Another jetting question

KZ1000P (J model) brand new rebuild, 1075 kit, valve job, new cam chain, stock cams, stock ignition, stock exhaust, airbox with KN filter, BS34 Mikuni's.

Will the jetting need to be changed now that the bore is bigger?

I don't think it is required, but Wired George would be the expert on this kind of thing. I think you could get better performance going to different carburetors with a higher CFM flow, but I am not sure changing the jets in these will do what you want.

The 34s are enough carburetor due to the fact that everything els is the same. Your engine however will develop a bit more vacuum due to the larger displacement. This means that in fact you may go one size smaller in jets. For the time being though I don't think you will have to do anything.

This question can't be answered because you didn't say if the bike had been rejetted prior to what appears to be some engine work. If it has the stock jetting and these mods were made, it will need to be rejetted a bit. The BS34s are more than adequate for the minor work that was done.

carbs are stock

127.5 mains
37.5 pilots
stock needles

For whatever it's worth. Aren't these carbs. off a smog motor? They were lean from the factory due to EPA. You have a 1075 kit at risk here. What is cheaper, Richer jets to be safe side at 1st. or Buying new 1075 pistons. I would hope that it has better lungs now vs.stock. I can only afford one set of pistons myself. Treat them nice!

You certainly won't hole a piston using the stock jetting. The K&N drop in filter doesn't make a great difference. Try the stock jetting and see how it runs. If it starts a bit hard, then perhaps a larger pilot jet (#40 BS30/96 type) might be needed. Try and pull redline. If it pulls redline cleanly, your jetting should be OK as is; otherwise you might need a slightly larger main jet (perhaps a #132.5)