DRZ-400 Suspension Help


6 replies to this topic
  • captd1

Posted August 30, 2005 - 02:39 PM

#1

I have been riding this bike for about a year off road, and am finally getting around to tuning the suspension a bit more (within factory limits). I have read the articles on setting sag and preload, but would appreciate any good input. When riding the whoops (sandy in FL), my rear shock flexes alot, and it feels like I ride each one. Recently I rode my friends stock 350 KTM, I was AMAZED, I flew almost flat over the tops of the whoops! Since then I have cranked my rear spring down, added some compression up front (same damping), and increased the damping a bit in the rear. I did dial up the damping too high in the rear, and the back end hopped and almost came around front. I know it's alot of trial and error, but since I've seen my friends bike do it, hopefully I can dial in mine. Thanks for any constructive input. Sorry I'm a little long winded. :D

  • McGyver

Posted September 01, 2005 - 12:48 AM

#2

This website could be useful for you. Reply here for questions and other. Bye!

http://www.gialma.it...rz_suspensions/

  • captd1

Posted September 01, 2005 - 04:26 AM

#3

Thanks for the response. I have seen that site, and I realize my questions are a bit open. I'll test my adjustments soon, and hope for a real improvement.

  • fishnbc

Posted September 01, 2005 - 07:30 AM

#4

Nice write up on revalving the forks McGyver :D

  • McGyver

Posted September 01, 2005 - 10:07 AM

#5

Nice write up on revalving the forks McGyver :D


Thank you!




Thanks for the response. I have seen that site, and I realize my questions are a bit open. I'll test my adjustments soon, and hope for a real improvement.


>I rode my friends stock 350 KTM, I was AMAZED,
>I flew almost flat over the tops of the whoops!

This can happen with the drz, too, when the suspension are well tuned.

>....Since then I have cranked my rear spring down,
>added some compression up front (same damping),
>and increased the damping a bit in the rear. I did dial up
> the damping too high in the rear, and the back end hopped
>and almost came around front. I know it's alot of trial and error,
>but since I've seen my friends bike do it, hopefully I can dial in mine.
>Thanks for any constructive input. Sorry I'm a little long winded.

You can try and try and try, but it's impossible to improve the stock drz suspensions turning screws and changing preloads only. What's written in that website is the minimum actions you can do to obtain a decent bike, probably better than your friend's Ktm. You must absolutely change the springs (at least, the shock spring), and it's very important that they will be in a perfect stiffness' ratio.
You can choose springs for a rider's weight bigger than yours, if your style is very aggressive, with long jumps and so on.
It' very important to change the hydraulic fork setting, too. You can postpone only the shock revalving: you will lose a bit performance, but not very much. Remember to turn the compression damping screws (they're coaxial) completely in, in this case.

  • captd1

Posted September 01, 2005 - 10:59 AM

#6

You must absolutely change the springs (at least, the shock spring), and it's very important that they will be in a perfect stiffness' ratio.

It' very important to change the hydraulic fork setting, too. You can postpone only the shock revalving: you will lose a bit performance, but not very much. Remember to turn the compression damping screws (they're coaxial) completely in, in this case.


Thank you for the info. I'm not quite ready to send my whole suspension out for rebuild, just whatever 'tuning' I can do myself. The DRZ S and E have the same suspension, right?? I imagine the KTM just had stiffer springs, but it was stock. You're recommending stiffer springs both back and front? But I should start by cranking up the compression ALL the way in the front fork? I did crank it up a bit, but I think I had the front damping too high also, slowing the travel. I am a fairly aggressive Intermediate rider, but not racing, only 180 lbs with gear. I have never bottomed out the suspension, but I'm sure the rear got close. I'm not sure I want to tear down the fork. I could probably install a kit, but not qualified to adjust every shim. Thanks again.

  • McGyver

Posted September 01, 2005 - 02:01 PM

#7

Fork--------shock-------rider's weight (kg)
3.8----------53----------------65
4.0----------56----------------75
4.2----------59----------------85
4.4---------61-62-------------95
4.6---------64-65------------105
4.8----------67---------------115


Your weight is 180/2.2 = 82 kg. In the above table (the same that's in my website)
you can see that the right springs for you should be 4.2 N/mm (or 0.42 kg/mm) fork and 59 N/mm (or 5.9 kg/mm) shock. A stiffer choice could be 4.4 (stock fork springs) and 61 or 62 for the shock. Many people mount the 60 N/mm spring with stock fork springs, too.


> Thank you for the info. I'm not quite ready to send my
>whole suspension out for rebuild, just whatever 'tuning' I can do myself.

OK.

>The DRZ S and E have the same suspension, right??

Now, yes. Some years ago, no. You have the E or the S?

> I imagine the KTM just had stiffer springs, but it was stock.

NO! Ktm suspensions are more equilibrated than drz's. They could be a little stiffer, too, but it's not so important! Most people think:
- More stiffness, more performance! -
It's false. Equilibrium is the keystone of suspension.

>You're recommending stiffer springs both back and front?

Not exactly, look at the table.

>But I should start by cranking up the compression ALL the way in the front fork?

I hope you're speaking of the "E" fork, mounted on the more recent "S", with compression adjuster on base valve and extension adjuster on top. If this is the case, you should start turning completely out (=softening) the compression adjuster, then tuning the rebound adjuster in order to have the same behaviour of rear.

>I did crank it up a bit, but I think I had the front damping
>too high also, slowing the travel.

Only the revalving can improve the fork very much, if well done.

>I am a fairly aggressive Intermediate rider, but not racing, only 180 lbs with gear.
> I have never bottomed out the suspension, but I'm sure the rear got close.
>I'm not sure I want to tear down the fork. I could probably install a kit,
>but not qualified to adjust every shim. Thanks again.

Then, 4.2 - 59 should be your perfect springs. Bye!





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