Fork Knocking question

I am starting to notice a knocking/clunking noise which seems to be coming from the front forks when going over a sudden bump and am trying to track down where it is coming from. I have searched through the forums and found some similar problems but not sure if they exactly match my issue.

With the bike stopped and the front brake applied, I can reproduce the noise. If I just press down suddenly on the forks I can hear the noise or if I pull back on the forks slightly and then press down quickly, I can hear the noice (note, the noise occurs as soon as I press down, it isn't from the forks bottoming out). Now if I pull back the forks as far as possible so it is fully extended, pressing down quickly does not produce the noise.

I have checked all over the front can can not see or feel anything which is loose or making this noise.

I 'know' the fork oil and fork seals were replaced last year and within 5000 km's by the PO (I have the receipt with the date and km's from a reputable shop).

Any ideas where I should be looking to try and narrow down the noise. The forks feel fine and provide resistance in both directions and don't feel springy.

Thanks for any advice or help

 

How are the steering head bearings?

 

I will check the steering bearing as soon as my wife gets home (I need someone to sit on the back bike). I'll let you know what I find.

 

I've got the same thing going on with an XJ750J (my son's) I know the forks were apart but I have to get him out in the shop to do the same thing(sit on the bike) so I can check the bearings too.

 

Well my wife just got home. The steering wheel bearing seems fine based on the tests laid out in other threads (with the front wheel up, there is no movement/play, falls freely to both sides when given a slight nudge and it is completely free and even when moving the steering from lock to lock).

I had my wife listen/feel the forks, calipers, etc to see if she could feel the knocking. She said she can feel it slightly on the forks right below the dust seal, and slightly less lower down on the outer tube. I can't verify it myself as she can't reproduce the problem when she is sitting on the bike. Can there be something loose that might explain the problem?

Cheers

 

Depending on the arrangement of the 650 fork there could be two bushes. On other bikes I have had these wear causing the noise you are experiencing.

There could be an upper Bush (under the fork seal) and referred to in the Parts Ctalogue as a Metal Slide and another Bush again sometimes referred to as a Metal Slide (split-ring bushing on the bottom of the chrome tube). There is a lot of force (moment arm) acting on the fork as it (and the wheel) moves. Any play in either of these bushes will cause movement and noise, especially the ones on the bottom of the inner tube.

 

Thanks Kiwi,

I read that before in another thread on the forum, but looking at the manual for the front forks (as can be seen here XJ650RJ Front Forks), there is nothing called a bushing/metal slide and looking at the picture, I am not sure what part would be considered the bushing/metal slide. Any ideas.

Sorry, total noob here when it comes to bike terminolgy but am trying to learn as I go.

Cheers,

 

Your right, a quick look at parts catalogue in the link doesn't show any bushes (slide) but they must be there in some form otherwise the chrome inner would have no bearing surface other than the alloy outer casing to move against.

I was lead to believe by a friend that some of these bushes are not obtainable for particular models. I would suggest contacting Chacal and see what he knows.

The 750 forks I did had both, the split ring wasn't shown as an available part.

 

650 Maxim's only use a bushing iat the top of the lower tube (all models use a lower tube bushings). A few models use an upper (chrome) tube slider bushing also, but the 650 maxim is not one of them.

I don't have the correct ones for the 650 Maxim models in stock currently, as I am waiting for some to float on over from Japan, which then have to be cut down to the proper size (the parts biz ain't always as easy as it seems!).

Although, I'll have to opine that a loose or broken lower fork tube bushing is kind of hard to imagine, those suckers are in there TIGHT! They get worn and eventually need replacing, sure, but loose? Wow, that would be a first that I've seen.

On the other hand, if the damper rod had somehow gotten loose........it could make a knocking sound when you operate things as described. AS COULD A LOOSE BRAKE CALIPER.......