Z1OwnersClub GB

Has anyone got a No3 cam bearing cap they would be willing to sell as I just broke mine while tightening down the cams, not paying attention doh!.
Hope someone can help me out thanks

Not necessarily as easy as that mate, cam caps are machined to match the head that they came from, if you fit a cap that is off another head you could be in proper trouble. Is the head still on the bike?

Where is it broken ???
If it's the joining bridge and not one of the actual saddles you don't need another cap and can use what you have.
Caps are line bored with each individual head so it's not a simple job of just bolting on another one.
You need a bucket full of spare caps to find one that doesn't bind the cams or some careful "adjustment" to one that does.

It snapped in half with most of the bridge on the left side
Head is off the bike

You can either just fit the cap as is or remove the bridge to leave two seperate saddles.
Leaving the cap as is allows you to easily maintain the correct orientation and if you remove it you will have to mark each saddle to identify their correct locations and direction.
A simple dot punch mark on one and two on the other with corresponding marks on the head is simplest method.
You could also have the bridge tigged back together whilst bolted to the head with cam and shells in situ to maintain alignment but there is a risk of distortion and then cam binding.

As an addition to the above.
Numbers one and three cam caps control cam end float.
If removing the bridge then be careful to avoid the machined thrust faces on the inside of the saddles if tidying them up with a file.
If either using the broken cap as is or removing the bridge the end float will not be compromised as the individual halves are dowelled and will self align parallel when bolted down.