Top-end rebuild checklist
Everything you need for a top-end rebuild in one place, so you can order the right parts first time and avoid waiting for a missing gasket.
The rebuild in six steps
Strip and inspect
Remove the head and barrel. Look for scoring, seizure marks, broken rings and wear on the small end.
Measure
Measure the bore and the old piston. Our piston size guide shows how.
Decide the size
STD if within limits, the next oversize if a rebore is needed, or a liner if the bore is beyond its last oversize.
Order the parts
Use the checklist below. A bundle gives you pistons, bearings and gaskets in one order.
Machine work
Send the new pistons with the barrel so the engineer can bore and hone to suit them.
Build and run in
Assemble with new circlips and gaskets, set the torque figures from your manual, and run the engine in gently.
Parts checklist
Tick these off before you start. Not every engine needs every part.
Piston kits
Piston, rings, gudgeon pin and circlips
Shop now →✓Piston ring sets
If the pistons are re-used
Shop now →✓Gasket sets
Head, base and other top-end gaskets
Shop now →✓Small end bearings
Two-strokes - fit new with new pistons
Shop now →✓Circlips
Always new - never re-use old ones
Shop now →✓Piston pins
Replace if worn or marked
Shop now →✓Inlet valves
Four-strokes - while the head is off
Shop now →✓Exhaust valves
Four-strokes - while the head is off
Shop now →✓Cylinder liners
When the bore is beyond the last oversize
Shop now →✓Rebuild bundles
Pistons, bearings and gaskets together
Shop now →Two-stroke or four-stroke?
Two-strokes usually need pistons, rings, small end bearings, circlips and a top gasket set. Four-strokes usually need pistons, rings, circlips and gaskets, and often valves and valve stem seals while the head is off.
Order everything together
Ordering all the parts at once means one delivery and no half-built engine waiting for a missing gasket. Free UK delivery on orders over £100.
Rebuild questions
Do I need a rebore every time?
No. If the bore is within the wear limit and is not scored, a hone and new rings (or a standard piston kit) may be enough. Measure first - see our piston size guide.
Which bundle is right for my bike?
Bundles are listed by model. Search for your bike in the bar at the top of the page, or browse all bundles.
Can you help me choose the parts?
Yes - contact us with your bike model, year and bore measurement and we will put the list together.
Ready to order?
Find every part for your rebuild by searching your bike model, or let us help you build the list.