No problem Evil.

These are some rough measurements of zxr400l valves.
in dia 17mm length 84mm.
ex dia 22mm length 85.5mm.
I don't know the stem dia.

Thanks for dimensions, will check this weekend as I am away until then.

Funny how things work out.
A month ago I had a completed bike ready to tax.
It would not start due to what I believe was lack of compression due to some tight valve clearances the compression gauge that told me "all was ok" was taken by the recycling van a month ago.
During the fault finding process i have identified High Tension side electrical problems
In the last month I have stripped the top end
Had the valves ground and the seats re-cut
had the head skimmed
Rebuilt the head and achieved all the correct valve clearances.
Now ready to rebuild this weekend
I just bought this bike cheap to do a cosmetic job and ride to the North West 200
I have everything I need to complete the bike but will I finish it in time to get there?
If its not finished I have a Triumph Sprint which I can use
How things have changed from my youth that a Triumph may be more reliable than a Yamaha
Funny old World!

Having 16 valves is a pain in the arse on the work bench but I suspect different on the road.

Will keep all posted regarding my own race to get to the North West

Arf !!!
On the flip side though, you'll have a fully sorted FZR which will be rewarding to ride and you'll probably find it quite reliable. They are getting to be older bikes now and will need a bit of engine work, but that should see them good for a while afterwards maybe another decade. They do tend to suffer from first time owners though.

$ valves a cylinder, tis witchcraft

Just a few further irritating questions as I intend putting it back together this weekend between getting a few miles in on the 750 turbo.
Sealant on the base gasket?
Sealant on the head gasket?
Anything else to what out for?
I have made 4 ring compressors from plastic waste pipe to be held in place by zip ties to compress the piston rings when putting the barrels back on.
Thanks

No sealant on either gasket.

You only need 2 compressors, 2 cylinders are up and 2 are down. Put a piece of equal sized wood / alloy under the front and back of the 2 pistons your feeding in - this locks them and keeps them perpendicular to the block

Reason for 4 is that they are cheap an easy to make and when the first two pistons are in you don't have to F about trying to fit the next two as they are already on. Used the technique for years. I will try to video it and stick it on YouTube but I am shit at that sort of thing.

Cool - you have a lot more experience than me

I doubt that Evil, I generally do most things twice to get them right.