instead of installing progressive springs...can I just put in the thickest fork oil there is?  

instead of changing shocks...can i preload them to the tightest?

oh yea you can. dont know if it would work but im 99% sure you can do it.

If you run the preload up to max then you will be limiting the amount of travel available.

so what is the best way to set the shock suspension?

and how much better are denser fork oil?

spring rate controls fork travel.
preload controls sag (where the fork settles at "rest").
oil viscosity controls damping (on a dumb damping rod fork anyway).

Changing to a thicker oil (from 5 to 10~15 wt) will help to a certain extent. It will keep the bike from diving and bouncing as much as it does stock.
BUT just filling the tubes with mollassis is not only a bad idea, it could be dangerous because the forks will be very harsh over bumps and could "pack in" and really upset the bike.

The proper springs keep the forks from bottoming out, but aren't overly stiff that the suspension can't move it full range.
The stock springs are wimpy, but they can be used for mild street rideing just by changing the oil to *slightly* heavier wt.


On the back, you can't change the oil or anything but the preload. Again tightening it up all the way will make the bike very harsh over bumps and you can get chatter in turns as the back tire literally skips over the road.

ok...thanks JamesG
so basically you're saying that to get the performance I want...the best way is still to change the springs and shocks...
guess there's no cheap way out of this

Thanks everyone for their input...

Put 20wt fork oil in the front and set the shock spring preload to the max setting. I'm assuming we're dealing with stock suspension parts.
There will be some improvement. But if it's not as much as you would like, then you need new springs up front and a different shock.
I put 20wt in my stock 89 front forks, and it really helped.
I've had it on the track as well as seriously heinous street riding :mrgreen:
I do have a Fox shock on the rear though.

what's the max density fork oil can i put into stock forks?

I don't think fork oil comes any heavier than 20wt.
even that may be hard to find. If you can't find any 20wt, just go 15wt minimum. I wouldn't try any other type of oil.

You can easily find 20 wt fork oil at any shop that caters to dirt bikes.

if i put fork oil that is too dense...will the stock forks not support it?...for example...will it be too much pressure and cause leaks?

be glad you don't own a real sport bike that has a good suspension.....

with all the GURU's and stealers pushing/selling $1100-1300 penske shocks
and $500-600 fork work from that ass packer "max"....

all of a sudden....100 buck fork springs/fork rebuild and a 100 buck GSXR shock are a friggin' bargain

Putting 20wt in the GS forks is fine. Just make sure to put the correct amount in. Overfilling will cause more problems than heavier oil.
In fact the 20wt slowed the leak on my seals.
I'm going to rebuild my 89 forks with .85 Race Tech springs and emulators.
You can find GSXR shocks pretty cheap on ebay. (89-95 shock)

Progressive springs were worth every penny.  I got them at a local shop for $100 CAN.  They were actually cheaper at the shop than over the internet.  The bike's handling was improved dramatically.  Much firmer around corners and no more bottoming out while braking (dangerous).  I did not use a heavier fork oil.

About pre-load.  There may be some confusion but there is no way to change the preload on the front springs other than putting in a spacer.  I wouldn't recommend it as is limits the travel.  It may increase the initial stiffness but will not stop the bottoming out.  

Rob