Thanks for the response.

Jets are all clean.

I've had the carbs off the bike. I separated them, took the float bowls off and gave them a petrol bath. Mid range and top end were heaps better when i put them back on and as I said, the plugs look a lot better now.

How do you check for wear on the air screws? Which parts wear?

I had them out today, there's a couple of marks on the sides but that's it.

The ends taper, but the tip is flat. Is this normal, or should they be more needle like.

As far as air hoses go, I have recently replaced them as per the illustrations. Unfortunately the cross piece was broken so I have emulated it with two T pieces to make an offset cross. All hoses that would normally go the the air box now just vent to atmosphere.

Oil pump *looks* ok. I didn't check it specifically as it seems to be coming on with the throttle just fine.

Maybe I should disconnect it and try some premix.

All other suggestions are welcome - She's currently sitting tank off in the garage so I can get straight back into her.