Honda-SOHC

Thanks K2-K6, answers my original question as to whats the front of the piston.
I don't think the top pocket has been re-cut, I think a valve has been hitting it.
Yup, the small triangles at 2 o'clock are just small dents with carbon, not anywhere the ring land.
Pistons could have been turned as the valves I took out did not match and I recon it either dropped a valve at some time or a valve head decided to part company with the stem and possibly someone cleaned the damage on the piston top.
I am fitting brand new valves from Cyclex in the USA and had to replace one of the liners which had a big gouge out of the side wall, funnily enough the shape of a valve edge.
I will indeed take onboard your suggestion with the plasticene. Going to re-build everything without torquing the head down and look at the valve clearances.
Again, many thanks for your advice.

Just checked the original needles that were in the carbs when I got them and they are the same as the upgrade needles. Must have already had the fix.

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It was yes to the F2 speedo face having MPH and KPH markings

Like this:

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I know what you mean Ash, but they do appear to be good quality. As with the rubber bits they may dissolve when you oil the chain though. Actually their piston kits are very high quality.

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Yes

Ash, I'm not sure if you are answering the answer before or the thread question.
I'm coming across images of F2s with both options, what to think? Is it really a worry that the face plates I bought for my F2 some years ago have MPH only, which is what I have now, but I've rooted out a number of home made and ill fitting parts on this bike!