[Black_peter]

Knowing Md???
I'd have to guess sword!

[md86]

Yeah , the sword . But those land mines WOULD come in handy . Anybody know where I can get some ? E-bay maybe ?

[trinc]

UPDATE

I just got back from my bi-weekly brake practice..
I got the front to lock up. After doing a little "look around" the bike I noticed the front fork bottomed against the lower tree.. So this mod does NOT
reduce fork travel!

hey BP.

If you add more preload to the spring ( measured at .74 mm ) you MUST by the laws of physics reduce the travel of the fork. ( you may in some situations get the front tire to lock up BEFORE bottoming out - but if you start adding in hard braking - pot hole etc etc ? ))

although this sounds like a CHEAP mod - i would like to add this.

PVC - no way ! find a thin wall steel tube. but more important - the forks have a couple of setting to work properly - free sag, static sag & fork travel. by just adding preload to the soft stock spring i bet you will not be able to get it adjusted properly.

for $100 you can get a set of fork springs.

i had my forks rebuilt ( new preload spacer - springs - seals ) but also had the damping adjusted ( the amount of fluid that passes through the holes ) and the fork rebound adjuster reworked so that it actually works well ( with a noticable difference ).
it did cost me 3 1/2 bills ( GP suspension ) but the difference is amazing.
along with my ohlins rear shock ( contact cyberpoet ) the bike can really hold a line well on those spirited rides.

tim

[Black_peter]

UPDATE

I just got back from my bi-weekly brake practice..
I got the front to lock up. After doing a little "look around" the bike I noticed the front fork bottomed against the lower tree.. So this mod does NOT
reduce fork travel!

hey BP.

If you add more preload to the spring ( measured at .74 mm ) you MUST by the laws of physics reduce the travel of the fork. ( you may in some situations get the front tire to lock up BEFORE bottoming out - but if you start adding in hard braking - pot hole etc etc ? ))tim

Ahh not true..
Only if the spring itself limits the travel of the fork would adding a spacer change the travel.. I unfoutunatly have a small leak in my fork seal.
So after digging in with the front brakes I was able to see based on the
"high water mark" that the fork went clear to the lower triple tree..

I'm not sure what "physics" you are talking about...
only if the spring compresses 100% (a foolish design)
would adding 1" spacer reduce the travel 1"
(conservation of mass, is that what you meant?)
Look at your rear spring for a good idea of this..
You can see that compressing the spring 100%
would never be possible. There is XX inches of total compression
available in the spring XX - x in the piston of the shock.
So if you mounted the shock in a press and compressed it fully
there would still be gaps in the spring coil..

There is nothing scientific in this mod..
You could design the right spacer to effect the proper preload for you.
Or you could even build your own preload adjusters..
Or you could get GSXR forks..
But If you find your stock Kat springs are soft,
don't have the dosh for springs.. It does work..

[trinc]

i understand - but poor design if it bottoms out ? yes - but you are modifing the design.

adding preload will help / adjust the sag .
i wish i would have had the stock spring tested ( i may take it back when i bring them my ohlins for fine tuning ) but if it's a single rate spring doesn't that still leave you with a soft front end ? with a shorter stroke ?

i beleive they design the damping & oil weight & stroke so that the speed of the components won't allow the spring to compress all the way - but if you modifiy JUST the preload it seems like your asking for trouble.

tim

[Black_peter]

i understand - but poor design if it bottoms out ?

No poor design if the spring limits the travel..
yes - but you are modifing the design.

adding preload will help / adjust the sag .

true

but if it's a single rate spring doesn't that still leave you with a soft front end ?

Ummmm possible true..

with a shorter stroke ?

No! Longer because of the preload..

- but if you modifiy JUST the preload it seems like your asking for trouble.

tim

Trouble? I don't think so..
Not perfect to be sure.. but not trouble..
Otherwise preload adjustments would be a dealer only thing..

[trinc]

shorter stroke - i should have said that with the increase in preload the spring is compressed more so there is a decrease in the amount the spring can compress further.

right ?


tim

[Black_peter]

shorter stroke - i should have said that with the increase in preload the spring is compressed more so there is a decrease in the amount the spring can compress further.

right ?


tim

100% right...
But as my bike proves the spring still has room to compress..
Since I hit the external limit to the stroke..
The fork lower hitting the lower tree....

[trinc]

shorter stroke - i should have said that with the increase in preload the spring is compressed more so there is a decrease in the amount the spring can compress further.

right ?


tim

100% right...
But as my bike proves the spring still has room to compress..
Since I hit the external limit to the stroke..
The fork lower hitting the lower tree....

other than the preload - does the fork feel the same ?

i had mine done because:
i was sliding the front tire in corners ( riding hard )
& didn't like how the bike reacted to hard braking & hard acceleration


1 thing i don't know is that the spring rate is what keeps the tire planted to the road.

IF: you have a higher spring rate with less preload is that the same as a lighter spring with more preload ? seems if you plotted it, they would have a point were they're the same.

tim

[stevnmd]

Umm, I wouldn't be ONLY worried about bottoming out the fork, but now I'd think you run a serious risk of TOPPING out the fork, which is even worse. You're also raising the front ride height and thus altering the handling characteristics. You're also changing the rate of rebound.

[Black_peter]

Steve,
How are you changing the rate of rebound?
And yes you are raising the ride height but
the assumption is that the ride height is out of wack
to begin with..

I don't follow how this effects topping out the fork either.
This mod makes no changes to the over all stroke of
the shock. The only difference between this mod and
cranking on the preload of the rear is that it is
not adjustable.

I found:
The front tracks better (over road inconsistancies)
The dive is reduced.
Over all the handling is what I would call
"nutral"

[stevnmd]

Just make sure the fork doesn't top out, BP, that's the only thing I'd be concerned with if everything else "feels" better. Lord knows the stock suspension setup on the front of the Kat is as bad as they come, so I have no doubt it's an improvement...

You're changing effective rebound due to compressing the spring more. Single rate springs do in fact exert more force the further they compress. The rate of force increase is linear, that's all. The rate is constant, not the force exerted.

If you had a spring rated at 1.0kg/in, it would take 1kg of force to compress the spring 1 inch. 2kg for 2 inches, 3 for 3, and so on. Compress the spring 1 inch from the get go and it could now take 2 kg of force to compress it an inch further rather than only 1kg of force that it would have taken without the spacer. Hope that makes sense...

Anyway, if your fork was 2 inches from bottoming out prior to the spacer, it may have had only 3kg of effective rebounding force. However, with the spacer it could now have 4kg of rebound force which will quicken the rebound action. Add to that the fact that your bike is now resting without a rider closer to the top of fork travel and you've increased your chances of topping out the fork.

It could very well be, due to the weight of the Kat and its stock spring weight, that you WON'T actually top out the fork. It could also be that the Kat is so poorly damped to begin with that this helps tremendously. I'd just be cautious, that's all.

Adding preload can SOMEWHAT make it seem as though spring weight has been increased. It's half arsing it though. Bottom line... You want sag to be at 33% of total fork travel, meaning the distance between topped out and bottomed out. Forget 25mm, 30mm, or whatnot. Those just happen to be typical 33% measurements of sportbike fork travel distances. Get your static sag there and you're golden. Then you only need to worry about getting the damping right.

[ThAzKat]

I have my information from a very good source and he races on a regular bases. I have made the change and I also have the frontend lowered 20mm. I love the way it rides now and handles. If there were a issue with bottoming I would know, I weigh in at 220lbs and I am sure it would have a problem with the wheelie's and such.

[Anonymous]

Do what you gotta do . I mean c'mon , who HASN'T strapped some wierd sh!t to their bike before . I had a Claymore strapped to the side of mine once . I kinda enjoyed that . Maybe I'll do it again .... :-k

Why am I thinking this may be mild in comarison....?

[kwebbel]

Yeah , the sword . But those land mines WOULD come in handy . Anybody know where I can get some ? E-bay maybe ?