636 Forks Clonk

[crash harry]

I have a puzzeling issue with the forks in the 6R (2006 ZX636).

The forks clonk. I'm pretty sure it's coming from the forks, I can feel it in the fork tubes, triple clamps, handlebars, etc. When you compress the forks no problem. When you release them there is a clonk. It can be done at rest by pushing down on the bars and releasing them.

I've checked the steering head bearing, it's tight as a tight thing.
I've tried playing with the suspension adjustments and it makes no difference.
Triple clamps are tight.

Does anyone know if this is an issue or just normal? It's not a loud clonk but I can sometimes hear it on the move and it's a little annoying. If it's something they all do then I'll just harden up and ignore it, but it's not something I've heard a bike do before.

[flyingcrocodile46]

I'd go back to the steering bearings. I found almost identical symptoms ended up coming down to the steering bearings although I couldn't seem to get any movement out of them... until I took the wheel off and checked again rocking the forks back and forth the slop was then very pronounced. Dunno why, maybe I just didn't check properly the first and second times?

Not sure how you have gone about checking them but you need to unload the front end with the wheel a couple of inches clear of the ground so you can push and pull the forks back and forth (any movement tighten or replace) and try rotating the bars side to side gently to feel for any notching in the bearings (particularly after tightening) if you feel a hint of notching (usually in the middle) replace the bearings and seats. You said they are tight. Check they aren't too tight. If you centre the bars then give a tiny nudge one way or the other to get them started, they should fall freely to the stops and bounce back a bit.

Otherwise I have heard that fork wear can lead to similar clunking. Is there any play in the discs?

[T.W.R]

If you centre the bars then give a tiny nudge one way or the other to get them started, they should fall freely to the stops and bounce back a bit.

And doing that would have them too loose in the headstock. Adjusting the headstock bearings by that means there should be the smallest amount of resistance when the wheel is let fall to either side. If they're set up that the fall freely and slightly bounce off the stops then once the wieght of the bike loads the bearings up again with the wheel on the ground the free play is way too much and the knock will be back in very short time or worse than when you started

Quickest check for sloppy headstock bearings is to have the bike on the sidestand, stand in front of the bike, grab the handlebars & front brake, balance the bike upright, lodge the front wheel between your legs and try pulling the bars towards you.

[flyingcrocodile46]

Geeeze, I knew I shouldn't have edited it. I removed 'tiny' from before 'bit' as I remembered that someone had advised me that it was ok for a bounce back up to half an inch and I figured that perhaps tiny was misleading in that case.
Last time I listen to them.

And doing that would have them too loose in the headstock. Adjusting the headstock bearings by that means there should be the smallest amount of resistance when the wheel is let fall to either side. If they're set up that the fall freely and slightly bounce off the stops then once the wieght of the bike loads the bearings up again with the wheel on the ground the free play is way too much and the knock will be back in very short time or worse than when you started

Quickest check for sloppy headstock bearings is to have the bike on the sidestand, stand in front of the bike, grab the handlebars & front brake, balance the bike upright, lodge the front wheel between your legs and try pulling the bars towards you.