hi everyone........my cbr 400 nc23 j is off road till next month so decided to replace steering bearings as when i would go over a bump it would rattle......changed bearings but while i had forks in my hand i realised the problem is not bearings but forks as i can get about 5-10mm play up and down on them before they engage if you get my meaning...i have the bike 2 years and god nows when forks were last looked at (oil,springs ect). guy i bought it from put new seals on it before i bought it.....

priced up new springs oil and fork seals and comes to around 110 euro but i am wondering could the problm be that the forks need new oil and see if that solves problem?.. would be buying the parts and getting shop to fit them as i wouldnt be able to tackle that myself, plus i know it would be done right.

so really in my mind the play should not be there so therfore the forks are most likely the problem. am i talking sense or out of me hole.... anyone elses bike show this sympthom before and what was the outcome?

thanks guys

Something is not quite right matey...

It rattles over bumps -a knock?

But when the forks are off the ground you can move them, easily, up and down 5-10mm?

So when the fork has weight on it this movement does not matter?

Oil won't solve it - it is going to be something mechanical that needs sorting..

SO - check the bolts on the bottom of the fork are tight - not too tight. Check the front the rear play too - might be bushings worn.

CMSMJ1 wrote:Something is not quite right matey...

It rattles over bumps -a knock?

But when the forks are off the ground you can move them, easily, up and down 5-10mm?

So when the fork has weight on it this movement does not matter?

Oil won't solve it - it is going to be something mechanical that needs sorting..

SO - check the bolts on the bottom of the fork are tight - not too tight. Check the front the rear play too - might be bushings worn.

hi cmsmj1,

have front still lifted, and checked for play forward and back and side to side and nothing, its only started about 2 months ago....imagine going over bumpy road and the front hopping slighty....just enough for you to feel and hear....as soon as it happened checked every nut n bolt as i wouldnt ride it again until i was sure nothing loose.
wheel bearings are fine too by the way.
but is that small amount of movement normal if the fork??

cheers for replying

Is there any oil in the forks at all?

tanuki wrote:Is there any oil in the forks at all?

well there is good compression ...had forks off and pressed down on each of them individually and seemed ok.....if i opened screw slightly to check would it loose tension in the fork? sorry if thats a stupid question but dont want to mess about with them when not sure if what i would do would mess them up

if there is any fluid in it you should be able to hear it if you tip the fork, they will still get compression from the spring without fluid in.

petrolhead19 wrote:if there is any fluid in it you should be able to hear it if you tip the fork, they will still get compression from the spring without fluid in.

tipped them there now..........not a sound of anything!!!!!!!!!!!!!!!!! and no staining around the drain screws on either forks....... how much to get oil put in roughly in a shop...more importantly since they were operating with no oil would this do any damage to the forks inners?

thanks for the replies by the ya lads.

easy enough and cheap enough to do it yourself mate, fork oil from shop is less than £10, just take the bottom screws out and poor it in from there. cant remember exactly how much for each fork though.
Rough guess is about 110ml in each fork, i not done mine for a while now so could be a bit out.

Then when there back together do you preload (air pressure) i normally put 10psi in the forks for my weight its really good for cornering.
But make sure you use a foot pump, do not use a compressor as this will put too much in and pop your oil seals.

petrolhead19 wrote:easy enough and cheap enough to do it yourself mate, fork oil from shop is less than £10, just take the bottom screws out and poor it in from there. cant remember exactly how much for each fork though.
Rough guess is about 110ml in each fork, i not done mine for a while now so could be a bit out.

Then when there back together do you preload (air pressure) i normally put 10psi in the forks for my weight its really good for cornering.
But make sure you use a foot pump, do not use a compressor as this will put too much in and pop your oil seals.

sounds easy enough so.....what grade for oil should i use?.....the screws you are talking about, there is only one on each leg on the 23 .thats the one aint it?..i was worried about the preload as in what pressure but will try it myself........cheers for the replies...will do this over the weekend and let ye know the outcome...... thanks guys

If you tip the forks upside down and look down them you will see a bolt in the middle (allen key bolt)
Take that out and use a funnel to put the fluid in, and im pretty sure its 15w oil you need.

Good luck mate