.95Includes rings, clips and pin, Easy-to-follow step-by-step installation instructions09100669- SKU:
- 09100669
- Availability:
- Ships Same Business Day
- Weight:
- 0.39 LBS
- PRODUCT NAME:
- PISTON
- UNITS:
- EACH
- COMPRESSION RATIO IMPERIAL:
- 14.8:1
- ENGINE TYPE:
- 2-STROKE
- PISTON DIAMETER METRIC:
- 53.94 MM
- PISTON SIZE METRIC:
- STANDARD SIZE A
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- STANDARD BORE
MSRP: $185.95Now: $167.00Was: $185.95 -
On Sale
ATHENA Piston Kit S4C05000002A
ATHENA
MSRP: $100.95Now: $91.00Was: $100.95Includes rings, clips and pin, Easy-to-follow step-by-step installation instructions09101328- SKU:
- 09101328
- Availability:
- Ships Same Business Day
- Weight:
- 0.29 LBS
- PISTON DIAMETER METRIC:
- 49.95 MM
- PRODUCT NAME:
- PISTON
- COMPRESSION RATIO IMPERIAL:
- 15.0:1
- ENGINE TYPE:
- 2-STROKE
- UNITS:
- EACH
- RIDING STYLE:
- OFF-ROAD
- STYLE:
- BIG BORE
- PISTON SIZE METRIC:
- STANDARD SIZE A
MSRP: $100.95Now: $91.00Was: $100.95 -
On Sale
ATHENA Piston Kit S4F08200005A
ATHENA
MSRP: $277.95Now: $250.00Was: $277.95Includes rings, clips and pin, Easy-to-follow step-by-step installation instructions09103414- SKU:
- 09103414
- Availability:
- Ships Same Business Day
- Weight:
- 0.74 LBS
- PISTON SIZE METRIC:
- STANDARD SIZE A
- ENGINE TYPE:
- 4-STROKE
- PISTON DIAMETER METRIC:
- 81.95 MM
- PRODUCT NAME:
- PISTON
- RIDING STYLE:
- OFF-ROAD
- UNITS:
- EACH
- COMPRESSION RATIO IMPERIAL:
- 16.0:1
- RIDING STYLE:
- STREET
- STYLE:
- BIG BORE
MSRP: $277.95Now: $250.00Was: $277.95Qty in Cart: 0Quantity:Price:MSRP: $277.95Now: $250.00Was: $277.95Subtotal: -
On Sale
ATHENA Piston Kit S4F05400017A
ATHENA
MSRP: $130.95Now: $118.00Was: $130.95Two-stroke pistons are made from 4032 silicium, Four-stroke pistons are made from 2618 silicium - the same material used to produce Formula 1 pistons, Both include 3% copper in materials for better heat resistance, All pistons are forged using a...09103891- SKU:
- 09103891
- Availability:
- Ships Same Business Day
- Weight:
- 0.55 LBS
- DISPLACEMENT:
- 124 CC
- ENGINE TYPE:
- 2-STROKE
- PISTON MATERIAL:
- 4032 ALUMINUM ALLOY
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- A
- BORE SIZE METRIC:
- 53.95 MM
- PISTON HEAD SHAPE:
- FLAT TOP
- COMPRESSION RATIO IMPERIAL:
- STOCK
- PRODUCT NAME:
- PISTON KIT
- UNITS:
- KIT
MSRP: $130.95Now: $118.00Was: $130.95Qty in Cart: 0Quantity:Price:MSRP: $130.95Now: $118.00Was: $130.95Subtotal: -
On Sale
ATHENA Complete Gasket Kit - Kawasaki P400250850030
ATHENA
MSRP: $70.95Now: $64.00Was: $70.95Superior-quality gasket sets from Athena, Head gaskets feature rubber-coated spring steel construction, Soft steel base gaskets are rubber coated, Steel core materials feature high springback and superior tensile strength, Revolutionary transparent...09341520- SKU:
- 09341520
- Availability:
- Ships Same Business Day
- Weight:
- 0.21 LBS
- PRODUCT NAME:
- GASKET KIT
- ENGINE TYPE:
- -
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
MSRP: $70.95Now: $64.00Was: $70.95 -
On Sale
ATHENA Gasket Kit - KX65 - 50 mm P400250160007
ATHENA
MSRP: $46.95Now: $42.00Was: $46.95Kits include aluminum cylinder with nickel-carbide coating designed with larger water jackets, Forged piston with molybdenum coating, Special gasket kit, Easy-to-follow step-by-step installation instructions, All are bolt-on; no machining required09341533- SKU:
- 09341533
- Availability:
- Ships Same Business Day
- Weight:
- 0.07 LBS
- BORE SIZE METRIC:
- 50.00 MM
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE:
- 50,00 MM
- PRODUCT NAME:
- GASKET KIT
- UNITS:
- KIT
- TYPE:
- TOP END
MSRP: $46.95Now: $42.00Was: $46.95 -
On Sale
ATHENA Gasket Kit - RMZ450 - 100 mm P400510160006
ATHENA
MSRP: $105.95Now: $95.00Was: $105.95Kits include aluminum cylinder with nickel-carbide coating designed with larger water jackets, Forged piston with molybdenum coating, Special gasket kit, Easy-to-follow step-by-step installation instructions, All are bolt-on; no machining required09341538- SKU:
- 09341538
- Availability:
- Ships Same Business Day
- Weight:
- 0.17 LBS
- PRODUCT NAME:
- GASKET KIT
- RIDING STYLE:
- OFF-ROAD
- BORE SIZE METRIC:
- 100.00 MM
- UNITS:
- KIT
- BORE SIZE:
- 100,00 MM
- TYPE:
- TOP END
MSRP: $105.95Now: $95.00Was: $105.95Qty in Cart: 0Quantity:Price:MSRP: $105.95Now: $95.00Was: $105.95Subtotal: -
On Sale
ATHENA Complete Gasket Kit - Kawasaki P400250850011
ATHENA
MSRP: $58.95Now: $53.00Was: $58.95Superior-quality gasket sets from Athena, Head gaskets feature rubber-coated spring steel construction, Soft steel base gaskets are rubber coated, Steel core materials feature high springback and superior tensile strength, Revolutionary transparent...09340204- SKU:
- 09340204
- Availability:
- Ships Same Business Day
- Weight:
- 0.50 LBS
- RIDING STYLE:
- OFF-ROAD
- TYPE:
- COMPLETE
- UNITS:
- KIT
- ENGINE TYPE:
- -
- PRODUCT NAME:
- GASKET KIT
MSRP: $58.95Now: $53.00Was: $58.95 -
On Sale
ATHENA Top End Gasket Kit P400250600011
ATHENA
MSRP: $41.95Now: $38.00Was: $41.95Specifically designed for the pro, semi-pro and amateur rider who freshens up their engine prior to a race or during midseason. Gives the rider a choice of using standard gas with stock compression, or race gas with a higher compression. Kits do not...09340206- SKU:
- 09340206
- Availability:
- Ships Same Business Day
- Weight:
- 0.19 LBS
- TYPE:
- TOP END
- PRODUCT NAME:
- GASKET KIT
- UNITS:
- KIT
- MATERIAL:
- RUBBER
- RIDING STYLE:
- OFF-ROAD
MSRP: $41.95Now: $38.00Was: $41.95
