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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- Qty in Cart
- Quantity
- Price
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Prox - 29.748240 - Valve Shims - 7.48 mm x 2.40 mm - 5 pack
Prox
$10.95Prox - 09260894 - Valve Shims - 7.48 mm x 2.40 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 29.VSA748 - Valve Shim Kit - 7.48 mm x 1.20 mm - 3.50 mm - Multiple Models
Prox
$116.95Prox - 09261018 - Valve Shim Kit - 7.48 mm x 1.20 mm - 3.50 mmFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$116.95 -
Prox - 29.100285 - Valve Shim - 10.00 mm x 2.85 mm - 5 pack
Prox
$9.95Prox - 09261010 - Valve Shim - 10.00 mm x 2.85 mm - 5 packFeaturesPrecision machined to match exact sizeSpecsOut$9.95 -
Prox - 29.100275 - Valve Shim - 10.00 mm x 2.75 mm - 5 pack
Prox
$9.95Prox - 09261008 - Valve Shim - 10.00 mm x 2.75 mm - 5 packFeaturesPrecision machined to match exact sizeSpecsTyp$9.95 -
Prox - 29.100305 - Valve Shim - 10.00 mm x 3.05 mm - 5 pack
Prox
$9.95Prox - 09261014 - Valve Shim - 10.00 mm x 3.05 mm - 5 packFeaturesPrecision machined to match exact sizeSpecsUni$9.95 -
Prox - 29.748215 - Valve Shims - 7.48 mm x 2.15 mm - 5 pack
Prox
$10.95Prox - 09260889 - Valve Shims - 7.48 mm x 2.15 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 29.748230 - Valve Shims - 7.48 mm x 2.30 mm - 5 pack
Prox
$9.95Prox - 09260892 - Valve Shims - 7.48 mm x 2.30 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$9.95 -
Prox - 29.748185 - Valve Shims - 7.48 mm x 1.85 mm - 5 pack
Prox
$10.95Prox - 09260883 - Valve Shims - 7.48 mm x 1.85 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 29.748235 - Valve Shims - 7.48 mm x 2.35 mm - 5 pack
Prox
$10.95Prox - 09260893 - Valve Shims - 7.48 mm x 2.35 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 29.748320 - Valve Shims - 7.48 mm x 3.20 mm - 5 pack
Prox
$9.95Prox - 09260910 - Valve Shims - 7.48 mm x 3.20 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$9.95 -
Prox - 29.748140 - Valve Shims - 7.48 mm x 1.40 mm - 5 pack
Prox
$10.95Prox - 09260874 - Valve Shims - 7.48 mm x 1.40 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 29.748280 - Valve Shims - 7.48 mm x 2.80 mm - 5 pack
Prox
$10.95Prox - 09260902 - Valve Shims - 7.48 mm x 2.80 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 29.748275 - Valve Shims - 7.48 mm x 2.75 mm - 5 pack
Prox
$10.95Prox - 09260901 - Valve Shims - 7.48 mm x 2.75 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 29.748265 - Valve Shims - 7.48 mm x 2.65 mm - 5 pack
Prox
$9.95Prox - 09260899 - Valve Shims - 7.48 mm x 2.65 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$9.95 -
Prox - 29.748285 - Valve Shims - 7.48 mm x 2.85 mm - 5 pack
Prox
$10.95Prox - 09260903 - Valve Shims - 7.48 mm x 2.85 mm - 5 packFeaturesPrecision machined to match exact sizeInexpensive and easy replacement for expensive OEM shimsSpecs$10.95 -
Prox - 01.1320.A1 - Piston Kit - 66.35 mm - Honda | Husqvarna | Suzuki
Prox
$143.95Prox - PX4430B - Piston Kit - 66.35 mm - Honda | Husqvarna | SuzukiFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely...$143.95 -
Prox - 01.4285.B - Piston Kit - 65.95 mm - Kawasaki KDX200
Prox
$132.95Prox - PX4310B - Piston Kit - 65.95 mm - Kawasaki KDX200FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$132.95 -
Prox - 01.1218.A4 - Piston Kit - 53.97 mm - Honda CR125R
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$132.95Prox - PX4260D - Piston Kit - 53.97 mm - Honda CR125RFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$132.95 -
Prox - 01.1408.100 - Piston Kit - 90.00 mm - Honda CR500R
Prox
$199.95Prox - PX4044 - Piston Kit - 90.00 mm - Honda CR500RFeaturesPrecision machined on state of the art CNC equipmentMade with low expansion, low friction alloyKit includes piston, rings, circlips and...$199.95 -
Prox - 01.1218.A1 - Piston Kit - 53.94 mm - Honda CR125R
Prox
$132.95Prox - PX4260A - Piston Kit - 53.94 mm - Honda CR125RFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$132.95 -
Prox - 01.2217.D - Piston Kit - 53.98 mm - Yamaha YZ125
Prox
$121.95Prox - PX7215D - Piston Kit - 53.98 mm - Yamaha YZ125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.2217.A - Piston Kit - 53.95 mm - Yamaha YZ125
Prox
$121.95Prox - PX7215A - Piston Kit - 53.95 mm - Yamaha YZ125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.1408.125 - Piston Kit - 90.25 mm - Honda CR500R
Prox
$185.95Prox - PX4045 - Piston Kit - 90.25 mm - Honda CR500RFeaturesPrecision machined on state of the art CNC equipmentMade with low expansion, low friction alloyKit includes piston, rings, circlips and...$185.95 -
Prox - 01.2114.A - Piston Kit - 47.44 mm - Yamaha YZ85
Prox
$99.95Prox - PX2112A - Piston Kit - 47.44 mm - Yamaha YZ85FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$99.95 -
Prox - 01.2224.A - Piston Kit - 53.94 mm - Yamaha YZ125
Prox
$121.95Prox - PX2222A - Piston Kit - 53.94 mm - Yamaha YZ125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.1408.050 - Piston Kit - 89.50 mm - Honda CR500R
Prox
$185.95Prox - PX4042 - Piston Kit - 89.50 mm - Honda CR500RFeaturesPrecision machined on state of the art CNC equipmentMade with low expansion, low friction alloyKit includes piston, rings, circlips and...$185.95 -
Prox - 01.2215.C - Piston Kit - 53.96 mm - Yamaha YZ125
Prox
$121.95Prox - PX7214C - Piston Kit - 53.96 mm - Yamaha YZ125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.2321.A - Piston Kit - 66.35 mm - Suzuki RM250 | Yamaha YZ250/YZ250X
Prox
$132.95Prox - PX7130A - Piston Kit - 66.35 mm - Suzuki RM250 | Yamaha YZ250/YZ250XFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to...$132.95 -
Prox - 01.4218.C - Piston Kit - 53.97 mm - Kawasaki KX125
Prox
$121.95Prox - PX4299C - Piston Kit - 53.97 mm - Kawasaki KX125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.2321.C - Piston Kit - 66.37 mm - Suzuki RM250 | Yamaha YZ250/YZ250X
Prox
$132.95Prox - PX7130C - Piston Kit - 66.37 mm - Suzuki RM250 | Yamaha YZ250/YZ250XFeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to...$132.95 -
Prox - 01.3320.A - Piston Kit - 66.34 mm - Suzuki RM250
Prox
$143.95Prox - PX5200A - Piston Kit - 66.34 mm - Suzuki RM250FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$143.95 -
Prox - 01.4218.A - Piston Kit - 53.95 mm - Kawasaki KX125
Prox
$121.95Prox - PX4299A - Piston Kit - 53.95 mm - Kawasaki KX125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.3214.B - Piston Kit - 53.95 mm - Suzuki RM125
Prox
$121.95Prox - PX5050B - Piston Kit - 53.95 mm - Suzuki RM125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.4121.A - Piston Kit - 48.45 mm - Kawasaki KX85
Prox
$99.95Prox - PX4281A - Piston Kit - 48.45 mm - Kawasaki KX85FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$99.95 -
Prox - 01.2224.B - Piston Kit - 53.95 mm - Yamaha YZ125
Prox
$121.95Prox - PX2222B - Piston Kit - 53.95 mm - Yamaha YZ125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.3320.B - Piston Kit - 66.35 mm - Suzuki RM250
Prox
$143.95Prox - PX5200B - Piston Kit - 66.35 mm - Suzuki RM250FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$143.95 -
Prox - 01.4322.C - Piston Kit - 66.36 mm - Kawasaki KX250
Prox
$143.95Prox - PX4308C - Piston Kit - 66.36 mm - Kawasaki KX250FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$143.95 -
Prox - 01.3214.C - Piston Kit - 53.96 mm - Suzuki RM125
Prox
$121.95Prox - PX5050C - Piston Kit - 53.96 mm - Suzuki RM125FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$121.95 -
Prox - 01.4285.C - Piston Kit - 65.96 mm - Kawasaki KDX200
Prox
$132.95Prox - PX4310C - Piston Kit - 65.96 mm - Kawasaki KDX200FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$132.95 -
Prox - 01.4285.A - Piston Kit - 65.94 mm - Kawasaki KDX200
Prox
$132.95Prox - PX4310A - Piston Kit - 65.94 mm - Kawasaki KDX200FeaturesCast from a high-silicon-content aluminum alloy that meets or exceeds OEM specifications, then CNC-machined to extremely close...$132.95
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.