Do I need stiffer springs?

[wronskain]

So recently bought a mint 2001 KX125 that I bottom what seems like all over the place. I have a feeling that I need stiffer springs. What will happen if I really crank on the compression damping adjustment to compensate for this? Right now the settings are stock (clickers and all) and it kicks side to side horribly down choppy straights.

I'm 185lbs, and I ride strictly motocross. I do most of my riding at Hangtown which has some decent sized jumps. I have no idea what class I'd race in now, but back in the the day I was a slow 125 Intermediate/ fast 125 Junior. I took about a 10 year break of no riding so I'm considerably slower now, but getting my speed back slooowwwlly. Advice? Should I mess with the stock stuff or should I not bother and send it off for revalving?

As you can see in this picture, I'm pretty big on the bike!

http://www.theshagpad.com/hangtown1/images/img_5849.jpg

[kawamaha]

I would recommend 0.44 fork springs but you can go there:

http://www.race-tech.com/

there must be a spring calculator

[killerdwarf77]

If you knew how to set up your suspension properly, you would get your answer from your amount of free sag. I am not trying to be an ahole, but by looking at your picture, you do not really know how to set up your bike properly, your handlebars are set to low, they should be set up so your hands are in line with your suspension!. If you do not have a factory manual for your bike, get one, read it, take it to the track and learn what all those screws and nuts on your suspension do to the hadeling of your bike! Also take a look at the suspension linkage, make sure evey joint is moving properly, and smoothly.

[DaveJ]

killerdwarf77 is right - you don't base a spring selection based on bottoming, you base it on sag or ride height. It can get a little more technical than that, but for now, start with this.

Expect rear numbers within the 90 to 110 range, and the front at about 30% of total travel.

If you're close to that, consider changing one of the many other things that can help with how fast the suspension is moving through the stroke and how hard it's going to arrive once it gets there. Oil levels, nitrogen charges and various end-of-stroke hydraulic systems are often the key to lesson or soften bottoming problems. And of course, compression damping can play a key role in the velocity of the suspension.

Let us know if you need more detail than that.

[HappyG]

I would recommend 0.44 fork springs but you can go there:

http://www.race-tech.com/

there must be a spring calculator

according to the race-tech site they recommend a

.425 fork spring (.410 is stock),

and a 5.0 shock spring (4.8).

that would be a good place to start.

[onecolumbyte]

As I understand it kicking side-to-side during chop is a sign of packing. Try softening the rebound a little.

Best way to tune suspension is to make 1 adjustment at a time, see if you like it, and keep immaculate records. Find the spot on the track where it kicks, adjust the clicker one way or 't other, and run it again. Just like they do it at the optomatrist "better or worse?"

[berudd]

Well, I won't try to assess your ability or intellegince from looking at a picture but when was the last time the suspension was serviced. The oil in there has a lifespan and when it is done, it can cause the suspension to perform poorly.

That said, I do think you need heavier springs. And while you can do good things with stock suspension, a revalve by someone that know what they are doing will always be better.