I have had both fork seals replaced and the steering head bearing but I am still getting a knock when the forks are under compression - not all the time though , it happens just after they start going down but I dont think they are bottoming out but I cant pinpoint it , anybody else ever had this

does it make the sound when you initailly use the brakes when moving ?
or even when the bike is static with no fwd force?
to check if it the head bearings you need to support the bike so the front wheel is off the ground and free, then pull/push the bottom of the fork legs , (you can do this with the wheel on the ground but not as easily)
any movement will mean the head bearings have not been seated correctly before the stem collar was torqued up.

It happens initially when braking , I will try the tests you mentioned when I get the bike out next to get a better idea , if it is this then it's going straight back for repair !!

You might want to have a look at the fork bushes too while you're at it.

Ok, im more than likely way off but I think worth checking anyway as noises can appear to be from one part but actually come from other places. I once blamed my new chain/front sprocket only to find a semi seized rear caliper was causing the problem but it sounded as though it came from the front sprocket, a bit of a clean and copper slip to the caliper sorted it.

So, have you checked your calipers are floating correctly, also the brake caliper pins maybe worn and causing the pads to jump before they settle in place.

hope it helps

dave

In a similar line to durka durkas post, have you got tank rubbers on?
First time I rode a bike without them all sorts of weird and wonderful noises came from what seemed like all over the place.
Obv just the tank vibrating and banging about, but some interesting noises none the less.

Check your mudguard clamps..they rattle and knock when they get loose...

Check for play between your front brake disc rotors and their carriers, this can seem like a fork 'knocking'.

I have new tank rubbers on there but I have found that one of the calipers seems really loose , i have taken out the bolts cleaned everything and put them back but it still seems to be loose for some reason ( front left ) the right one is still moving / floating freely but has much less movement

I would now check for a sticking piston and really check those caliper pins (the ones that hold the pads) for wear, perhaps swap em round and copper slip them if you have no spares, see if there is any change.