I've been helping a mate get a few more ponies from his 1990 CE2 1.3 mk2. I fitted CBR carbs as a surprise for him, now he's found a fast Road cam and a 4 branch. I'm going to port, polish and 3 angle seat a head for it, as I have a spare. Are they all the same? The one I have hasn't any combustion chamber, the valves are at deck level. I really don't want to spend hours at this in case his one is different .