Xs1100r

[TopCatGr58]

Hey TomB,

I remember having a similar discussion many years ago about this.

Here's a photo from the XS650 site showing a braced swingarm, along with a FB.



I did some bracing of my swingarm several years ago as well. I'll have to go upload the photos I have to my photobucket before I can post them. I used square tubing because I don't have a torch to be able to perform bending like that, and I thought that triangles would be stronger. It did seem to make the rear end stiffer, but I still have the hinge in the front of my frame/neck, along with my abnormally small trail due to my accident decade+ ago with a then unknown bent frame/neck! But I like the easier lighter steering, and I don't really need to go 100+ Mph much/often.

T.C.

[fredintoon]

- - - I still have the hinge in the front of my frame/neck, along with my abnormally small trail due to my accident decade+ ago with a then unknown bent frame/neck! But I like the easier lighter steering, and I don't really need to go 100+ Mph much/often.
T.C.

Hi TC,
as I remember those posts, your front end fix used over-length (+4"?) fork tubes.
The XS11 forks are flexy to start with and over-length tubes can only make them worse.

[motoman]

The Martini version, even though 'fugly' to most is still my favorite version of the XS11.
Couldn't get the pic to copy/paste, but here's some of its design history.

Way back, many years ago, a member here from across the pond had one he had posted pics of. Don't know if those were on the gusseted frame or not though.



In 1976, in an art-work feature on streamlining, designer John Mockett had been bemoaning the fact that the motorcycle fairings produced then, fell into two categories:

Dolphins: such as those from BMW and Dunstall, were good at cutting through the air but gave the rider little protection.

Snow ploughs: such as Vetter gave good protection but at the expense of performance due to the sheer size of them and the increased drag.

What was needed was a combination of the two and in 1977, John was contacted by Paul Butler from Yamaha's Design & Development department in Amsterdam.

He was willing to offer John 'free reign' in designing a fairing for an upcoming 1000cc plus tourer. The only stipulation Yamaha insisted upon was that the bike should remain as standard as possible.

Enlisting the help of sculptor Steve Furlonger and industrial designer Dave Weightman, they set to trying to design something which hadn't been done before. The power of the engine wasn't going to be a problem so the No.1 priority was going to be rider protection.

Enlisting the help of sculptor Steve Furlonger and industrial designer Dave Weightman, they set to trying to design something which hadn't been done before. The power of the engine wasn't going to be a problem so the No.1 priority was going to be rider protection.

"We relied on Steve as a 'maker' but he had more to offer than that. He had a sculptor's eye, that is an understanding of 3D form and all consuming energy. By the way in the last year two of the principles in this work have died; David Bean, the test rider, and Nieto-san the chief engineer.

Those guys were interested in pushing the envelope, not like today, copying existing models." - John Mockett (1999)

Work soon began in the wind-tunnel at Lanchester Polytechnic in Coventry on a 1/5th scale model of the new bike.

A one-piece fairing was on the cards at this stage but when a full size 'never to be run' prototype arrived, it soon became apparent that a rethink was needed because of the size of the arc drawn by the handlebars plus controls travelling from one lock to the other. An earlier 2 piece concept was adopted as this combined the potential benefits of a handlebar mounted screen with the aerodynamic stability of a compact frame mounted dolphin.

After more than 100 wind-tunnel tests, two prototypes were made, one for display at the Isle of Man T.T. and the other for the launch of the XS1100 at Senegal.

Initially, production was rumoured to have been by Harland & Wolff in Northern Ireland but it was Composite Laminate Products (CLP) of Durrington, Wiltshire who gained the contract.

It was available in 1979 as an accessory costing £360 and came in the two colours that the XS1100 was being produced in, namely Crystal Silver and Macho Maroon.

The finished fairing gave the bike:

Better lights with the Cibiè Tango 55 spotlights fitted into recesses at the base of the main body.

Two lockable, easy-access side pockets in the main body.

The ability to outdrag the standard XS11 (and the later 'S' model) due to the decreased drag of 15% and reduced front wheel lift of up to 32% (I'm talking from experience here)

Protection for the engine in accidents (and legs too)

[bikerphil]

The Martini version, even though 'fugly' to most is still my favorite version of the XS11.

[MPittma100]

Xs1100r

It is similar to a 81 MNS but with the rare swirly 17" rear rim and no gold trim. Nice lookin' bike.

Same wheel as the 1981LH Midnight Special.

[bikerphil]

MNS are 16" rear, fronts look the same 19".

[Prisoner6]

Same wheel as the 1981LH Midnight Special.

No, they're both the same style wheel (read "swirly"), but the R model has a 17" rear wheel and

the '81 Midnight has a 16" rear wheel.

[MPittma100]

Welding

Hi T.C., if one was to add the gussets and bracing, what would be the optimum weld procedure of choice ?

In sanctioned racing rules such as NHRA, all welding on round chassis tubing has to be tig welded. There must be something to that.

I can't imagine needing the frame gussets on the R in Europe/Asia and not in the US has a whole lot to do with anything other than government requirements. I don't believe they would be useful for anything other than in a crash - and they might make crash results worse. JMHO

Example: European Mercedes Benz cars cannot be sold here in the states unless they are structurally upgraded to US requirements. One step of the upgrade is adding an additional steel brace inside of the doors.

Mike

[Eveready1100]

I don't believe they would be useful for anything other than in a crash

Mike, it's got nothing to do with crash reinforcing etc. They're there to make the frame stiffer for better handling - no more.

As Tom has indicated with his examples, by him properly securing the frame tubing to the steering head and other frame mods with substantial weight reduction on his "ratbike" (more a work of art than a rat, by any standard), and comparing it with both a Stock E model and a Sport (5K7 /5N5), he's demonstrated that there is a definite advantage (at speed) to having the frames stiffer.
Have a look at any of the 80's era superbikes and they've all got substantial bracing around different areas of the frame.
I'm also pretty sure that the thinking behind the lower cradle bracing was an attempt to stiffen this area of the frame without resorting to the often used method of fitting solid engine mounts to make the engine a stressed member of the frame. It does work extremely well, but increased vibration during day to day riding probably wouldn't have been a big selling point for the average customer.

[TopCatGr58]

Hey Phil,

Thanks for the nice photo, I had never had a real good look at the martini, didn't realize that it was a 2 piece unit, handlebar as well as frame mounted!

Okay, finally got around to uploading the other photos of my swingarm bracing to Photobucket. The welds are pretty, but you can see what I did. I tried to make the sections as short as possible=stiffer, as well as clearance for frame, and on the sideview they make a triangle, the strongest geometric shape from what I've been told!




These shots are of course with it mounted, showing the "lack" of wheel/tire clearance, but also clearance of other frame structures when mounted.







And it doesn't stick out/down that far so that it doesn't really detract from the STOCK look, since it's mostly hiding behind the footpeg mounts, and exhaust and such.

T.C.

PS, a couple of shots looking down the swingarm with the shaft in relative position to show the lack of space between the wheel/tire indent and the shaft, for those looking to mod the swingarm cutout to allow a little more room for a wider tire!?

[Schming]

The "hinge"?? yes the hinge does appear tamed on the XS1100R.

I own two Standards, one with steering head braced, frame braced, monoshocked rear end, bigger forks, massively lightened, and I own a stock Standard so I have some pretty good comparisons.

I hear what you're saying about the shaft effect and cornering, what I use as a measure is the high speed straight line weave, at 130mph the stock Standard could start to weave, the monoshocked bike doesn't and the stock XS1100R doesn't, I can definitely feel the difference. This is all subject to getting your forks and rear shocks in top condition, when I originally rebuilt my Sport it handled crap due to the rear shocks, I now use Koni's.

Marty, all the XS1100R and XS1100S (Sport) models had gold wheels, and gold tank, seat and panel badges, that was all though, not like the MNS's which had lots of gold trim. I have XJ1100 wheels on my Sport, I like the tubeless wheels and also like the black colour rather than the gold.

Marty's photo shows the cross tube bracing and also the underframe brace mounts, there is a large heavy brace bolted to this bracket, I have the brace but can't use it with the Kerker, it goes outside of the stock exhaust 2+3 pipes but won't fit over the Kerker collector.

Heres a swing arm with decent bracing one of the UK lads has done

Hi Tom, would you have a pic or some dimensions of the underframe brace ?
Koni is now Ikon and I did some perusing on thier site which has a lot to offer.
That swingarm looks good but IMHO it could use a few more struts along the length and one in each corner.

Hey Phil,

Thanks for the nice photo, I had never had a real good look at the martini, didn't realize that it was a 2 piece unit, handlebar as well as frame mounted!

Okay, finally got around to uploading the other photos of my swingarm bracing to Photobucket. The welds are pretty, but you can see what I did. I tried to make the sections as short as possible=stiffer, as well as clearance for frame, and on the sideview they make a triangle, the strongest geometric shape from what I've been told!




These shots are of course with it mounted, showing the "lack" of wheel/tire clearance, but also clearance of other frame structures when mounted.







And it doesn't stick out/down that far so that it doesn't really detract from the STOCK look, since it's mostly hiding behind the footpeg mounts, and exhaust and such.

T.C.

PS, a couple of shots looking down the swingarm with the shaft in relative position to show the lack of space between the wheel/tire indent and the shaft, for those looking to mod the swingarm cutout to allow a little more room for a wider tire!?

The swingarm mod is worth considering and is completely reversible.
I googled swingarm bracing and there is some good info out there
Did you get a measurement of the space between the shaft and the inside of the SA ?

[TomB]

Here ya go Schming





And don't forget a point Errol (Eveready1100) made about the XS1100R's frame strength, the frame tubes were made of a slightly heavier gauge tube.

That swingarm looks good but IMHO it could use a few more struts along the length and one in each corner.

Yeah true, but I like the simplicity of it, its a beautiful thing that will give a huge amount of added strength.

The thinking behind the braced swing arm is to keep both sides of the thing fixed together, using twin shocks which may be unmatched can cause the rear wheel to pitch about with flex in the swing arm. Another way is to use a single shock and triangulation to the swing arm.
I also like the idea of mods that are reversable, I altered a swing arm to do my monoshock with even less changes (Yes the frame is heavily modded but it was scrap before I started anyway due to a major collision).

[Schming]

Thanxs for the pic of the brace, Tom.
Gives me a better idea of what I might be able to build.
I may have to solid mount the engine if the non-stock exhaust won't allow the brace to be fitted properly.

In your pic with the mono shock modded frame, I can't see how the swing arm still wouldn't flex under laterel force applied in a turn at speed with the final drive differential torque also.

I can see the balance you gained, with the mono shock, attaching the brace at the shock mounts. If the "U" bar brace was welded with strategically placed struts to the SA then IMHO T!Ts

The issue I see with the stock SA under bracing is final drive being part of the SA. Bracing, along the length should run from the SA pivot point to the axle equally on both sides.
The XS11's shaft side SA weld point is only half way to the axle.
Some tricky fabrication will be necessary to extend the bracing on the shaft side or just brace equally on both sides at a greater angle for maximum rigidity.

[TomB]

Thanxs for the pic of the brace, Tom.
In your pic with the mono shock modded frame, I can't see how the swing arm still wouldn't flex under laterel force applied in a turn at speed with the final drive differential torque also.

A bit like an anti roll bar on car suspension, on that one wheel may want to go up because its pushed up, the anti roll bar will pull up the opposite side. I simply used the original shock mounts on both sides.

[Schming]

T.C.

I've done an extensive search throughout the site and can't seem to find a close up pic of the XJ front calipers.

Looks like to me that the XJ forks are used on the R's all except for the air balance tube and the dialable damping.

Are the XJ's forks 37mm ? If so I'd like to use them on my SF to facilitate the use of better calipers with custom fabbed brackets.

I know you, TC, have made custom brackets for your Special forks and I contemplated that route but looking at the R's forks I noticed that the calipers mount just like the XJ's and IMHO would be easier to adapt a later model caliper as you have.

Using the XJ's forks would give me balanced air assist and on the fly damping . . . if they fit the SF's TT.