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Stigy

YZ 125 '08 KYB - am I geting full suspension travel ?

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Hi.

Lately I was checking my front suspension travel. The o-ring indicator stops more or less 1 inch from the bottom of the inner tube, even after flat landings and hitting harsh square bumps. Is it possible to make this suspension travel all the way down, so that the o-ring indicator goes full bottom ? I've tried fully back off the compression damping - can't get the suspension to work any further. Is it normal (1 inch from the bottom) or should i consider changing springs or valving ?

I weigh 165 pounds (with gear). Front springs are stock. Valving is changed by the suspension tuner for a guy 20 pounds heavier than me. Oil level is stock 0 (333ml).

Cheers.

Edited by Stigy

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They have probably 20mm more travel before fully bottoming.  If they work well though there's no reason to mess with them.  You don't have to use 100% of the travel.

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Sounds good to me also. I have been fighting the same issue but because I have 3 to 3.5 inches left. That is way too much IMO.

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All right. But what's the general rule here ? Should it compress fully, to zero o-ring bottom distance ? What can I do to use it fully ? As for now the only easy and quick option is lowering oil level. The compression clickers are fully or nearly fully out. The suspension feels a bit harsh. It doesn't mean that not using full travel is the reason, but i wan't to check it out. 

Edited by Stigy

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Clickers being almost fully out could be the reason for the harshness. If your forks travel too fast they hang in the lower part of the stroke making them feel stiff. Lowering fork oil or installing softer springs would be the ways to use more travel. Start by the oil, it's free and takes 10 minutes to do.

I have my forks setup so I have about 1/2 inch of travel left on a normal lap, but 1 inch is fine.

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Thanks guys.

I've been doing a light cross country race lately. The problem I got was the suspension being too stiff. No big jumps or bumps on the track so i didn't use last 1/3 of travel. Guys on KTM's, Beta's and Husky's were flying like on the flat table. My ride was harsh as hell. I've seen it on the videos I got. 3 bumps (Beta -80% susp. travel, KTM -80%, husky -80% my Yamaha - like 30-40%).

So I was thinking - do enduros and MX bikes (assuming it's the same bike) use the same spring rate/springs for particular rider ? Is the valving (and oil level) the only change you do when you tuning a suspension for enduro/CC ? Or should I go for softer spring ? As I understand it - the spring and preload are selected for a rider, not a type of riding you want to do. Am I correct ?

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38 minutes ago, Stigy said:

As I understand it - the spring and preload are selected for a rider, not a type of riding you want to do. Am I correct ?

Type of riding can also determine spring rate, as an example,

taking say the 2004-07 era Honda CRF250R (motocross) and CRF250X (offroad) bikes.

The CRF250X weighs at least 30lbs more yet has softer fork and shock springs.

 

Typical fork & shock spring rates and, weight of bikes:
 

CRF250R    .45kg/mm -  5.3kg/mm -   223lbs.

CRF250X     .42kg/mm -  4.8kg/mm -  253lbs.

Edited by mlatour

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All right. But change of spring rate affects the sag, didin't it ? So we talk about not only different spring rates but also the other sag parameters. Or am I missing something ?

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On 11/7/2018 at 10:22 PM, Stigy said:

Valving is changed by the suspension tuner for a guy 20 pounds heavier than me.

additional to weight, valving is tuned to match the rider's skill level,

a faster rider requires stiffer settings.

 

This IMO would be more of an issue than spring rates versus usage.

Edited by mlatour

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7 minutes ago, Stigy said:

All right. But change of spring rate affects the sag, didin't it ?

At 165lbs, the stock YZ125 spring rates (.42 - 4.7) are correct for you.

I'm 160lbs, by memory at 95-100mm of race sag, you should obtain around 30mm +/- 5mm of static sag.

 

Edited by mlatour

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5 minutes ago, mlatour said:

additional to weight, valving is tuned to match the rider's skill level, 

a faster rider requires stiffer settings.

That's the important aspect mlatour. Thanks.
But i've gone a little bit off topic here. I ask about mx to enduro/cc conversion. I wanted to know if you tune the same bike with the same suspension, converting it from mx to enduro/cc/woods should you consider changing spring rates then.

Edited by Stigy

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1 hour ago, Stigy said:

I've been doing a light cross country race lately. The problem I got was the suspension being too stiff. No big jumps or bumps on the track so i didn't use last 1/3 of travel. Guys on KTM's, Beta's and Husky's were flying like on the flat table. My ride was harsh as hell. I've seen it on the videos I got. 3 bumps (Beta -80% susp. travel, KTM -80%, husky -80% my Yamaha - like 30-40%).

Just a thought but just maybe those enduro bikes were setup too soft for jumps, reason they use up more travel.

Your harsh ride being that it was revalved for a 20lbs heavier rider? (with unknown skill level and usage)

 

I've stopped trying to 'get more travel' from my CRF250X forks,  (no kidding, I'm up to 20 revalves in 3 years)

all experiments to soften damping, lower the oil volume, soften the springs etc. just made the bike handle worse and worse.

I now go by 'what feels the best' even if it only uses up 2/3rd of the stroke, it also leaves a safety margin for unexpected hits.

On closed cartridge forks, I think most of the gains are found by tuning the midvalve.

Edited by mlatour

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29 minutes ago, mlatour said:

Just a thought but just maybe those enduro bikes were setup too soft for jumps, reason they use up more travel.

Of course they were set too soft for big jumps. Enduros arent suppose to hit big jumps and land without bottoming. The problem was - there were no big jumps or square bumps on the track. That's why my stiff suspension was worse on this track.

 

29 minutes ago, mlatour said:

Your harsh ride being that it was revalved for a 20lbs heavier rider?

The tuner who did this said that 20lbs doesn't make much difference. Especially for non professional rider. The PO was quite good - better than me for sure. The suspension was set for mid-soft mx tracks.

Edited by Stigy

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2 hours ago, Stigy said:

Thanks guys.

I've been doing a light cross country race lately. The problem I got was the suspension being too stiff. No big jumps or bumps on the track so i didn't use last 1/3 of travel. Guys on KTM's, Beta's and Husky's were flying like on the flat table. My ride was harsh as hell. I've seen it on the videos I got. 3 bumps (Beta -80% susp. travel, KTM -80%, husky -80% my Yamaha - like 30-40%).

So I was thinking - do enduros and MX bikes (assuming it's the same bike) use the same spring rate/springs for particular rider ? Is the valving (and oil level) the only change you do when you tuning a suspension for enduro/CC ? Or should I go for softer spring ? As I understand it - the spring and preload are selected for a rider, not a type of riding you want to do. Am I correct ?

You would need to increase the float on the mid valve to get your fork working more like the enduro bikes.  Pulling one face shim will help tremendously as it increases the float and softens the stack. 

I wouldn't mess with oil level.  Your issue is MX valving.

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Maybe I should return to stock valving and see how it feels... Could be time consuming thought, because i should revlave rear shock too if i mess with forks.
Another option is go back to susp. tuner to see what he can do...

Modifying it myself ? hm.. i know all i need to know to do it. But I lack of theory on shim stacks. I might screw up more than upgrade. +I think I should mess with the shock too if I revalve the forks - and don't know anything about shock to forks changes reference when it comes to valving...

Any advices from You guys ?
What should I do if i want this suspension still usable on MX tracks but adapt it a little bit for CC races ?

 

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The shock doesn't have to be revalved if it's feeling good

You need to soften valving for woods etc compared to Mx

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Shock feels perfect. The only thing is, the rebound damping is huge. I often ride RD full out, it's good at this setting. You think it's worth it to try and do it myself ? Any literature where i can find some essential hints ?

 

Edited by Stigy

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There are lots of utube videos to help you service forks and shocks ,less so to show revalving

If your shock has the adjuster fully open on rebound ,your stack is way too stiff , and you have a high bleed shock ,where alot of damping is being bypassed by going past the rebound adjuster ( it bleeds both ways on compression and rebound ) so you will change the feel of the shock by changing the shim stack and the rebound adjuster position

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