Hi all,

I've been using the bird again for a few weeks now and although it seems to run fine, it still needs some cosmetic work. Anyway, that's now why I'm posting this:

Last night I was riding home from KM practice and decided to let go of the handlebars on a straight and empty part of the road and just stretch for a second. I can easily do this (and do regularly) on the F4 with confidence so I didn't expect the following; I let go of the bars for just a second or two and a headshake was developing. It surprised me so much that all I could think of was "WTF, where did that come from?!?!" I let go going perhaps around 30/35 mph so it was nothing crazy. I'm quite sure that if I had been a bit later the headshake would have become a tankslapper, or at least a violent eough headshake.

I know for a fact that my right clipon was violently smashed into the tank because my tank is dented, my clip on was ever so slightly off alignment and the little tab on the yoke that stop the handlebars from full lock to full lock looked slightly damaged/dented. After the crash I eyeballed the forks and they seemed to be straight from every direction. After the headshake I was looking at my top yoke when going straight and it was ever so slightly tweaked to the right. This is probably why the right clipon comes so close to the tank at full lock but full lock to the left gives me more space for my hand.

Is it possible that the fall didn't actually bend the forks but it tweaked the positioning of the yoke assembly/forks so it's ever so slightly out of alignment? I ride around with one hand all the time and never noticed it on the Bird before. Perhaps one of the front forks lost some oil? Unfortunately I didn't do the 'look mommy, no hands' when I just got the bird so I don't know if it was there already. Everything looked ok back then. If I ride with one hand and grab the handlebar very lighty (basically not touching it), the shake doesn't seem to develop although in all fairness.. I'm a bit afraid to properly test it at more speed.

Any thoughts?

(I'll try to get a pic so you can all see that the top yoke is only very slightly tweaked.)

I just did some more researching and it seems that some Bird owners have experienced a slightly wobble this due to the Topbox (which I have on it)...

I also replaced the rim a while back since the old one was dented and have been using the front tyre that came on the new rim. Perhaps it's not quite balanced? I am getting a new front tyre quite soon anyway because I'm not sure how old this one is... It seems to work for now but feel less confident in rain. Some people have said they didn't have it when they removed the topbox and also when carrying a passenger. I'm going to test it on the way home since I have a passenger on my commute and see it It's still there. I pretty much always have a passenger on this bike so maybe that's why I haven't noticed it yet? Then again, I don't feel like I was going fast enough last night for the topbox to really make a difference..

I also have a slight head knock and this might be caused by several things.. Perhaps the bearings are done, perhaps the top nut needs to be torqued. I feel it when braking slightly harder and when compressing the forks standing still. Any thoughts on this? I did a good check up when I first saw the bike and I didn't notice anything back them either.

All of the above doesn't change the fact that my top yoke seems to be slightly out of alignment though.....

 

I have a 2002 CBR 600F1 and have just come home from a 280 mile trip from my home town to Plymouth. I let go of the handlebars many times during my ride home with no twitching or any movement at all and I had a top box which had quite a bit of weight in it. I'm more inclined to think the forks aren't set in the yokes properly and the head bearings are either too tight or too loose. From your symptoms I'd guess they are a touch too loose. You could try undoing all the fastening on the yokes, bouncing the front end up and down a few times, then locking everything up again. This usually lines the fork legs and yokes up properly and may cure your problem. The steering head bearings may need tightening up, but be very careful not to overtighten them as you will damage the bearings! The adjusting nut only needs to be turned a fraction to take out any play in them. A good way to check for play is too squat down in front of the bike with the front wheel off the ground (if you don't have a centre stand get help to lift the front up and support it under the engine), take hold of both lower fork legs and try to rock them back and forth to see if you can detect any play which will be evident as you do this. Also turn the forks from side to side to see if you can detect any stiffness in the bearings, indicating they are too tight. The offset yoke should set itself into the correct position during the first of my suggestions providing the upper fork legs can move within the yoke.

 

I have seen forks take an incredible impact & still test out ok. Then again, I've seen forks take what seemed to be a minor hit & be way out of spec. I would want to pull the forks & test the run-out to see if they still fall into factory spec. While doing that, I'd check the head bearings as stated above.

 

While the tire could be a symptom & should also be checked, a thorough & complete front end check couldn't hurt & really should be done. As easy as it is to pull forks, there's really no reason not to do it.

OP, you seem to have a good knowledge of bike handling & possible causes. So, pull that front wheel/tire & check it, pull forks & test run-out, & check head bearings/steering stem.

Good luck.