Totally agree with Al1040. Change the fluids and verify the spring condition. Something like this makes it easy to set the fluid level with precision.
https://www.motionpro.com/product/08-0121

 

Ok a couple things here. First off, you have an F, not an F sport. In europe that matters. America only got the sport model, even when it switched to the single seat found on the non sport models in europe. Second, non-sports come this way from what I've read. Any sport model has adjustable and everything swaps over no problemo. Lastly, forget these two guys and YES MAKE THE SWITCH. Its a night and day difference. I don't know about the non adjustable model forks, but the US models are sprung for a 90lbs rider. Meaning, they are absurdly bad from the factory for average weight people. Just adding heavier springs makes the rebound damping useless and the compression damping almost too much to work as well although it is doable especially if you drop to 5wt oil vs the factory 10w. If the non adjustables are the same way, and you add a correct spring, you won't be able to adjust the shims in the dampers to make the fork work correctly.

 

The OP never said he had a sport, they were only available in the UK for two years until the RR came along. The F had the fully adjustable forks 2001-2004 and then changed to the non-adjustable forks for 2005-2006.
I (a 180 lb rider) rode a 2005 F for some 25k miles up and down the Alps etc and never felt the need for different forks from my own personal and relevant experience, but each to their own, I am sure the OP will make his own mind up with help form this forum, we are offering help and guidance.
Honda do not make a bad motorcycle for 99% of the population. There is always the 1% that need something different.

 

Thanks all, I managed to have a go on my dads friends F4i 2003 with adjustable forks and he let me have a play around with the set up, in my opinion there is a minor difference but nothing substantial. Anybody good with the paint codes on these? I have the R157 code under the seat for the red but the fairing is black paint with red decals? I need the paint code for the black to be able to sand and re spray fairing.

 

I think it is NH-1, possibly NH-1Z

 

Agree, Honda refers to it as NH1. However something that I noticed recently on my F3. The tail sections on my bike are not painted from the factory. The black is actually the color of the ABS plastic they're made of.