Z1OwnersClub GB

Bought my 900 via a third party as a part started kz900c to A4. I ordered a hf401 filter (paper type) from dave, however when removing the old filter it is the taller metal canister type. Which leads me to wonder if the engine is not prehaps the original, the barrels are marked 903, the engine number begins Z1E12513 (apologies i am at work and looking at a pic i have which does not depict the full number)

My May '76 Z900-A4 engine number starts Z1E115*****, so your's is definitely a later motor. My barrels have "903cc" cast into the lower R/H corner, (forward facing side) & they are also the original barrels.

I'm sure I've read on here in the past that earlier barrels might just have "903" cast on them, or something like that unless I am dreaming this up. I'm sure someone will be along soon who really knows what they are talking about !!

all the z1/z900/ z1000a models use the metal perforated oil filter

Here's engine numbers from some 900s I've had:
z900a4 - Z1E093793
z900a5 - Z1E123346
z900a5 - Z1E103458
So, I'd say you have a very late z900a5 engine.

thanks Guys , I must have been sent the wrong filter phew