Dirt Bike Engine
4752 parts
Pistons, top-end kits, gaskets, cylinders, valves, bearings and seals from Vertex, ProX, Wossner, Athena, Cometic, WSM, Boyesen and Moose Offroad. Everything you need for a fresh top end, a full rebuild or a little more power. Shop all dirt bike parts.
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Cylinder Works - 21009-K01 - Cylinder Kit - Big Bore - 72.00 mm - Yamaha
Cylinder Works
$1,255.75Cylinder Works - 09311163 - Cylinder Kit - Big Bore - 72.00 mm - YamahaFeaturesCylinders have a nickel silicon carbide cylinder sleeveLook virtually identical to OEM cylindersKit includes cylinder,...$1,255.75 -
Cometic - C3813 - Top End Gasket Kit - 97 mm - Fits 2023-2025 Yamaha YZ450F
Cometic
$87.95Cometic - 09347863 - Top End Gasket Kit - 97 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$87.95 -
Cometic - C7682 - Top End Gasket Kit - 47 mm - Kawasaki/Suzuki - Fits 2000-2025 Kawasaki KX65, 2003-2008 Suzuki RM65
Cometic
$28.95Cometic - 09347866 - Top End Gasket Kit - 47 mm - Kawasaki/SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better...$28.95 -
Cometic - C3806 - Top End Gasket Kit - 96 mm - Fits 2021-2023 Kawasaki KX450/SR/X
Cometic
$88.95Cometic - 09347861 - Top End Gasket Kit - 96 mm - KawasakiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$88.95 -
Cometic - C3779-EST - Top End Gasket Kit - 90 mm - KTM
Cometic
$74.95Cometic - 09347853 - Top End Gasket Kit - 90 mm - KTMFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring seal...$74.95 -
Cometic - C3406-EST - Top End Gasket Kit - 77 mm - Fits 2010-2025 Suzuki RM-Z250
Cometic
$69.95Cometic - 09347832 - Top End Gasket Kit - 77 mm - SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$69.95 -
Cometic - C3695 - Top End Gasket Kit - 77 mm Stock - Fits Yamaha 2020-2025 WR250F, 2019-2025 YZ250F/X
Cometic
$79.95Cometic - 09347847 - Top End Gasket Kit - 77 mm Stock - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston...$79.95 -
Cometic - C3623 - Top End Gasket Kit - KTM/Husqvarna/Gas Gas
Cometic
$46.95Cometic - 09347804 - Top End Gasket Kit - KTM/Husqvarna/Gas GasFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston...$46.95 -
Cometic - C3234-EST - Top End Gasket Kit - 99 mm - Fits 2010-2019 Suzuki RMX450Z
Cometic
$89.95Cometic - 09347828 - Top End Gasket Kit - 99 mm - SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$89.95 -
Cometic - C3542 - Top End Gasket Kit - 52.5 mm Stock - Fits 2014-2021 Kawasaki KX100
Cometic
$31.95Cometic - 09347840 - Top End Gasket Kit - 52.5 mm Stock - KawasakiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better...$31.95 -
Cometic - C3604-EST - Top End Gasket Kit - 95 mm - KTM/Husqvarna/Gas Gas - Multiple Gas Gas/Husqvarna/KTM Models
Cometic
$74.95Cometic - 09347807 - Top End Gasket Kit - 95 mm - KTM/Husqvarna/Gas GasFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and...$74.95 -
Cometic - C3233-EST - Top End Gasket Kit - 97 mm Stock - Fits 2008-2025 Suzuki RM-Z450
Cometic
$89.95Cometic - 09347827 - Top End Gasket Kit - 97 mm Stock - SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston...$89.95 -
Cometic - C3215 - Top End Gasket Kit - Fits 2022-2025 Yamaha YZ125/X
Cometic
$44.95Cometic - 09347826 - Top End Gasket Kit - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring seal for...$44.95 -
Cometic - C3636 - Top End Gasket Kit - KTM/Husqvarna/Gas Gas
Cometic
$47.95Cometic - 09347801 - Top End Gasket Kit - KTM/Husqvarna/Gas GasFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston...$47.95 -
Cometic - C3811 - Top End Gasket Kit - KTM/Husqvarna/Gas Gas
Cometic
$79.95Cometic - 09347803 - Top End Gasket Kit - KTM/Husqvarna/Gas GasFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston...$79.95 -
Cometic - C3808 - Top End Gasket Kit - Gas Gas/KTM/Husqvarna
Cometic
$92.95Cometic - 09347802 - Top End Gasket Kit - Gas Gas/KTM/HusqvarnaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston...$92.95 -
Cometic - C3733 - Top End Gasket Kit - 96 mm - Fits Honda 2019-2020 CRF450R/RWE/RX, 2021-2025 CRF450RL
Cometic
$85.95Cometic - 09347850 - Top End Gasket Kit - 96 mm - HondaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$85.95 -
Cometic - C3694 - Top End Gasket/O-Ring Cylinder Head Gasket Kit - Fits 2018-2023 Yamaha YZ65
Cometic
$39.95Cometic - 09351299 - Top End Gasket/O-Ring Cylinder Head Gasket Kit - YamahaFeaturesSpecsTypeTop End$39.95 -
Cometic - C3630 - Top End Gasket Kit - 97 mm - Fits Yamaha 2019-2020 WR450F, 2018-2019 YZ450F, 2019-2020 YZ450FX
Cometic
$53.95Cometic - 09347845 - Top End Gasket Kit - 97 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$53.95 -
Cometic - C3766 - Top End Gasket Kit - 80 mm - Yamaha
Cometic
$79.95Cometic - 09347852 - Top End Gasket Kit - 80 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$79.95 -
Cometic - C3540-EST - Top End Gasket Kit - 97 mm - Fits Yamaha 2016-2018 WR450F, 2014-2017 YZ450F, 2016-2018 YZ450FX
Cometic
$68.95Cometic - 09347839 - Top End Gasket Kit - 97 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$68.95 -
Cometic - C3787 - Top End Gasket Kit - 79 mm - Fits 2019-2020 Kawasaki KX250
Cometic
$84.95Cometic - 09347856 - Top End Gasket Kit - 79 mm - KawasakiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$84.95 -
Cometic - C3735 - Top End Gasket Kit - 82 mm - Honda
Cometic
$67.95Cometic - 09347851 - Top End Gasket Kit - 82 mm - HondaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$67.95 -
Cometic - C3731 - Top End Gasket Kit/O-Ring Cylinder Head Gasket - Fits 2019-2023 Yamaha YZ65
Cometic
$39.95Cometic - 09347849 - Top End Gasket Kit/O-Ring Cylinder Head Gasket - YamahaFeaturesMaterials will vary depending on what is correct and engineered for specified applicationPurchase a top and a...$39.95 -
Cometic - C3696 - Top End Gasket Kit - 96 mm Stock - Fits 2019-2020 Kawasaki KX450
Cometic
$85.95Cometic - 09347848 - Top End Gasket Kit - 96 mm Stock - KawasakiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better...$85.95 -
Cometic - C3605-EST - Top End Gasket Kit - 88 mm - Fits KTM 2015-2018 350 SX-F, 2015-2018 350 XC-F
Cometic
$74.95Cometic - 09347843 - Top End Gasket Kit - 88 mm - KTMFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring seal...$74.95 -
Cometic - C3410-EST - Top End Gasket Kit - 84 mm - Suzuki
Cometic
$69.95Cometic - 09347837 - Top End Gasket Kit - 84 mm - SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$69.95 -
Cometic - C3543 - Top End Gasket Kit - 54.5 mm - Fits 2022-2025 Kawasaki KX112
Cometic
$31.95Cometic - 09347841 - Top End Gasket Kit - 54.5 mm - KawasakiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston...$31.95 -
Cometic - C3549-EST - Top End Gasket Kit - 77 mm - Fits Yamaha 2014-2019 WR250F, 2014-2018 YZ250F
Cometic
$74.95Cometic - 09347842 - Top End Gasket Kit - 77 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$74.95 -
Cometic - C3407-EST - Top End Gasket Kit - 79 mm - Suzuki
Cometic
$69.95Cometic - 09347833 - Top End Gasket Kit - 79 mm - SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$69.95 -
Cometic - C3408-EST - Top End Gasket Kit - 80 mm - Suzuki
Cometic
$69.95Cometic - 09347834 - Top End Gasket Kit - 80 mm - SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$69.95 -
Cometic - C3595-EST - Top End Gasket Kit - 79 mm - KTM/Husqvarna/Gas Gas - Multiple Gas Gas/Husqvarna/KTM Models
Cometic
$87.95Cometic - 09347806 - Top End Gasket Kit - 79 mm - KTM/Husqvarna/Gas GasFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and...$87.95 -
Cometic - C3171-EST - Top End Gasket Kit - 68 mm - Honda
Cometic
$63.95Cometic - 09347824 - Top End Gasket Kit - 68 mm - HondaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$63.95 -
Cometic - C3235-EST - Top End Gasket Kit - 101 mm - Suzuki
Cometic
$89.95Cometic - 09347831 - Top End Gasket Kit - 101 mm - SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$89.95 -
Boyesen - CC-41CO - Clutch Cover - Orange - KTM/Husqvarna - Fits KTM 2023-2025 125 SX, 2023-2025 125 XC, 2025 150 SX, 2024-2025 150 XC-W
Boyesen
$105.95Boyesen - 09402232 - Clutch Cover - Orange - KTM/HusqvarnaFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$105.95 -
Boyesen - CC-41CL - Clutch Cover - Blue - KTM/Husqvarna - Fits KTM 2023-2025 125 SX, 2023-2025 125 XC, 2025 150 SX, 2024-2025 150 XC-W
Boyesen
$105.95Boyesen - 09402233 - Clutch Cover - Blue - KTM/HusqvarnaFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$105.95 -
La Sleeve - YA814 - Cylinder Sleeve - 95.00 mm - Yamaha
LA Sleeve
MSRP: $146.95$131.95La Sleeve - YA814 - Cylinder Sleeve - 95.00 mm - YamahaFeaturesCenterless grinding of the outside diameters provides for perfect roundnessExact size is controlled by rigid inspection of one-half...MSRP: $146.95$131.95 -
La Sleeve - H5293 - Cylinder Sleeve - 85.00 mm - Honda
LA Sleeve
MSRP: $128.95$111.95La Sleeve - H5293 - Cylinder Sleeve - 85.00 mm - HondaFeaturesCenterless grinding of the outside diameters provides for perfect roundnessExact size is controlled by rigid inspection of one-half...MSRP: $128.95$111.95 -
La Sleeve - FL5430 - Cylinder Sleeve - 90.00 mm - Kawasaki | Suzuki
LA Sleeve
MSRP: $128.95$117.95La Sleeve - FL5430 - Cylinder Sleeve - 90.00 mm - Kawasaki | SuzukiFeaturesCenterless grinding of the outside diameters provides for perfect roundnessExact size is controlled by rigid inspection of...MSRP: $128.95$117.95 -
Cometic - C7826 - Top End Gasket Kit - 89 mm - Honda
Cometic
$46.95Cometic - C7826 - Top End Gasket Kit - 89 mm - HondaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring seal...$46.95
Dirt Bike Pistons, Top-End Kits and Engine Rebuild Parts
Every dirt bike engine needs a refresh eventually. Ride long enough and the piston wears, compression drops and the bike just doesn't pull like it used to. Staying on top of top-end maintenance keeps your bike making power and keeps a cheap rebuild from turning into an expensive one.
We carry pistons and complete top-end kits from Vertex, Wossner, ProX and Athena, full gasket sets from Cometic and Athena, plus valves, springs, cam chains, bearings, seals and crank kits for full rebuilds. Boyesen reed valves and engine covers add performance and protection on two-strokes and four-strokes alike.
While the engine is apart, refresh the rest: fresh air filters and carb parts from fuel and intake, oil filters and fluids from oils and chemicals, and repacking or a new pipe from dirt bike exhaust.
Engine parts are specific to make, model, year and sometimes bore size, so check fitment carefully before ordering. If you're not sure what your rebuild needs, send us your bike's details and we'll help put the parts list together.