FIX for HSC damping (forks)

Bikedude987

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First I'll preface saying that I don't want to take any business away from Nick of Stoltec Moto and highly recommend him if you are at all uncomfortable doing your own work. This modification will not get you to the same level as his work. but it is a significant improvement over stock, especially when paired with his linear fork springs. BUT, if you're DIY and capable, there is an easy way to vastly improve your forks with all stock valving components.
I posted this in a thread in Technical, but figured it should have it's own thread.



IF you're comfortable doing your forks and are willing to take apart the damper cartridge, Yamaha has left us all a nice easter egg in there.

Once you've got the compression piston out of the bottom of the damper cartridge, you'll see that the three compression ports are only about .025" holes. You can open these up (with a hand drill if careful, I didn't want to indicate them in on the mill...) to around .0625, maybe a little bigger. Even with the stock shim stack this makes a monumental difference.

FYI, when I did mine I also put in .80 springs from Nick and 5w oil, forget the brand...

Pictures are of the components in order, the stock piston, then the modified piston.




 

Koinz

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I already have the Penske valving so I won't be doing this, but I was just wondering on what improvement you experienced over the stock sized holes.
 

Checkswrecks

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How much do you weigh?
What type of riding do you do?
 

avc8130

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This is a common mod on dirt bikes.

This is basically allowing more oil through to act on the shim stack. This essentially "loosens" up the high speed compression.

Bikedude,

Have you tried modifying the shim stack at all?

ac
 

Checkswrecks

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I'm aware, but how much also depends on the questions I asked.
 

Bikedude987

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I had to do some other things to the forks (ass custom spring caps so they don't rattle, replace leaky and uncleanable stock seals) so I redid the HSC shim stack.

I've got it written down at home, but I think I remeber it.

Stock:
16x.1 (3)
11x.1 crossover
16x.1
14x.1
12x.1
10x.1
9x.1
16x1.5 (washer)

What I changed it to was:
16x.1 (3)
10x.1 crossover
15x.1
13x.1
11x.1 (supposed to be an 11, but it didn't show up with the order, so I made due)
9x.3
16x1.5

It is awesome! The front end soaks up rocks and washouts like they aren't there and is stable and predictable in the corners. Some fine tuning with the clickers and I'll be in the money.
Oil height is 140mm, btw and gives excellent bottoming resistance. I probably could have gone with 145mm, but time will tell.
 

avc8130

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Looks great! Thanks for sharing the info so others can try!

What do you weigh?

Are you watching suspension travel with a zip tie/o-ring on the fork slider?

ac
 

yz454

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You did a good job taking the initial hit out and good progression . I am going to start my yz fork conversion soon.
 

spam16v

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That's the stuff I was after. Hard to get someone to share their stack sometimes. Thank you.
 

Bikedude987

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I checked my literature and changed some numbers in the shim stacks posted above. The numbers there are now correct for both stock and modified.
 

avc8130

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Bikedude987 said:
I checked my literature and changed some numbers in the shim stacks posted above. The numbers there are now correct for both stock and modified.
What do you weigh?

ac
 

avc8130

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Bikedude987 said:
I weigh ~185 with gear. I regularly ride with a passenger of about 175 and maybe 50lbs of gear. There is a penske shock on order to address the rear, but once that is on I'm going to open up the stock shock and try and improve it and make it serviceable. I know it can be done...

http://motocd.com/Gallery/Yamaha-Super-Tenere/Super_Tenere_4317
Anything is possible...
 
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