Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.

Shakey head

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hobbes748
Hyper Viper
Hyper Viper

Posts : 44

Shakey head

Post by hobbes748 on Wed 01 Oct 2014, 12:48 pm

Hey guys

I’ve been running a CB as a commuter for almost a year now and it’s been great. I know it’s no sports bike but I have noticed that on the odd occasion when I do give it a bit of a tickle on the twisties it shakes its head a fair bit when you’re trying to quickly flip flop from one side to the other. At 55-60 it’s fine but anything quicker than that at a decent lean angle and it’s quite un-nerving.

I serviced the forks 2 months ago (cleaned the internals, new seals, and replaced the oil with slightly heavier SAE15W) but that made no difference, the tyres are BT45’s at 36/40 and I can’t see anything obviously wrong with the bike – so could this just be me approaching the natural limit of the bike (in standard trim) or could there be something else afoot?

If this is approaching the limit of the bike in my hands (although I’m sure a club racer could get more out of it) then that’s fine, at least I know where it is now. I purchased it as a commuter so I’m not interested in increasing either the handling or performance – I’ve already got an out and out sports bike for silly days. But if this is an indicator of something fishy going on then I’d like to get to the bottom of it.

Thanks
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stormbringer
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Location : Aarhus, Denmark

Re: Shakey head

Post by stormbringer on Wed 01 Oct 2014, 1:15 pm

Steering stem bearings? Swinging arm bearings? Wheel bearings?

Not that I have much reference material to build upon. Basically guessing...
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hobbes748
Hyper Viper
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Posts : 44

Re: Shakey head

Post by hobbes748 on Wed 01 Oct 2014, 2:17 pm

stormbringer wrote:Steering stem bearings? Swinging arm bearings? Wheel bearings?

Not that I have much reference material to build upon. Basically guessing...

Shouldn't be the head bearings as they were replaced this year. As for the rest - I'll look into it.

I had a bit of a moan about it to a fellow biker I met while out for a blast on the other bike. He suggested it could be the forks topping out, but I've no experience of this happening on any other bike I've had so I don't know how it would feel. Could it be this?
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Beresford
the 900
the 900

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Location : not that far from Kirkistown

Re: Shakey head

Post by Beresford on Wed 01 Oct 2014, 6:02 pm

If this is happening when you are hard on it, it could be due to weight transfer rearwards causing the steering to go light and shakey. I notice this on my bike because as I'm on the large size, I'm already sitting about 6" further rearwards.

If you really lean forward as you are accelerating, does that reduce the shaking tendency ?
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Tricky.
the 900
the 900

Posts : 721
Location : Derby

Re: Shakey head

Post by Tricky. on Wed 01 Oct 2014, 6:18 pm

maybe stiffen your rear shocks a little.

muttley1
the 900
the 900

Posts : 752

Re: Shakey head

Post by muttley1 on Wed 01 Oct 2014, 6:36 pm

Seconded, more preload on the back so slightly more weight on the front. Might be worth making one definite cornering movement (go in deep and countersteer) then drive out rather than let the bike bounce its way round on a constant throttle.

atb

muttley1
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hobbes748
Hyper Viper
Hyper Viper

Posts : 44

Re: Shakey head

Post by hobbes748 on Thu 02 Oct 2014, 8:11 am

Thanks for all the suggestions guys. I can’t work out how to multiple quote, so I’ll just do it this way instead…

Beresford - I’m fairly average size (6ft, 11.5 stone) and I think I do tend to keep my weight up the front, but I do also weight the pegs quite heavily on this bike as I feel it makes a marked difference (especially in the damp). I’ll maybe try weighting less and concentrate on getting a bit more over the front end.

Tricky – I’ve only got one more click of adjustment on the back, but I’ll give it a try none the less.

Muttley – The issue isn’t so much with holding it in the corner, it’s the transition between getting it from a heavy left lean to a heavy right (or vice versa) quickly. It’s just that second that’s the prob. It gives me the willies!
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ashcroc
the 900
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Posts : 1505
Location : London

Re: Shakey head

Post by ashcroc on Thu 02 Oct 2014, 10:45 am

You could try dropping the headstock on the forks 10 or 15 mil. It'll throw your weight forward a bit more & can help cornering.
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hobbes748
Hyper Viper
Hyper Viper

Posts : 44

Re: Shakey head

Post by hobbes748 on Thu 02 Oct 2014, 12:00 pm

ashcroc wrote:You could try dropping the headstock on the forks 10 or 15 mil. It'll throw your weight forward a bit more & can help cornering.

Wouldn't that just make it twitchier in a straight line instead?

The cornering isn't the issue. Hard left - no problem. Hard right - no problem either. It's linking these two together quickly (as you would when you go through a big chicaine or an 'S') is when it all goes wrong. When you haul it up out out the left it shakes its head all the way over to the right and then settles down again (and vice-versa of course). It's a horrible feeling.

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Pukka
Crotch Rocketuer
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Posts : 34
Location : Woking, Surrey

Re: Shakey head

Post by Pukka on Thu 02 Oct 2014, 1:57 pm

Hows the front tyre wearing? When my last tyre (a BT45) was nearing the end of its life the profile took more of a triangular shape. Had a similar head shaking problem during fast direction changes which has gone away since changing the tyre.
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hobbes748
Hyper Viper
Hyper Viper

Posts : 44

Re: Shakey head

Post by hobbes748 on Thu 02 Oct 2014, 3:13 pm

Pukka wrote:Hows the front tyre wearing? When my last tyre (a BT45) was nearing the end of its life the profile took more of a triangular shape. Had a similar head shaking problem during fast direction changes which has gone away since changing the tyre.

Oooh.... I've not looked. I'll have a look and report back later. Thanks.
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GlenAnderson
Laser Shark
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Posts : 193
Location : Dover

Re: Shakey head

Post by GlenAnderson on Fri 03 Oct 2014, 12:50 am

I'll second the tyre possibility. My old BMW R100RS was very sensitive to tyre wear, and a slight shake of the bars was the first sign; getting steadily worse as the tyre neared the end of it's life.


Last edited by GlenAnderson on Sun 05 Oct 2014, 1:38 am; edited 1 time in total (Reason for editing : spelling fail...)
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Gonzumzum
the 900
the 900

Posts : 296

Re: Shakey head

Post by Gonzumzum on Fri 03 Oct 2014, 10:10 am

Aren´t the "shakes" natural...."charisma"? Smile

If this was a Ducati, people would say it´s the bike personality bla bla bla....
Now that it´s a Honda, it should do everything like it´s in the books....
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stormbringer
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Location : Aarhus, Denmark

Re: Shakey head

Post by stormbringer on Fri 03 Oct 2014, 10:33 am

Gonzumzum wrote:Now that it´s a Honda, it should do everything like it´s in the books....

Haha Smile
If you'd bought a Ducati, you'd have spent at least ten times as much of your hard-earned money and would most likely be ten times less prone to admitting flaws/faults/bugs.

You know what they say at Microsoft when something craps out? "It's not a bug - it's a feature!"

So, Ducatis have 'charisma'. Bah...

If whatever the bike does gives you the willies, it's bad and must be addressed.
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hobbes748
Hyper Viper
Hyper Viper

Posts : 44

Re: Shakey head

Post by hobbes748 on Sat 04 Oct 2014, 10:17 am

stormbringer wrote:
Gonzumzum wrote:Now that it´s a Honda, it should do everything like it´s in the books....

Haha Smile
If you'd bought a Ducati, you'd have spent at least ten times as much of your hard-earned money and would most likely be ten times less prone to admitting flaws/faults/bugs.

You know what they say at Microsoft when something craps out? "It's not a bug - it's a feature!"

So, Ducatis have 'charisma'. Bah...

If whatever the bike does gives you the willies, it's bad and must be addressed.

Easy tigers!  Wink As my username suggests, my other bike is a Ducati.  I think it genuinely drips with charisma (and not just using that word to cover up for issues), which is probably why I've still got it after 13 years, and in that time I've actually had fewer issues/niggles/bother with it than I've had from my CB over the last 12 months (and the Ducati has the higher mileage too).  I'll admit that working on them is mostly an access nightmare (other than the clutch which literally takes 5-10 minutes to replace - or the back wheel which takes seconds).   But if you're referring to more modern Ducatis then crack on!  I don't like them much either.

As for the willies, I think I've cracked it with all your help.  Body position!  Boy, you have to throw a lot more of your weight over the front that I'm normally used to, but it had the desired effect of no nasty wobbles.

Thanks again folks.

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