Headshake causing a headshake...

Hi all,

This afternoon, Lisa and I loaded up the XX and rode south down to Nowra.
As many of us do, I often sit up and drop the arms on a roll down a hill,
fully releasing the bars and relaxing.

Today, we were cruising down a hill in a bit of traffic at about 60 and I
did the above and within seconds, the front started to shake badly and
almost went into a tankslapper. Until I released the bars, there was no
hint of front end vibration or wobble. To me, this rules out throwing a
weight. I tested this a few more times and it did start to shake a little
at the lower speeds, but seemed OK at highway speeds. While holding the
bars, the bike was perfect all afternoon.

We were a little loaded and the topbox was quite a bit heavier than usual
(~7kg), so I thought that this could have lightened the front end a bit
(though weakened the rake). Tyre pressures are right, tyres are perfect and
wheels have just been stringlined.

Should I have the head bearings looked at? What's likely to cause this?
Clearly it would be easy to suggest never releasing the bars (I've been
doing it for years on pushbikes/mcycles and it's quite a habit) but I'm more
interested in seeing why it's suddenly started. Tomorrow I'll try it with
no gear or wife on board and will pass on any findings.

Anyway, thanks if anyone has any ideas and I'll keep you posted.

Cheers,
Dave ZZR600 => ST2 (stolen) => '03 XX
P.S. Our spin through the National Park had no (zip, none, zero...) cars;
Macquarie Pass - a couple of cars that we caught pretty much at the pie
shop, so completely unhindered; Fitzroy Falls - again, no cars at all;
Kangaroo Valley to Nowra - caught a line of about 20 cars following a truck
heading up to the top of Cambewarra Mtn and passed the lot of them on the
final straight (overtaking zone) before the top - so the whole mountain was
again devoid of vehicles as far as we were concerned. And some people have
suggested (ludicrously) that we would never need the power of the XX.
Awesome! Lisa *didn't* even kill me, despite our speed delving deep into
spanking territory.... ooohhhh - whooo'se yer daddy.

 

On 14/11/03 8:43 PM, in article
bp284m$1k1v6j$-berlin.de, "Dave Ello"
<> decided to come out from under the bed
and slurred:

Oh dear, its time to split the cases! Shes rooted!

Hammo

 

Leave my wife out of this you cheeky bastard. She'll kill you...

Actually - you're probably right - she's got 4 months and 7000 clicks on her
now so probably ready for a decent probing - and same for the bike.

Cheers,
Dave ZZR600 => ST2 (stolen) => '03 XX

 

Mine does the same, between about 70 and 80kph, only when the back is loaded
up with luggage.

Nev..
'03 ZX12R
'02 CBR1100XX

 

Thanks Nev,

Hmmm - good to know. The only thing that makes today different was that the
topbox was pretty heavily loaded. We are often much heavier than today -
but weight more centrally loaded. I usually put the heavy stuff in the
tankbag or bottom of the panniers but we had a big item to take (I'm not
referring to Lisa's bum - we have to take that all the time...).

Got a bit of a shock - we were in traffic at the time and the damned thing
began the death oscillations! Not joyous but all is well that ends well.

Cheers,
Dave ZZR600 => ST2 (stolen) => '03 XX

 

Maybe Lisa is bulking up

 

I'll be interested to here where you get to on this one Dave as I've noticed
similar attitude. Once I had hands just off bars to get circulation again
and the front started to waggle. Caused a bit of concern but it only
happened at low speed and decellerating. Haven't persued it further yet.

 

Dave,

You might recall me alerting you to this potential problem when you first
got the Budgie as I had experienced it on mine as well.

In my case, it usually occurred whilst decreasing speed from around 80kph
through to about 60kph. It tended to be worse when the front tyre was
showing some wear and when I was carrying a pillion. I suspect that the Givi
panniers (and contents) are exacerbating it in your case.

The "solution" is to replace the roller steering head bearings with tapered
bearings. It doesn't actually solve the problem but effectively masks it and
cost around $200. Well worth the investment IMHO.

Hope this helps
Peter

 

How does the change from roller to tapered solve this problem? I can
understand that if they are worn, or not torqued correctly. I know you said
it masks it, isn't that an admission that its just a band-aid solution?

Cheers

Hammo

 

Take it out to Frank Pons ans get your suspension sorted That'l do it! I
turned my 954 from tank slappin bitch into a stable table. Oooooooooh yeh!

Cam
'03 954 (solid as a rock now!)

 

I'd be betting $10 that's the cause - you need sufficient weight on the front to
keep it stable hands off - it's why TRX's are prone to it. Did you up your
preload ? Adding on some more preload when you add additional weight is a good
idea and will stop the back squatting and hence extra bike weight transferring
to the rear.

JL

 

First thought:
suspension ( right preload for the weight at back?)
Second:
tyres, most precisely: the front.
had similar on the Bandit12 (after the firsat 3000km) until I changed to a
Metz Z4, which took the shakes out completely, right through the life of the
tyre.

my 0.02c
cheers
pete

 

Hi Dave,

Maybe a bit more preload on the rear to shift weight forward a little ? Less
weight in the top box? How warn are the tyres

and finally, I wouldnt really worry about it, bikes the size of the XX and
Zed are a delicate balance between mundane cruiser handling and sports like
nimbleness - the trade off is they are vunerable to headshake under less
ideal weight distribution.

Nothing to really worry about - just keep the hands on the bars if you cant
dial it out

 

Just what does this mean? My Beemers need an extra 10-15% air in the rear
with a pillion, and another 10-15% with a decent load, or the rear end
wallows everywhere and the front shakes frantically...

Keep us posted!

Magic!

Gary

 

Hmmm - good to know. The only thing that makes today different was that the topbox was pretty heavily loaded.

Unload the top box leave the rest as it is and ride it again, see if
thats what it was, or not..

 

You wouldnt be Rich's with the hirebus mate from shitney that moved to
melbourne??

 

Hows this for fscked up. Whenever I put on my jacket I get headshake
outya the CBR because the jacket acts like a parachute and causes my
arms to shake the bike!

 

Too much weight on the rear.
(no dig at the missus either.)

 

You ride hands-free in traffic? You're a devil, Dave.

 

<snip>

Blinkers and a shadow-roll often settles flighty steeds down.