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2017 SXF 350 spring question

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Hi chaps,

 

I purchased a new spring for my bike from KTech who recommended a 54. I have 32mm static sag with 102mm rider sag but on fast bumps it feels like I'm riding a brick and the back kicks up. Also it isn't cornering so great.

 

I am 230lb without kit, c group rider.

 

Is this the right spring or could it be too much as looking on the mx-tech seems I should be on more like a 4.8

 

Thanks

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Not easy to answer ... 

Have you made the front stiffer via air to compensate (balance) the bike?

 

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Not easy to answer ... 
Have you made the front stiffer via air to compensate (balance) the bike?
 

This could well be the issue, I had been dropping the front pressure to a point where the forks are compressing to about 1.5" before the base - which is 135psi

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I'm 185 and running 148lbs, I'd think you'd be in the 155 zone

Ok thanks, I'll try increasing and see if it makes a difference

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7 minutes ago, guymx said:


This could well be the issue, I had been dropping the front pressure to a point where the forks are compressing to about 1.5" before the base - which is 135psi

Try setting the fork air pressure closer to what Steve 841 says, then adjusting the compression softer (turn adjuster "out") if that was what you were trying to accomplish (softer fork). With the stiffer "air spring" you might need to increase the rebound damping as well (turn adjuster "in" a couple clicks).

 

It's likely that because of your weight the forks are riding too low in the stroke and beat you up on chop which might make you think you need a softer setting. Going harder on the spring to hold it up in the stroke, then setting the compression a little softer might be just what you need.

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Try setting the fork air pressure closer to what Steve 841 says, then adjusting the compression softer (turn adjuster "out") if that was what you were trying to accomplish (softer fork). With the stiffer "air spring" you might need to increase the rebound damping as well (turn adjuster "in" a couple clicks).
 
It's likely that because of your weight the forks are riding too low in the stroke and beat you up on chop which might make you think you need a softer setting. Going harder on the spring to hold it up in the stroke, then setting the compression a little softer might be just what you need.

Ok great, I will give it a try. Thanks both for your help

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Is it the back that is stiff ? Your sags say that spring is good but you need more like 106mm sag , then adjust the compression high and low speed softer of it still feels rigid , try hs first

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102 and 32 is way to little. As Mog says 106/36 or so with 155-166psi in fork is needed. Dont go in to much on rebound in rear since it impacts frontend pressure. Let clicker sit at stock until balance is figured out.

 

I think you are at to stiff rear spring, 50nm maximum.

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Sags say he's not too stiff on spring

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No traction and superstiff is what that setup is with that kind of spring.

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His spring will give perfect sags as I said ?

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1 hour ago, mog said:

His spring will give perfect sags as I said ?

RT recommended a 5.2kg with his weight and ability... Again, maybe his shock is close but maybe he is feeling something different. He might be a rider who sits farther to the front, has his forks lowered quite a bit, or took an incorrect measurement... I think he's too soft with the 4.8kg...

Edit: I used the specs of a 16 350xcf...RT recommended a 5.4kg for his bike... 

Edited by Monk

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My chart says 5.0 but maybe his 5.4 is actually a 5.0

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Went out and tried 155psi and the bike was sooooo much better, it turns and feels perfectly balanced.
Shock felt good, I reset the sag again and have 32mm static sag and 104mm rider sag, but this is with only 5mm preload in on the spring (book says 9mm) so I think the spring is a bit too much for me

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I was at a 5.4 on my 2017 450 SXF. Went down to a 5.1 and I'm getting quite a bit of fender rub. I did free up my high speed compression and it made it substantially better. Going back to the 5.4 to get ride of the fender rub. I'm 220 in my birthday suit.

Also using 161 lbs up front and it cleared up the head shake issues.

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On 2017-06-04 at 5:46 PM, guymx said:

Went out and tried 155psi and the bike was sooooo much better, it turns and feels perfectly balanced.
Shock felt good, I reset the sag again and have 32mm static sag and 104mm rider sag, but this is with only 5mm preload in on the spring (book says 9mm) so I think the spring is a bit too much for me

Easen it up to 106 or so, and drop 1-3psi. Better traction. 4-5mm preload is good.

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