These refer to Pike air u-turns btw:

1) What does it mean if when returning to full extension there is a quiet bang/knock?

2) When there is say 10-20psi more in the lower (-ve) chamber should this reduce availible travel? by say 20mm?

3) when there is more psi in the upper (+ve) chamber should this reduce availible travel?

4)Should oil leak out of the valves during pumping up/down of the chambers? is it just a case of turning them skywards when adjusting?

5) With forks locked out and brake on, when rocking forwards/backwards there is movement felt. checked and tightened headset/brake, bushings gone?

6) the number eg 05 stamped beneath the crown refers to year of birth?

Thank you for your time

not a definitive list of answers but:

1 rebound may be set too fast
2 neg presure should be equal to pos with up to 10psi more, yes it will reduce the static sag slightly but just take that into account when setting the sag with you on it.
3. more psi in +ve is the same as a heavier duty spring, you will need more force to move it and get it bottom out/use full travel
4. Yep that's normal as long as it's only a smidge.
5. possibly

TF tuned have a good troubleshooting FAQ for forks that may be worth you having a look at.

thank you for the reply!

have adjust rebound and matched air pressures to avoid confusion.
There is still a definate knock when you compress the forks, and you can see the seal getting slightly squashed when you rock on them like the fork is bending at the middle…suggesting worn bushings?

ah yeah just checked the faq on there, apparantly the knocking is normal….dubious!

Mine have a sort of a "knock" in the first few mm of travel.. my Recons did the same as well. Feels a bit like a loose headset. When riding you don't notice it as they've already got past that initial knock (it's included in the sag). Didn't know if it was normal or not..

2) yes
3) no, it should it make it harder to 'activate' the travel

"3. more psi in +ve is the same as a heavier duty spring, you will need more force to move it and get it bottom out/use full travel"

I don't think it does. I assume the OP meant more psi in the +ve that psi in the -ve, in which case it doesn't act the same as a heavier duty spring. If both the +ve and -ve were increased then yes it would
With the +ve more than the -ve, the ive has less pressure to push against the +ve pressure, taking a bigger bump to get the fork moving (to overcome the stiction) over a bump

Sorry to hijack this thread but does anyone have any firm Pike springs? Thanks.