Dirt Bike Engine
4639 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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Out of stock
Boyesen - CC-38CM - Clutch Cover - Magnesium - Fits Yamaha 2016-2018 WR450F, 2010-2022 YZ450F, 2016-2023 YZ450FX
Boyesen
$95.95Boyesen - 09400972 - Clutch Cover - Magnesium - YamahaFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$95.95 -
Out of stock
Boyesen - SC02AM - Ignition Cover - Magnesium - Honda CR250R
Boyesen
$87.95Boyesen - 09400211 - Ignition Cover - Magnesium - Honda CR250RFeaturesSeals properly, guarding inside of engine from dirt and water and outlasts stock coversBoyesen Factory Covers are cast from the...$87.95 -
Out of stock
Boyesen - CC-46M - Clutch Cover - Magnesium - Husqvarna/KTM - Fits 2014-2017 Husqvarna TC 85, 2006-2017 KTM 85 SX, 2006-2012 KTM 105 SX
Boyesen
$95.95Boyesen - 09400694 - Clutch Cover - Magnesium - Husqvarna/KTMFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a...$95.95 -
Out of stock
Boyesen - CC-44B - Clutch Cover - Black - Husaberg/KTM - Fits 2013 Husqvarna FE 250, 2005-2012 KTM 250 SX-F, 2007-2013 KTM 250 XCF-W
Boyesen
$95.95Boyesen - 09400570 - Clutch Cover - Black - Husaberg/KTMFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$95.95 -
Out of stock
Boyesen - CC-27AM - Clutch Cover - Magnesium - Fits 2007-2024 Suzuki RM-Z250
Boyesen
$95.95Boyesen - 09400683 - Clutch Cover - Magnesium - SuzukiFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$95.95 -
Out of stock
Boyesen - CC-12CB - Clutch Cover - Black - Fits 2005-2007 Kawasaki KX250
Boyesen
$95.95Boyesen - 09400389 - Clutch Cover - Black - KawasakiFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$95.95 -
Out of stock
Boyesen - CC-32AM - Clutch Cover - Magnesium - Fits Yamaha 1999-2025 YZ250, 2016-2025 YZ250X, 1999-2022 YZ250X
Boyesen
$95.95Boyesen - 09400236 - Clutch Cover - Magnesium - YamahaFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$95.95 -
Out of stock
Boyesen - SC-33AB - Ignition Cover - Black - Fits Yamaha 2005-2025 YZ125, 2020-2025 YZ125X
Boyesen
$87.95Boyesen - 09400383 - Ignition Cover - Black - YamahaFeaturesSeals properly, guarding inside of engine from dirt and water and outlasts stock coversBoyesen Factory Covers are cast from the highest...$87.95 -
Out of stock
Boyesen - CC-37B - Clutch Cover - Black - Fits Yamaha 2001-2013 WR250F, 2001-2013 YZ250F
Boyesen
$95.95Boyesen - 09400234 - Clutch Cover - Black - YamahaFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually surfaced for a perfect,...$95.95 -
Out of stock
Boyesen - SC-01AM - Ignition Cover - Magnesium - Honda CR125R
Boyesen
$87.95Boyesen - 09400209 - Ignition Cover - Magnesium - Honda CR125RFeaturesSeals properly, guarding inside of engine from dirt and water and outlasts stock coversBoyesen Factory Covers are cast from the...$87.95 -
Out of stock
Cv4 - CVMS13000 - Valve Spring Shim Kit - Multiple Models
CV4
$6.59Cv4 - 09261165 - Valve Spring Shim KitFeaturesSpecsProduct NameShimMat$6.59 -
Out of stock
Cylinder Works - 11001-G01 - Big Bore Gasket Kit - Honda
Cylinder Works
$66.45Cylinder Works - 09341521 - Big Bore Gasket Kit - HondaFeaturesCylinder kit includes matched Vertex pistons to ensure longevity, performance and reduced engine noiseNickel Silicon Carbide plated for...$66.45 -
Out of stock
Cometic - C7726 - Top End Gasket Kit - 75 mm - Yamaha
Cometic
$35.95Cometic - 09341037 - Top End Gasket Kit - 75 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$35.95 -
Out of stock
Del West - DW-CRF450R-EV02 - Exhaust Valve - Honda CRF450R/X '02-'06 - Fits 2002-2006 Honda CRF450R/X
Del West
$155.95Del West - 09261046 - Exhaust Valve - Honda CRF450R/X '02-'06FeaturesTitanium aluminide valves are designed to meet the most exacting requirementsSpecs$155.95 -
Out of stock
Cylinder Works - 11007-K01 - Cylinder Kit - Big Bore - 80.00 mm - Honda
Cylinder Works
$758.95Cylinder Works - 09310340 - Cylinder Kit - Big Bore - 80.00 mm - HondaFeaturesCylinders have a nickel silicon carbide cylinder sleeveLook virtually identical to OEM cylindersKit includes cylinder,...$758.95 -
Out of stock
Cylinder Works - 30001-K01 - Cylinder Kit - Standard Bore - 77.00 mm - Kawasaki | Suzuki
Cylinder Works
$686.95Cylinder Works - 09310275 - Cylinder Kit - Standard Bore - 77.00 mm - Kawasaki | SuzukiFeaturesCylinder kit includes matched Vertex pistons to ensure longevity, performance and reduced engine...$686.95 -
Out of stock
Cylinder Works - 20002-K01HC - Cylinder Kit - High Compression - 77.00 mm - Yamaha
Cylinder Works
$750.95Cylinder Works - 09310296 - Cylinder Kit - High Compression - 77.00 mm - YamahaFeaturesCylinder kit comes with matched Vertex pistons to ensure longevity, performance and reduced engine noiseKit...$750.95 -
Out of stock
Cylinder Works - 10004-K01HC - Cylinder Kit - High Compression - 66.00 mm - Honda
Cylinder Works
$579.95Cylinder Works - 09310288 - Cylinder Kit - High Compression - 66.00 mm - HondaFeaturesCylinder kit comes with matched Vertex pistons to ensure longevity, performance and reduced engine noiseKit...$579.95 -
Out of stock
Cylinder Works - 20002-K01 - Cylinder Kit - Standard Bore - 77.00 mm - Yamaha
Cylinder Works
$750.95Cylinder Works - 09310278 - Cylinder Kit - Standard Bore - 77.00 mm - YamahaFeaturesCylinder kit includes matched Vertex pistons to ensure longevity, performance and reduced engine noiseNickel...$750.95 -
Out of stock
Cylinder Works - 40003-K01 - Cylinder Kit - Standard Bore - 77.00 mm - Suzuki
Cylinder Works
$704.95Cylinder Works - 09310352 - Cylinder Kit - Standard Bore - 77.00 mm - SuzukiFeaturesCylinder kit includes matched Vertex pistons to ensure longevity, performance and reduced engine noiseNickel...$704.95 -
Out of stock
Cylinder Works - 10006-K01 - Cylinder Kit - Standard Bore - 96.00 mm - Fits 2009-2012 Honda CRF450R
Cylinder Works
$690.95Cylinder Works - 09310273 - Cylinder Kit - Standard Bore - 96.00 mm - HondaFeaturesCylinder kit includes matched Vertex pistons to ensure longevity, performance and reduced engine noiseNickel Silicon...$690.95 -
Out of stock
Cylinder Works - 21005-K01 - Cylinder Kit - Big Bore - 99.00 mm - Yamaha
Cylinder Works
$901.95Cylinder Works - 09310354 - Cylinder Kit - Big Bore - 99.00 mm - YamahaFeaturesCylinders have a nickel silicon carbide cylinder sleeveLook virtually identical to OEM cylindersKit includes cylinder,...$901.95 -
Out of stock
Cylinder Works - 21007-K01 - Cylinder Kit - Big Bore - 52.50 mm - Yamaha
Cylinder Works
$885.95Cylinder Works - 09310346 - Cylinder Kit - Big Bore - 52.50 mm - YamahaFeaturesCylinders have a nickel silicon carbide cylinder sleeveLook virtually identical to OEM cylindersKit includes cylinder,...$885.95 -
Out of stock
Cylinder Works - 11002-K01 - Cylinder Kit - Big Bore - 100.00 mm - Honda
Cylinder Works
$736.95Cylinder Works - 09310119 - Cylinder Kit - Big Bore - 100.00 mm - HondaFeaturesCylinders have a nickel silicon carbide cylinder sleeveLook virtually identical to OEM cylindersKit includes cylinder,...$736.95 -
Out of stock
Cylinder Works - 31004-G01 - Big Bore Gasket Kit - Kawasaki
Cylinder Works
$94.95Cylinder Works - 09341929 - Big Bore Gasket Kit - KawasakiFeaturesCylinder kit includes matched Vertex pistons to ensure longevity, performance and reduced engine noiseNickel Silicon Carbide plated...$94.95 -
Out of stock
Cylinder Works - 40004 - Cylinder - 77.00 mm - Fits Suzuki 2010-2012 RM-Z250, 2013-2015 RM-Z250, 2016-2018 RM-Z250
Cylinder Works
$447.95Cylinder Works - 09310402 - Cylinder - 77.00 mm - SuzukiFeaturesNickel Silicon Carbide plated for long lifeMade in the U.S.A.Big bore cylinders do not require machine work.Replacement Part for OEM...$447.95 -
Out of stock
Cylinder Works - 20005 - Cylinder - 97.00 mm - Yamaha
Cylinder Works
$547.95Cylinder Works - 09310396 - Cylinder - 97.00 mm - YamahaFeaturesNickel Silicon Carbide plated for long lifeMade in the U.S.A.Big bore cylinders do not require machine work.Replacement Part for OEM...$547.95 -
Out of stock
Cometic - C7689 - Top End Gasket Kit - 95 mm - Fits Yamaha 1998-1999 YZ400F, 2000-2002 WR/YZ426F
Cometic
$47.95Cometic - 09340392 - Top End Gasket Kit - 95 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$47.95 -
Out of stock
Boyesen - CCG-42 - Clutch Cover Replacement Gasket - Husaberg/Husqvarna/KTM
Boyesen
$7.00Boyesen - 09341291 - Clutch Cover Replacement Gasket - Husaberg/Husqvarna/KTMFeaturesLightweight factory clutch covers provide years of outstanding protection; guaranteed not to warpIndividually...$7.00 -
Out of stock
Cometic - C7142 - Top End Gasket Kit - 68 mm - Fits 1990-1992 Yamaha DT/WR200
Cometic
$32.95Cometic - 09340369 - Top End Gasket Kit - 68 mm - YamahaFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$32.95 -
Out of stock
Cylinder Works - 40003 - Cylinder - 77.00 mm - Fits 2007-2009 Suzuki RM-Z250
Cylinder Works
$461.95Cylinder Works - 09310401 - Cylinder - 77.00 mm - SuzukiFeaturesNickel Silicon Carbide plated for long lifeMade in the U.S.A.Big bore cylinders do not require machine work.Replacement Part for OEM...$461.95 -
Out of stock
Cylinder Works - 50002 - Cylinder - 76.00 mm - Husaberg | KTM
Cylinder Works
$526.95Cylinder Works - 09310404 - Cylinder - 76.00 mm - Husaberg | KTMFeaturesNickel Silicon Carbide plated for long lifeMade in the U.S.A.Big bore cylinders do not require machine work.Replacement Part...$526.95 -
Out of stock
Boyesen - SCG-42 - Ignition Cover Replacement Gasket - KTM
Boyesen
$5.95Boyesen - 09341290 - Ignition Cover Replacement Gasket - KTMFeaturesSeals properly, guarding inside of engine from dirt and water and outlasts stock coversBoyesen Factory Covers are cast from the...$5.95 -
Out of stock
Cometic - C3267-EST - Top End Gasket Kit - 78 mm - Fits 2009-2016 Kawasaki KX250F
Cometic
$91.95Cometic - 09342414 - Top End Gasket Kit - 78 mm - KawasakiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better piston ring...$91.95 -
Out of stock
Cometic - C3174-EST - Top End Gasket Kit - 77 mm - Kawasaki/Suzuki - Fits 2004-2008 Kawasaki KX250F, 2004-2006 Suzuki RM-Z250
Cometic
$91.95Cometic - 09342432 - Top End Gasket Kit - 77 mm - Kawasaki/SuzukiFeaturesMLS head gaskets promote an even torque load across the gasket sealing surface, providing less bore distortion and better...$91.95 -
Out of stock
Cometic - C3268-EST - Top End Gasket Kit - 96 mm - Fits 2009-2015 Kawasaki KX450F
Cometic
$84.95Cometic - 09342420 - 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...$84.95 -
Out of stock
Cylinder Works - 30004 - Cylinder - 77.00 mm - Fits 2009 Kawasaki KX250F
Cylinder Works
$421.95Cylinder Works - 09310398 - Cylinder - 77.00 mm - KawasakiFeaturesNickel Silicon Carbide plated for long lifeMade in the U.S.A.Big bore cylinders do not require machine work.Replacement Part for OEM...$421.95 -
Out of stock
Cylinder Works - 41004-G01 - Big Bore Gasket Kit - Suzuki
Cylinder Works
$68.95Cylinder Works - 09342151 - Big Bore Gasket Kit - SuzukiFeaturesCylinder kit includes matched Vertex pistons to ensure longevity, performance and reduced engine noiseNickel Silicon Carbide plated for...$68.95 -
Out of stock
Cylinder Works - 51001-K01 - Cylinder Kit - Big Bore - 90.00 mm - KTM
Cylinder Works
$982.95Cylinder Works - 09310410 - Cylinder Kit - Big Bore - 90.00 mm - KTMFeaturesCylinders have a nickel silicon carbide cylinder sleeveLook virtually identical to OEM cylindersKit includes cylinder,...$982.95 -
Out of stock
Cylinder Works - 10002-K01HC - Cylinder Kit - High Compression - 96.00 mm - Honda
Cylinder Works
$747.25Cylinder Works - 09310291 - Cylinder Kit - High Compression - 96.00 mm - HondaFeaturesCylinder kit comes with matched Vertex pistons to ensure longevity, performance and reduced engine noiseKit...$747.25
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.