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Should I adjust the 2018 yz450f forks?

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Hey guys, just has my first ride on a brand new 2018 YZ450F. First off, I love the bike as I am coming from a KX250 two stroke. However, I am noticing that in whoops or tight areas in the desert that the suspension seems a little stiff- like I am fighting the handle bars on every bump. Is it worth it to adjust anything with the forks (or rear shock)? Or should I break it in more before making any changes?

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I just had this argument with a buddy that picked up his new 2018 YZ last week.  He didn't like how his bike was handling on the first day out but he insisted that he wanted to ride the bike and break in the suspension before adjusting it.  I told him he was nuts and should have made the changes I recommended from my one years experience on the bike before he ever started it up.  After the argument I did convince him to at least check the shock sag.  It was 130mm because he weights 230.  I have no doubt his bike handled like crap.  He will probably need stiffer springs.

At least set the sag before riding.  It effects every part of how that bike handles.  You may have to adjust it again when it is broke in but it is worth the extra effort.  I also would start with the forks set to what Motocross Action recommended. 

KT

 

 

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Setting sag and fork level is beneficial at all times and should be adjusted right from the start. The valving will take a set in the first 5-10 hours of riding though, and feel noticeably softer after that. 

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51 minutes ago, MXKyle said:

I just had this argument with a buddy that picked up his new 2018 YZ last week.  He didn't like how his bike was handling on the first day out but he insisted that he wanted to ride the bike and break in the suspension before adjusting it.  I told him he was nuts and should have made the changes I recommended from my one years experience on the bike before he ever started it up.  After the argument I did convince him to at least check the shock sag.  It was 130mm because he weights 230.  I have no doubt his bike handled like crap.  He will probably need stiffer springs.

At least set the sag before riding.  It effects every part of how that bike handles.  You may have to adjust it again when it is broke in but it is worth the extra effort.  I also would start with the forks set to what Motocross Action recommended. 

KT

 

 

Interesting. I am really into weightlifting and lifting heavy, and weigh around 220. Maybe what he’s feeling is similar to me.

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4 hours ago, mikespimpin said:

Interesting. I am really into weightlifting and lifting heavy, and weigh around 220. Maybe what he’s feeling is similar to me.

My 160# kid (16 yo Pro mx rider) runs stock springs and the suspension works good for him. I would think they would be to soft for you 

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8 minutes ago, gedakbx said:

My 160# kid (16 yo Pro mx rider) runs stock springs and the suspension works good for him. I would think they would be to soft for you 

Ok thanks for the data point. Current plan is to check (and possibly adjust) the sag and take it for a few more rides.

EDIT: maybe I just don't know the difference between soft/stiff forks? It sure as hell doesn't feel like im sitting on a sponge when I hit some whoops, have to really hold on and fight the handlebars

Edited by mikespimpin

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Even undersprung, the bike will feel stiff as you are riding in the lower portion of the stroke

rather than the suspension being properly held up to absorb smaller bumps.

 

Quite often, stiffer springs provide a plusher feel, the suspension staying up in the stroke,

what is know as 'mid-stroke harshness' is perhaps what you are currently experiencing.

 

In stock form, most full-sized bikes are set up for a 180lbs or so rider  (apart perhaps for 125's)

and as a rules of thumb, for each extra 15lbs in weight, one step stiffer springs are required.

 

Going 2 or more rates stiffer on springs usually requires some internal rebound valving changes to control the increased stored energy of stiffer springs.

Edited by mlatour
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49 minutes ago, mlatour said:

Even undersprung, the bike will feel stiff as you are riding in the lower portion of the stroke

rather than the suspension being properly held up to absorb smaller bumps.

 

Quite often, stiffer springs provide a plusher feel, the suspension staying up in the stroke,

what is know as 'mid-stroke harshness' is perhaps what you are currently experiencing.

 

In stock form, most full-sized bikes are set up for a 180lbs or so rider  (apart perhaps for 125's)

and as a rules of thumb, for each extra 15lbs in weight, one step stiffer springs are required.

 

Going 2 rates stiffer on springs usually requires some internal rebound valving changes to control the increased stored energy of stiffer springs.

Thanks a lot! Very informative. Looks like I need to adjust the stiffness of the rear spring. Also, I didn’t quite understand your last part... I feel like I should go 2 or 3 steps stiffer on the spring. Are you saying that I will need to have more than just the spring adjusted? I don’t have the manual close by right now, or I would look it up. I assumed it would just be some kind of easy adjustment, but maybe not...

Edited by mikespimpin

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You'll need to stiffen both ends, meaning the fork and shock springs.

Yes if the spring rate increase is drastic, it will very likely require internal changes (valving) to both ends.

 

As many suggested, start by setting your race sag to the recommended height,

the residual static sag measurement may give an indication of how far off the rate is for you.

 

New components do take some time to break in but it's quite evident that at 220lbs a stock bike will be undersprung for you.

Edited by mlatour

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4 minutes ago, mlatour said:

You'll need to stiffen both ends, meaning the fork and shock springs.

Yes if the spring rate increase is drastic, it will very likely require internal changes (valving) to both ends.

 

As many suggested, start by setting your race sag to the recommended height,

the residual static sag measurement may give an indication of how far off the rate is for you.

 

New components do take some time to break in but it's quite evident that at 220lbs a stock bike will be undersprung for you.

OK thanks again. FYI, according to the Racetech calculator, it says I should have 0.5kg/mm for the fork springs (stock is 0.51kg/mm), but for rear it says:

 

REAR SHOCK SPRINGS

Recommended Spring Rate:6.3 kg/mm (Use closest available)

Stock Spring Rate:5.7 kg/mm (stock)

 

Possible I only need to adjust the rear shock?

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Possible but many have commented that the Race Tech calculator often suggests too soft fork springs,

perhaps spring rates suited to best work with their own 'internals' (Gold Valves)

 

Start by setting the sag and, allowing some time for components to break in a bit.

Perhaps going a bit stiffer on the compression clickers until everything is figured out.

Edited by mlatour
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You can try the stiffer shock spring with the stock fork.  That is the set up I run and am 235.  Although I am tall so I lever the shock more than the fork.  I also have mine valved for my riding style and sit whenever I can due to a bad knee.  Point is many different ways to do it.  Just do one thing at a time and remember clicker adjustments and oil levels relatively free.

 

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Hey guys, according to this website: https://rideexpeditions.com/off-road-suspension-getting-the-perfect-set-up/

Quote

 

PROBLEM

Suspension feels too hard, ride is harsh and travel not being used

SOLUTION

Rear – reduce compression damping, reduce spring preload or change spring /spring rate.

Front – reduce compression damping and change springs / spring rate.

 

Is it not worth it to try and make these adjustments on the stock spring / forks before I go out and buy a stiffer spring? Maybe I am misunderstanding, but is this telling me to soften up the suspension?

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You will never get the suspension to work properly for you until you have the correct springs for your weight. That needs to be your first step.

Like others have already mentioned, if your springs are too soft for your weight, just sitting on the bike you are already using up the plush part of your suspension before even riding.

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