High speed wobble

[downerhouse]

Hi all, I've just joined this forum, but have had my 2015 Crossrunner for about 18 months.  As well as the CR, I have a 1984 RD350 YPVS and 1989 TZR125 YPVS.

I really like the CR, and wish I had changed to something like this years ago - for most of my riding life I've had ridiculous high powered sports bikes.  I enjoyed the sports bikes but actually prefer the more upright riding position, luggage, comfort, and spectacular engine on the VFR800X.

One problem though, is that at high speed (varies, but typically 110-120 mph+), the bike gets into a nasty speed wobble, which if I don't slow down threatens to turn into a slapper.  I have panniers and top box on.  I only weigh about 85kg, so am a bit stumped on how to fix it.  Tyre pressures are standard, the rear pre-load has been increased a little to compensate for pillion weight, but other than that is standard. 

The bike has only done 2000 miles so almost new.

Any thoughts and help appreciated.
Thanks

[Greenie]

Hi welcome to the forum 

A couple of things you could try,

1) Try a steering damper (if a suitable one exists)

2) Slow down a bit 

But seriously I haven't had mine above around 95 so haven't experienced the wobble you speak of.

Maybe different tyres would be worth a try too?

 

[reasty]

 
When you say standard tyre pressures do you mean the cr standard or as a lot of members have done and reverted to the vfr regular pressure of 42/36 (I think).
There's quite a few posts on it - might be worth doing a search.

Keep it upright

[v8guy]

Originally Posted by reasty

When you say standard tyre pressures do you mean the cr standard or as a lot of members have done and reverted to the vfr regular pressure of 42/36

My 2015 CR owner's manual says 42/36..

On the high-speed wobble front, I'd expect a bit of instability at that kind of speed with box and panniers fitted. Have you compared it to riding without the luggage?

Adding a bit of pre-load isn't going to compensate for the extra weight, mind.. have you tried upping the rebound damping too?

In general, I find the front end a bit wobbly when I let go of the bars.. never to the extent that I feel it's going to develop into a slapper, but it certainly ain't as stable as other bikes I've known.

[downerhouse]

No, I have not tried it without luggage.  I always need the luggage, so would like to understand the problem more.   Maybe it is a combination of me & aerodynamics.  I know what you mean about taking your hands of the bars - it's actually quite a surprise how much movement there is.

I'll take another look at pressures, and maybe have a word with my Honda dealer.  I can't find any steering dampers suitable for this bike, but seems major overkill anyway for a bike such as this.

Or I could slow down as the other reply suggested :-)

[v8guy]

Originally Posted by downerhouse

No, I have not tried it without luggage.  I always need the luggage, so would like to understand the problem more.   

Comparing with and without seems like a great way to set about that task. How much weight are you carrying in normal usage? I'd certainly expect tweaking the shock's damper to help if you're carrying a significant amount. Maybe try without luggage, with empty luggage, and then with normally laden luggage?

Originally Posted by downerhouse

Or I could slow down as the other reply suggested :-)

Always an option. 

[54K+]

I haven't experienced tho problem on my 2014 Cr at those speeds. My thoughts also would turn to the luggage as other adventure type bikes I've ridden have displayed the same sought of issue at high speed whilst carrying boxes ( and they were empty)
Most of my fastest riding is done with the top box in place but the panniers removed.

[Si Click]

The luggage is probably the issue.  Are you using the standard (relatively small) Honda top box, or a more useful larger one?

My 2011 CR is stable with a 46 litre Givi topbox, but my previous VFR800 FiX had a slight bar wobble from about 30 mph upwards.  Though as it was only noticeable if you fully removed pressure from the bars (took your hands off) it never actually became an issue. 

Set standard VFR800 tyre pressures (42/36) and then experiment with luggage - all off - top box only - panniers only.  If the top box is the issue could you borrow a smaller one and try that?

[downerhouse]

Yes, I have the standard Honda (small) topbox and Honda panniers. I'll try playing with pressures and will at some point try with luggage off. But if it is luggage would be disappointing as that is why I got the bike.

[Si Click]

Just checking my post, the tyre pressures are of course 36/42 (36 PSI Front and 42 PSI Rear or 2.5 kPa and 2.9 kPa)