How do I add fork oil into my 04 450f and how much ?

The amount of oil that goes in the forks of a 1982 Suzuki GS 750T will depend on the type of forks that are installed on the motorcycle. It is important to use the correct amount of oil to ensure that the forks are functioning properly.
If your Suzuki GS 750T has standard telescopic forks, you will need to add 10.8 ounces (320 mL) of fork oil to each fork. If your motorcycle has air-assisted forks, you will need to consult the owner's manual to determine the correct amount of oil to use.
To add oil to the forks, you will need to remove the fork caps and use a fork oil level gauge or a piece of wire to measure the amount of oil in the forks. If the oil level is too low, add oil until the forks are filled to the correct level. If the oil level is too high, remove excess oil until the forks are at the correct level.
I hope this information helps! Let me know if you have any other questions.

Question edited for clarity.

Fork oil change.

http://v4musclebike.com/forums/showthread.php?t=1604

Full rebuild

https://www.google.com/search?q=1998+honda+magna+750%2C+add+oil+front+forks

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there is a car at the top of the fork which it has a spring and the oil should be drained out from the bottom of the fork little screw look in owners book make sure you only add the right cc of oil and should always do both must use yamaha fork oil or comp oil only

Is you have taken the forks apart and changed the fork bushes, ie forks are totally dry, you will need about 520ml in each fork leg. When refilling and will the springs removed, add about 550ml per leg, the stroke the forks numerous times to expel any excess air. Then with forks compressed the oil level should be adjusted to 119mm from the top of the fork to the oil, ie the air gap to the oil. The add springs and spacers and reassemble.
Red zed.proboards.com

Do not add oil too your forks. Too much oil will jam the forks up, damaging the fork tube chrome and the fork bushings. If you suspect incorrect oil levels in the tubes, drain the tubes and refill them with the correct amount of oil. If there is too much pressure in the system, then loosen an air tube and bleed off the excess pressure. You may have a defective air pressure valve or pump. Parts that may or may not be available from the local dealer any more. More information can be found at ngwclub.com or Randaaks.com. Do not over fill your forks with oil. Let the air pressure out of your forks.Use the compressor on the GL1200 to reduce or add air pressure to the forks. The controls for the compressor are located on the dash. Turn the key the "On" position to use the compressor

Yes. Unscrew the fork caps one at a time and push the front end down just enough to get a turkey baster or syringe to the inside. Unless you've lost alot of fluid, just add in 10cc increments. If you get too much in them, the forks will get really stiff.

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First of all don't add oil, change it. to drain your oil you need to remove the air tube, remove the front wheel, loosen the allen screw on the bottom of the fork, unscrew the fork top, then remove the fork tube, and turn it over to drain(be careful internal parts of fork will come out)remove parts clean and inspect. Reassemble in reverse order,snug up the screw on bottom, fill top with correct oil qty,cap top, tighten bottom and finish reassembly.

just pour oil in the top of the fork compressing the forks at the same time notice it will sqweel a lot as this is happening keep pumping the forks till the sqweeling stops fill each leg with 459mls buddy

change the oil seals and oil in the fork,and avoid wheelies on the bike and off road biking 

set your compression out 10 or 11 your rebound 9 or 10 and your fork oil height to roughtly 380cc.since its in 03 u should drain the fork oil out, u have to unscrew the top cap of the fork while its in the triple clamps( because its easier this way), loosen then take the fork out of the clamps, unscrew the top caps and pull the fork tube down and turn the fork upside down to drain the oil out then hang the forks up upside down for about 15 minutes then add the new oil right in the fork tube were you'll see a spring, just add the oil in there and you'll be fine and u should replace it with a good medium weight oil