Raising the rear of the 1100 Katana without changing the shocks

[John Kat]

I'd like to raise the rear of my 1100 Kat while keeping my current shocks.
There is a kit in Japan that appears to do this by lowering the shock top mount:

https://japan.webike.net/products/1484104.html

I believe it could be done rather easily without spending that much money?
Has anyone done this before?

[posplayr]

U bolts UGH

Weld on new boxed in plates for the shock mounting stud.

[John Kat]

U bolts UGH

Weld on new boxed in plates for the shock mounting stud.

I wanted to avoid any welding...
By welding a lever to the boxed in plates and attaching it further along the frame, it should work?

[red1100]

I gotta ask: Why? Is it to much sag when you get on or a local styling thing? Suzuki has it pretty well dialed in and adjustable from the factory.

[John Kat]

I gotta ask: Why? Is it to much sag when you get on or a local styling thing? Suzuki has it pretty well dialed in and adjustable from the factory.

It's first of all to regain ground clearance since I fitted 17" wheels.
The front is now OK with Bandit 1200 stanchions in DL1000 Vstrom triples but the rear is too low by at least 30 mm.
The second goal is to make the bike more agile by reducing the trail.

[mmattockx]

It's first of all to regain ground clearance since I fitted 17" wheels.
The front is now OK with Bandit 1200 stanchions in DL1000 Vstrom triples but the rear is too low by at least 30 mm.
The second goal is to make the bike more agile by reducing the trail.

I can't say how it will work with the 17" wheels, but I put 1" longer shocks on my 82 1100E and that was enough to get it to the point of having occasional mild headshake in turns and it no longer tracks straight down the road without some minding. This is with stock wheels and Shinko 230 rubber. If my wife rides with me the bike goes back to tracking dead straight with no effort and cornering without twitches because her weight flattens off that extra inch of ride height. So be careful of how much you raise the rear, it doesn't take much to cause instability issues.

There is no way your rear ride height should be off by 30mm, a 130/90 Shinko 230 is 26.2" OD, a 160/60 is ~24.6" and a 180/55 is ~24.8". That translates to ~0.8" (20mm) at most of ride height change. Your front will be lower by more than that even with the Bandit forks because you lose so much more ride height at the front going to a 120/70 radial from the original 19" wheel.


Mark

[posplayr]

I can't say how it will work with the 17" wheels, but I put 1" longer shocks on my 82 1100E and that was enough to get it to the point of having occasional mild headshake in turns and it no longer tracks straight down the road without some minding. If my wife rides with me the bike goes back to tracking dead straight with no effort and cornering without twitches because her weight flattens off that extra inch of ride height. So be careful of how much you raise the rear, it doesn't take much to cause instability issues.


Mark

Raising the stock bike 1” is apples to oranges wher you start with suspension/wheel upgrades.
i had 18” wheels with radials 170 on rear and 1” and more was fine). I use Extendable ohlins $1500 + shocks. 35mm extensions

[John Kat]

[QUOTE=mmattockx;2507965]I can't say how it will work with the 17" wheels, but I put 1" longer shocks on my 82 1100E and that was enough to get it to the point of having occasional mild headshake in turns and it no longer tracks straight down the road without some minding. This is with stock wheels and Shinko 230 rubber. If my wife rides with me the bike goes back to tracking dead straight with no effort and cornering without twitches because her weight flattens off that extra inch of ride height. So be careful of how much you raise the rear, it doesn't take much to cause instability issues.

There is no way your rear ride height should be off by 30mm, a 130/90 Shinko 230 is 26.2" OD, a 160/60 is ~24.6" and a 180/55 is ~24.8". That translates to ~0.8" (20mm) at most of ride height change. Your front will be lower by more than that even with the Bandit forks because you lose so much more ride height at the front going to a 120/70 radial from the original 19" wheel.


Mark[/QUOTE
Modern bikes on 17" wheels run with a typical rake of 25° and 100 mm of trail ( CB 1000 R for instance)
I would expect that your problem comes from running non radial tires combined with the fact that your fork offset is much larger than the ones you find on modern bikes?
Currently my 1100 Katana with 330 mm shocks holds the rear wheel spindle at 385 mm from the center of the top shock support.
My GS 1000 framed bike with a monoshock increases that distance to 430 mm.
On top of that I'm running an 18" rear wheel and the handling is superb.
You might want to read Chuck78's thread on the subject?

[John Kat]

Raising the stock bike 1” is apples to oranges wher you start with suspension/wheel upgrades.
i had 18” wheels with radials 170 on rear and 1” and more was fine). I use Extendable ohlins $1500 + shocks. 35mm extensions

You are right but let's not forget that 1 inch higher or lower front or rear will change the caster by approximately 1° and that can be felt immediately.
I recently changed your rear 18" wheel for a 17" and the bike started to push the front wheel in the bends i.e. understeer.
There was only 20 mm height difference between the two...

[posplayr]

You are right but let's not forget that 1 inch higher or lower front or rear will change the caster by approximately 1° and that can be felt immediately.
I recently changed your rear 18" wheel for a 17" and the bike started to push the front wheel in the bends i.e. understeer.
There was only 20 mm height difference between the two...

I think my point is that there are many factors that would negate the 1" warning as some sort of upper limit on stability. In particular the fact that 1" is an accepted shock length extension well within stability margins of most reported customizations.
As I reported 35mm is about 1.3" of shock extension which equates to something in height (not sure what). I assume most people report shock length changes and equate those to rear height changes.

[mmattockx]

Raising the stock bike 1” is apples to oranges wher you start with suspension/wheel upgrades.

Yes, I understand that. 1" was not a magic number, the point was just that small changes can have large effects and to sneak up on it if at all possible.


Mark

[posplayr]

Yes, I understand that. 1" was not a magic number, the point was just that small changes can have large effects and to sneak up on it if at all possible.


Mark

That is one of the great fascinations of the motorcycle; how interrelated all of the dynamics are but still has two distinct modes of weave and wobble.

so yes small changes, and one at a time of possible.

[John Kat]

I did a quick computation of the trail generated through different triple offsets assuming a rake of 27°and a front wheel of 17"
Katana 1100 OEM 51.5 mm: 96 mm
GSXR 11K triple 35 mm: 113.7 mm
R6 2002 triple 40 mm: 108.1 mm
Vstrom DL1000 triple 45 mm: 102.5 mm
For comparaison and assuming the same rake of 27° the 1100 Katana with it's 19" front wheel would come out at 111.3 mm

[bwringer]

I don't think I've ever seen this done. And I agree that kit looks like a terrible, terrible idea.

The most usual thing people do is simply install longer shocks. Looks good, and you're not adding weight, modifying the frame, etc.

I guess I'm not clear on why you're determined to keep your current shocks. If they're the stock Suzuki shocks, they're decades-old crap anyway, and you'll love the benefits of modern shocks. Not cheap, I'll admit.

If they're decent aftermarket shocks, then the cheapest option would be to order up longer shocks and sell the old ones. Depending on what brand they are, sometimes you can order up longer bodies and swap in your springs.


I'm also wondering about fabricating some sort of little extender widget. An eye on one end that bolts to the frame like a shock, and the body rests against the frame so it doesn't rotate. The other end is sort of a clevis with a through bolt where you can insert the shock. I can envision this, but I've never seen anything like this. And of course you could envision a similar widget down at the swingarm, or a modification to the mounts on the swingarm.

Of course, these options are expensive as well, unless you just happen to have a complete machine shop on hand. In which case you wouldn't be asking this question in the first place...

[storm 64]

Here is the widget I came up with a few years ago... It mounts on the lower part of the shock absorber.