Motorcycle Fork Top Cap Air Valves / Ports

If your motorbike has modern "Separate Function Forks", you probably have a comp adjustment clicker on one top cap & reb on the other, but for many adjustable designs both caps have compression damping adjusters - learn more about open or closed chamber front forks. If you've never adjusted your dampers, read our clickers article - they're like opening or closing a tap for more or less suspension oil to flow.

Adjuster assemblies are compact but complex - sealed on the upper fork tube is a top cap with an o-ring, the clicker assembly inside. Also screwed into that cover will be one of these two types of port; if your forks run oil there will be an emulsion bleed bolt so you can drain out any frothy mess, or if your bike has air forks there will be a Schrader (tyre) valve so you can hand pump them to the right pressure. These ports need their own sealing o-ring, and a valve cap to keep gunk out of the gas stem core too.

A threaded hollow centre shaft is screwed underneath each upper cap, with connecting push rods sliding inside, pressing harder or softer on the valves depending on your clicker adjustments, compressing or loosening the stack. At the bottom end are machined damping pistons, sealed with an o-ring or soft band. With shims & valving washers assembled either side, they're locked onto a base valve post using a locknut.

A free piston slides up & down the centre shaft, with inner & outer seals plus bushes to prevent oil getting past. An Inner Chamber Spring presses between the cap & the sliding piston - helping set the initial fork plushness - so changing how strong the ICS is will make the forks feel softer or firmer at the beginning of the stroke.

If you can't find what you are after, we have a collection of small clicker parts in our Fork Adjuster Parts category - plus we have some great aftermarket parts for comp assemblies like clicker knobs and super strong billet alloy free pistons.