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BGoyins

2015 YZ450 Suspension advice

30 posts in this topic

I'm trying to see if I can get the stock suspension to work well without getting new springs and/or a revalve.  I weigh 170lbs without gear, motocross primarily, and maybe a "B" rider on a good day. My current settings are: race sag : 105-110mm, static sag 46mm,  HSC 1&3/4 turn, LSC 12 clicks, rebound 9 clicks; Forks 3mm above triple clamp, compression 16 clicks, rebound 8 clicks. It still feels a bit stiff. I'm turning the compression out to soften up the ride, but I have to put more rebound in or it bounces like a pogo stick. Is this what starts to happen if a spring is too stiff, or is this normal? Thanks in advance.

 

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Maybe. I believe stock rear spring is a 5.9 and at your weight a 5.83 is recommended but the next one down is a 5.7kg.

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Maybe. I believe stock rear spring is a 5.9 and at your weight a 5.83 is recommended but the next one down is a 5.7kg.

Stock springs are 5.9/.51kg/mm.

A 5.7 rear and .49 fork springs should get it working much better but you will run in to packing problems with the forks until the rebound valving is redone for the springs.

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I wouldn't go lighter. I am 165 without gear. I went lighter one weight on the front for woods and I often feel like it's to soft on the track. Anything other than a perfect landing and I bottom fairly hard. I'm running the clickers within a couple clicks of stock. Also my suspension was very stiff for the first 10-15 hours. Maybe give it a little more ttime if your not there yet

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Stock springs are 5.9/.51kg/mm.

A 5.7 rear and .49 fork springs should get it working much better but you will run in to packing problems with the forks until the rebound valving is redone for the springs.

Thanks for the input. These are the spring rates I'm considering if I make a change. Is the rebound unable to be set light enough with a lighter spring?

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I wouldn't go lighter. I am 165 without gear. I went lighter one weight on the front for woods and I often feel like it's to soft on the track. Anything other than a perfect landing and I bottom fairly hard. I'm running the clickers within a couple clicks of stock. Also my suspension was very stiff for the first 10-15 hours. Maybe give it a little more ttime if your not there yet

Thanks for the advice. You're right, I should give the suspension a chance to break-in. I only have about 3 hours on it. Also, did you go down to a .49 fork spring? I think it's interesting that the 14 had a .50 spring and the 15 uses a .51 spring with less oil in the fork. Makes you wonder if you can really feel a .01 difference??

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Thanks for the advice. You're right, I should give the suspension a chance to break-in. I only have about 3 hours on it. Also, did you go down to a .49 fork spring? I think it's interesting that the 14 had a .50 spring and the 15 uses a .51 spring with less oil in the fork. Makes you wonder if you can really feel a .01 difference??

The 2014 has .49 fork springs from the factory. I swapped Mine for a set of .47 out of a 2014 yz250f. Your .01 is entirely relative to the unit of measurement being used. In the case of suspension and all the forces in play, .01 does make a difference. The Thing is that only the top pros would actually feel it. That doesn't mean that it won't have an effect for you, you just won't notice it in real time.

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The 2014 has .49 fork springs from the factory. I swapped Mine for a set of .47 out of a 2014 yz250f. Your .01 is entirely relative to the unit of measurement being used. In the case of suspension and all the forces in play, .01 does make a difference. The Thing is that only the top pros would actually feel it. That doesn't mean that it won't have an effect for you, you just won't notice it in real time.

The 2014 has .50kg fork springs stock.

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The 2014 has .50kg fork springs stock.

You are correct. For some reason I always mix up kg and N/mm. They are 4.90 N/mm. In either form, I dropped to the next lower spring and In my opinion it is to soft on a track for my 165 + gear.

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I bought 2014 250f springs to install on my 2014 450f. I am hopping to install them this week and try them out this weekend. I am 160lbs C class rider so I am hopping they are soft enough. I will let you know how I like them.

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You are correct. For some reason I always mix up kg and N/mm. They are 4.90 N/mm. In either form, I dropped to the next lower spring and In my opinion it is to soft on a track for my 165 + gear.

You should check with JS264 on here I think he weighs about the same. I would think a .48 front would be about right

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Setting the rear shock rebound "light enough" is not usually a problem with most YZ's.  Getting it stiff enough without having it "pack up" in closely spaced whoops is a more normal issue.  Kind of a YZ tradition, for some reason; the shock lacks initial rebound, while the fork has a little too much.

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I bought 2014 250f springs to install on my 2014 450f. I am hopping to install them this week and try them out this weekend. I am 160lbs C class rider so I am hopping they are soft enough. I will let you know how I like them.

Please do. Thanks

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Setting the rear shock rebound "light enough" is not usually a problem with most YZ's.  Getting it stiff enough without having it "pack up" in closely spaced whoops is a more normal issue.  Kind of a YZ tradition, for some reason; the shock lacks initial rebound, while the fork has a little too much.

Thanks Gray, JS264 said" A 5.7 rear and .49 fork springs should get it working much better but you will run in to packing problems with the forks until the rebound valving is redone for the springs." I was curious why the forks would start packing if going to a lighter spring? Wouldn't a lighter spring require less rebound? As usual, your explanations are welcomed.

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Thanks Gray, JS264 said" A 5.7 rear and .49 fork springs should get it working much better but you will run in to packing problems with the forks until the rebound valving is redone for the springs." I was curious why the forks would start packing if going to a lighter spring? Wouldn't a lighter spring require less rebound? As usual, your explanations are welcomed.

Lighter springs require lighter(less) rebound damping as you say. The forks will pack because the lighter springs will not have enough force to push past the heavier valving for the heavier springs. Packing will cause harshness, headshake, and will disturb handling characteristics.

You can run a rate down from factory without changing anything but you'll have to run the rebound clicker way out (like 17-18 clicks) which increases midvalve bleed and can have some negative side effects such as pushing in corners while still having it pack on large successive hits.

The stack before the stock crossover is alright but the high-speed portion of the stack needs lightened with lighter springs.

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So then my question to Gray and js264 is this. Is it better to leave the stock springs in and be a little over sprung if you can't afford to revalve? Or can you benefit from the softer springs without re valving? It sounds like going lighter on the springs May cause more issues than anything without valving to go along with them. Could this be why I feel like my forks are harsh on the little stuff but bottom relatively easy with the .49 springs? I mean rt suggests .453 for my weight and skill. I couldn't imagine being that soft.

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"In general", if you have to err one way or other, too much spring is better than too little.  Obviously, you can go way overboard with that and have springs that that are genuinely too stiff to be workable, but it's also true that a step too light is apt to give ride qualities that are more objectionable than a step too heavy will do. 

 

To compensate for a too light spring, the compression damping has to be cranked up higher than normal, and you can end up with an overall harshness that you don't get from simply having a little too much spring support.  At normal, flat ground ride heights, you'll also sit deeper into the stroke with a lighter spring, which will shorten the travel available to the compression stroke and thereby reduce its ability to absorb energy, again contributing to a harsher ride.

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Why not just try 10cc less oil in the outer chamber? I too think the '15 is a little stiff compared to my 2011 and 2012 models. I weigh 175, but only have 12 hours on the bike. I have yet to bottom the forks, and have ridden some tracks and riding areas where they should have been to the stops. Just drained the oil over the weekend and will try it this Saturday. I hope to gain a little more compliance, and if harsh bottoming will fix with the comp clickers. I have a feeling this should do the trick.

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