Just wondering why my forks are not extending fully when I comress them ?, I rebuilt them couple of years back and they seem OK individually but hard to test on the bike, they return if I live the bars but should the fork springs do this automatically ?....it's not a big problem but they just don't see right .

You might want to check that you have your front wheel axle assembly correctly put together.  On my DT1 I had a washer/spacer in the wrong position so when I tightened the axle it put the forks in a bind and they would not return, just like you described.  After studying the wheel and parts pics avialable on line I moved/added the spacers/ washers around and sloved the issue.   Went out and took another look at my front wheel and I did indeed move a washer from one side to the other.  So, my wheel is not assembled according to the parts picture but the forks are not binding.  I have been riding it that way for a couple years.  Guess the next step is to take some time and figure out the issue.

 

Loosen everything, make sure its not binding. Fork braces can cause binding of not installed properly. 

Thanks guys, no fork brace fitted I will have a look at the spindle/spacers tomorrow if I lift the bars they do pop out more ?, do the springs return the forks upwards ?, from what I can remember they don't seem over stiff....?

Check your fork stauchions are straight .
If there is a bend in there , depending on where the staunchion is sitting ,
the staunchion and slider could bind . Rotate each staunchion through 360 degrees
at 90 degree intervals . If there is a bend on one or both tubes ,
the distance between the sliders at the axle will change .

Forks are dead straight they were re-chromed as part of the rebuild

Swoop56 wrote: Check your fork stauchions are straight .
If there is a bend in there , depending on where the staunchion is sitting ,
the staunchion and slider could bind . Rotate each staunchion through 360 degrees
at 90 degree intervals . If there is a bend on one or both tubes ,
the distance between the sliders at the axle will change .
 

Well it's not an alignment problem, just slackened the spindle nut and the forks are independant of each other, anyone have any idea how strong the springs should be ?, if I place the bike on its side stand the forks extend further up as the weight of the bike is reduced on the springs ?.It's almost like the springs are too soft ?

Are you expecting the forks to be "topped out" unless you hit a bump?  That's not really good suspension.  Some sag is beneficial.  

You haven't said anything about how much travel you're talking about here?  A few mm?  Half the fork travel?
 

It's a bit hard to quantify, I hold the brake and push down on the forks they go down as you would expect but they seem lazy to return when I stop pressing, they return a couple of inches then stop but if I lift the barsd lightly or use the side stand they will pop up another couple....?

Possibly your  springs are just suffering from age.  One suggestion is to install some spacers above your springs, which may take up the slack.  Your springs are the same as my DT1-250, 214-23141-00-00 which have a standard length of 438mm.  You can pull yours to measure and see if they are not to length.  Then fabricate a spacer to compensate for the shortfall.  Attached is a service bulletin for DT1's, & RT1's that use the same spring which might be of some help, if you do not already have it.