Ok everyone,
I found 2 spare B stamped original pistons
amongst a load of spares in my garage.
Seeing as I still have to install both cylinders I may aswell
fit these parts now.
The bores on the cylinders seem to be in very good condition.
My question is what does one have to do to the bores
to fit the new pistons?
Light sanding with fine sandpaper to remove the bore glaze?
Or just bung them in
without any prep. of the bores?
Cheers.

It's very rare to need to do anything to the bores, unless you were a victim to a partial seizure or extreme wear. Generally, you can just fit the new pistons if you can still see some cross-hatched honing marks. The Nikasil is "rock hard", so just leave the surface as it is, if it's free of any molten piston! There shouldn't be any glaze, like you can sometimes see with iron bores.

There is no harm in giving them a little tickle with some wet'n'dry paper around the exhaust port bridge, just to make sure there's a little relief (this area expands the most during running, so ends up with the tightest clearance), but it's rarely an issue, really.
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Andy.
NSR-WORLD.COM

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Thanks Andy.
I just reused the pistons that were there, perfect condition
ascarecthe bores too.