fletcher said:
how will i go if i jack the front end up so the wheel dosnt touch and undo top screws and pull out springs and try a bit more oil in both then reinsert the springs and caps and try or should i compress forks up again and check level.
That's what I would do. I think I would meaure first and see if you are still at 4" (or approx. 100 mm) oil height at full compression with springs removed and forks compresssed. If not, raise oil to 4". If you are already at 4", add enough oil to raise to 3.5" from the top.
It might be useful to know how much oil it takes to raise the level 1/2" (12.7mm), so pour from a pre-measured amount. That way if you need to add or remove oil again to adjust the fork, you don't have to spend as much time measuring.
If you get too high on oil level, the forks will feel fine during the first few inches of travel, but may not be able to compress all the way when the springs are in. You probably won't run into a situation where you are losing fork travel until you are less than 3" from the top on oil level. I don't think I would go less than 2.5".
Basically, the air in the fork gets compressed as your suspension bottoms, and helps stiffen up that last part of your fork travel. By having more oil, you have less room for the air to compress into at full compression. This makes the fork stiffer as it nears full compression. If you have the oil too high, there is no room for the air to compress into and the fork loses travel.
You basically want the oil level low enough so that you still use full travel on big hits, but high enough so that your fork is stiff enough on the big hits. This takes some fine tuning, but once you get it set, the fork should work better for you.
On many of the older bikes, the factories did not put in enough oil (my old '84 KDX200 was more than 6" from the top). So if you do find a shop manual that tells you how many cc of oil you need, you would still need to fine tune it to work best for you.