Front fork seals on 1999 cbr 900 leaking

G'day. A couple of suggestions-
Damage to the fork slider-chips or dings.
Too much oil in the fork on re-assembly can cause the seal to go.
Worn or loose fork bushes will flog the seal prematurely.
When you transport the bike-if you don't use a seal saver can pop the seals.

So let me help with these.

Be sure that the fork slider is not scored,dinged or damaged on th surface.

A good double check of the oil quantity is to ensure that when you have re-filled the tube with oil & primed it(worked the air out of it), the oil level should be 100 to 110 mm from the top of the leg to the oil with the fork fully compressed. If the level is less than this-drop it to 100mm.

To check the fork bushes-try pull on the front forks front to back(wobble) & feel for looseness in the bushes.

And finally-When you transport the bike-put a chock(I use an empty 5ltr oil container-but you can buy propper chocks from the bike shop) in-between the forks at top of the front wheel .
Now when you pull the front end down it will stop on the chock & stop the front forks being under excessive compression for extended periods-so it saves the fork springs from sacking out too.
I hope this proves helpfull.
Kind regards Andrew Porrelli

Your front fork seal are bad and need to be replaced.
When you loose fork oil, your loosing suspension dampening and only riding on the springs.(POGO)

Replace both front fork seals and dust caps, and put same amount of fork fluid in both forks.

I bought my seals and caps for $30 on ebay, and then took my forks off my bike and took them to a shop and they charged me $75 to do the job.

You can take them the whole bike and they will charge $100 - $150 including parts to do the job.

HI WEATHER YOU NEED TO SPLIT THE FORKS OR NOT, YOU SHOULD, SOME OF THE OLDER HONDAS REMOVING THE LOWER FORK BOLT, ACCESABLE WHEN THE SPIINDLE HAS BEEN REMOVED, THIS WILL DRAIN THE OIL OUT OF THE FORK LEG THERE WILL BE A WASHER OR SEALING RING ON THIS SO BE CAREFUL NOT TO LOOSE IT WHEN YOU REMOVE THE BOLT, USING A BOWL OR CONTAINER TO CATCH THE OIL, UNDO THE BOLT IN THE LOWER FORK LEG, AFTER ALL THE OIL HAS BEEN REMOVED, PULL DOWN ON THE FORK TUBE IF THIS PULLS OUT OF THE LEG THEN YOU CAN COMPLETE THE JOB QUITE EASY, REMOVE DUST SEAL, CIRCLIP AND OIL SEAL, THE LATER WILL BE QUITE TIGHT IN THE LEG, WHEN YOU EASEMBLE THE FORK YOU WILL HAVE TO UNDO THE TOP FORK NUT TO REPLENISH TTHE OIL

It's hard to get specs in mls or cc these days so I'll let you in on a BIG secret(don't tell everyone,hush hush,& we stay wiser than others,promse not to tell, cross your heart).

Ok here we go- NO this ISN'T a joke so listen carefully.

Set the oil levels in the front forks

with the cartridges blead(simply draw up & down on the damper rod & you can feel the air bleeding out),

& before you re-fit the springs,

With the forks fully compressed
,
The fork oil level should be 100-110mm from the top.
This applies to basically all forks(except-a few like MX showa on certain RMs' & the new kawasaki 250 MXer.)
Hope this helps
Regards Andrew

If you have never taken your bike front-end off for any type of maintenance, you better get a friend who can show you step by step process, as it requires mtre just taking the fork off the bike once you get into the for to replace the seals and putting the fork oil into it.

no you can change the seal and the oil just make sure you measure the oil you remove and put the same amount back in

Popping out of gear denotes a slightly bent shift fork. If you have not bought the bike yet then don't buy it. Major cost to replace a shift fork.

If the seal has been cracked by the cold weather it should be replaced. For someone mechanicly inclined and with the proper tools this is not a hard job. For the novice it can be one of those times you could have sent it to the shop and spent less time and money, and gotten better results....
As to a seal conditioner, the seals today are generally made of synthetic material. No "conditioner" will work. If the seal is made of rubber you have a 90% chance that a product called 'MARVEL MYSTERY OIL' will solve the problem. This prouduct was created in 1917 and marketed in 1923. Google the product name for more hystory and uses today. Basicly, the oil causes rubber to swell. This tightens seals and thus fixes the problem. Most any good auto parts store has this stuff on the shelf. By the way, if the bike was purchased new, wouldn't this be a warranty repair?