Any Suspension Gurus Out There?

[af1-windy]

The issue I'm having is a speed related problem. The bike gets into a head shake around the 120mph mark..

Firstly, I should say that anywhere under 3 figures the bike handles fantastically, as Antares will hopefully attest to, as seen yesterday on a 6 miles stretch of road we're both familiar with, a great range of bends in a flat landscape, with uninterrupted views and light to no traffic, so the road can be used curb to curb, or to be literal, grass verge to grass verge. perfect for testing bike and rider. 

Secondly, acceleration isn't an issue through the gears, so I don't think the problem is caused by the front going light, unless it's a combination of going light and aerodynamics coming into play at higher speeds. It happens both on the straight and long sweepers, if it's on the straight and I shut of completely, it shakes as the front end loads up with the slowing down.

That's it, any help, insight, tips etc would be greatly appreciated.

I know the obvious thing is to stay below 120mph.. but! I have spent many years getting to a level of riding that I can enjoy long sweepers into 3 figures, in fact I go out hunting them down, still one of the best feelings ever, speed, lean angle, accelerating hard out, sensing the rear tyre searching for grip.. I f**king love it.. Is that wrong at 63 years young 

  windy

[Salish1000]

I'm not a suspension guru by any stretch, but I love your post for how you are enjoying yourself. Would think the steering damper is my first thought. All other things being within spec I can't see why anything else would cause the wobble. Modifications of any type like windscreen or crash bars or any of that stuff can impact the dynamics. Fascinating how MotoGP and now even street bikes have those fins on the front to hold them down.

Keep riding fast brother, when safe to do so!

[wessie]

Before you go blaming the suspension, you need to eliminate problems with the tyres and wheels.

This is the default response from a friend of mine who has done endurance racing, IOMTT, Manx GP and Classic TT.

[Antares]

I'll cut in here since ha hasn't already, new tyres were fitted since, steering damper changed too both did nothing. This is definitely a geometry / aero issue, especially at the sort of speeds mentioned. I had very similar weaves with top box on when I had brand new Contis on my XR, now windy's XR is far from stock and I can see a lot of things that may cause the disturbance, will probably need to eliminate things as they go.

[capt cf]

Have you looked at your downforce package?  You might want to consider adding a tail fin if you haven't already.  Also, check your winglets to make sure they weren't damaged when Marquez clipped you while making an aggressive inside pass.

[Antares]

Originally Posted by capt cf

Have you looked at your downforce package?  You might want to consider adding a tail fin if you haven't already.  Also, check your winglets to make sure they weren't damaged when Marquez clipped you while making an aggressive inside pass.

 

Jokes aside he has wind deflectors and extended handguards, maybe the combination of both could be upsetting something, also just a whole lot of stuff on the bike and it's also a factory low. My Normal height XR even when it was new to me with nothing on it, just an MRA screen was "just about" stable enough to not cause concern at 120+ but you could tell it's not on rails like my new 1290 GT is.

Aero does make a huge difference in stability, I had a 2003 XT600E Supermoto converted, cut front mudguard short, at 90+ front end would start to raise and walk like nobody's business as air caught under  the fender and forced it up, replaced with a stocker, despite being longer and floppier, it was way better.  The XR is a very tall and vertical bike even lowered, lot of potential for some air to catch on the front.

That said it could obviously be a host of other things too

EDIT: actually I have a 3D printer, maybe I should make some bolt on M1000RR style winglets... now there is a thought 

[garyculb]

Originally Posted by af1-windy

The issue I'm having is a speed related problem. The bike gets into a head shake around the 120mph mark..

Firstly, I should say that anywhere under 3 figures the bike handles fantastically, as Antares will hopefully attest to, as seen yesterday on a 6 miles stretch of road we're both familiar with, a great range of bends in a flat landscape, with uninterrupted views and light to no traffic, so the road can be used curb to curb, or to be literal, grass verge to grass verge. perfect for testing bike and rider. 

Secondly, acceleration isn't an issue through the gears, so I don't think the problem is caused by the front going light, unless it's a combination of going light and aerodynamics coming into play at higher speeds. It happens both on the straight and long sweepers, if it's on the straight and I shut of completely, it shakes as the front end loads up with the slowing down.

That's it, any help, insight, tips etc would be greatly appreciated.

I know the obvious thing is to stay below 120mph.. but! I have spent many years getting to a level of riding that I can enjoy long sweepers into 3 figures, in fact I go out hunting them down, still one of the best feelings ever, speed, lean angle, accelerating hard out, sensing the rear tyre searching for grip.. I f**king love it.. Is that wrong at 63 years young 

  windy

 This can be a tough one. The Gen 2 XR does not float down the road like the KTM GT. Got up to 137MPH on the GT with only wind issues.

 The OEM Gen 2 XR Roars at 110MPH and then, seemed to rise up. Got a Gustafsson Windscreen (https://bikescreen.com/products/bmw-s1000xr-2020 ) that helped allot. Have gotten up to 125MPH on the highway with new DID ZVMX chain & 17/42 sprockets (https://www.s1000rrforum.com/threads/gen-2-xr-525-42t-rear-sprocket-change.249608/ ). Ride was much more stable. XR seemed to have more to give if I wanted.

 Consider taking wessie's advise- Check your tires and make sure they are not cupped/old. Yes, I have a Hyperpro Stearing dampner (https://www.s1000rrforum.com/threads/2020-s1000xr-steering-damper.248995/page-2 ) but, do not know if that would be your issue.

Best,

Doc

[wessie]

there's another old maxim, in the face of unresolved problems, remove any "improvements" and take the bike back to stock...

[Salish1000]

It must be said with some jest that while the KTM 1290 GT might feel more stable at high speeds, that's only if you can ignore the flashing warning lights that plague you and the darn thing is running and not parked at the shop! If we really wanted max stability at highest speeds, let's admit we'd be on a Busa or ZX14. Even a Concours 14 or FJR. I've been on my Connie doing north of 120mph and it felt like I was doing 30mph. No difference other than crap flying by quickly. What the XR gives in being nimble it must take away somewhere.

[Antares]

Originally Posted by Salish1000

It must be said with some jest that while the KTM 1290 GT might feel more stable at high speeds, that's only if you can ignore the flashing warning lights that plague you and the darn thing is running and not parked at the shop! If we really wanted max stability at highest speeds, let's admit we'd be on a Busa or ZX14. Even a Concours 14 or FJR. I've been on my Connie doing north of 120mph and it felt like I was doing 30mph. No difference other than crap flying by quickly. What the XR gives in being nimble it must take away somewhere.

Hey!!!

In the 1500 miles I put on mine yet I only had 2 "General Failure, 1 ECU Failure and 1 Random "check engine light"