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Strange Base Valve and Shim Arrangment

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Hello

Just looking for your thoughts on this Base Valve arrangment.

I have an 07 Gas Gas EC 300 with Mazzochi 45mm Shiver forks. When I first purchased the bike I noticed it had a habit of pushing right through the fork stroke way to easy but at the same time sharp hits from roots and rocks made it deflect badly to the point of being scary. Winding the compression clickers in just made no difference.

I decided after reading the Mazzochi manual on this fork to decrease the airgap to 90mm and this had a huge effect on the fork the diving and bottoming disapeared and I could set the clickers about mid way and now I can feel adjustments of 2 clicks. The trouble was the quick sharp hits are still there and it's still scary at speed but I kind of grew to live with it.

While changing the fork oil recently I pulled the base valve apart thinking I may be able to make some shim adjustments to solve the problem. What I found was quite odd, the valve has 4 ports that look to be small at 3mm dia. also there is a bleed hole drilled in the side of one port about 2mm dia. Now the shim stack.

11x.2 ? bleed shim

22x.1

11x.2 ? crossover

20x.1

19x.1

11x.1 ? crossover

18x.1

17x.1

16x.15

14x.2

12x.2

The way I see it the valve has way too much free bleed probably why it pushed through the stroke and the small ports may be restricting oil on the sharp hits causing the harsh feel. I just can't see the shims having much effect in this set-up.

I thought I might try re-arranging the shims to the following but the port size and bleed hole is still a worry.

22x.1

20x.1

19x.1

11x.1

18x.1

17x.1

16x.15

14x.2

12x.2

Sorry for the long post but I thought I had better provide as much info as I could.

Any thoughts thanks Andrew.

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11x.2 ? bleed shim

22x.1

11x.2 ? crossover

20x.1

19x.1

11x.1 ? crossover

18x.1

17x.1

16x.15

14x.2

12x.2

This stack is absolutely too soft no damping at all. It is common that there is a bleed shim but it should be 0.1 thick. First cross over is too thick and there is only one face shim. Your new stack is much better. You should get std stack, it will make this much easier. Marzocchi recommen to use 7,5W oil.

This stack is std gas gas stack, don't know model or year

22-0.1 (6)

11-0.2

21-0.1

19-0.1

18-0.1

17-0.1

16-0.1

15-0.1

14-0.1

12-0.1

Jusa

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Hello

Just looking for your thoughts on this Base Valve arrangment.

I have an 07 Gas Gas EC 300 with Mazzochi 45mm Shiver forks. When I first purchased the bike I noticed it had a habit of pushing right through the fork stroke way to easy but at the same time sharp hits from roots and rocks made it deflect badly to the point of being scary. Winding the compression clickers in just made no difference.

I decided after reading the Mazzochi manual on this fork to decrease the airgap to 90mm and this had a huge effect on the fork the diving and bottoming disapeared and I could set the clickers about mid way and now I can feel adjustments of 2 clicks. The trouble was the quick sharp hits are still there and it's still scary at speed but I kind of grew to live with it.

While changing the fork oil recently I pulled the base valve apart thinking I may be able to make some shim adjustments to solve the problem. What I found was quite odd, the valve has 4 ports that look to be small at 3mm dia. also there is a bleed hole drilled in the side of one port about 2mm dia. Now the shim stack.

11x.2 ? bleed shim

22x.1

11x.2 ? crossover

20x.1

19x.1

11x.1 ? crossover

18x.1

17x.1

16x.15

14x.2

12x.2

The way I see it the valve has way too much free bleed probably why it pushed through the stroke and the small ports may be restricting oil on the sharp hits causing the harsh feel. I just can't see the shims having much effect in this set-up.

I thought I might try re-arranging the shims to the following but the port size and bleed hole is still a worry.

22x.1

20x.1

19x.1

11x.1

18x.1

17x.1

16x.15

14x.2

12x.2

Sorry for the long post but I thought I had better provide as much info as I could.

Any thoughts thanks Andrew.

You are correct in your assumptions. Those forks have way to much bleed.

To make matters worse the mid is usually a check plate.

personally I would address the mid valve in addition to the base. This will allow you to run lower oil levels and hold the fork up in the stroke and will aid in the fork blowing through the stroke...

You can try something like this first

22.1(2-3)

20.1

16.1

14.1

11.25.

11.25

Edited by russ17

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i have never seen a fork with so much bleed,

mid is a check plate

base has a 0.2mm bleed shim and a bleed hole of 2mm(huge)

base has a cross over after one face shim....then another in the hs stack, what were they thinking?

7.5 wt oil would help but i bet you could run a 15wt in that fork with a std valve stack and it would still be too plush.

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i have never seen a fork with so much bleed,

mid is a check plate

base has a 0.2mm bleed shim and a bleed hole of 2mm(huge)

base has a cross over after one face shim....then another in the hs stack, what were they thinking?

7.5 wt oil would help but i bet you could run a 15wt in that fork with a std valve stack and it would still be too plush.

I have no clue :thumbsup:

But I wish they would explain their thoughts in their designs, theory..

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I raced a gas gas 250 ec in 2005 and my knees used to hurt........lots

It was so soft it was like my knees were the damping...

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Thanks

It makes me feel better that you guys confirm it,s such a wierd valve set up. I didn't mention in the previous thread but the rebound also has the bleed hole along with the bleed shim along with a base shim that will not quite cover the full port surface of the valve.

And before anyone asks these valves have never been apart ever so this is how it came from the factory.

After talking to my local suspension tuner who scratched his head a lot we came to the decision that the standard valve may take to much effort to get working properly so a more easily tuneable aftermarket valve may be the go he is reasonably confident in getting the rebound valve to work in conjunction with a different base valve.

Is there any Gas Gas or Husky owners out there with the 45 Shivers that have ever seen this set up.

I'm starting to think someone on the Marzzochi assembly line was playing games. :thumbsup:

Thanks Andrew.

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Are you certain they haven't been fiddled with??????? Ditch the check valve, smooth out the compression and build a mid valve. Did it on my BM. Pretty slap happy but felt much better.

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Are you certain they haven't been fiddled with??????? Ditch the check valve, smooth out the compression and build a mid valve. Did it on my BM. Pretty slap happy but felt much better.

:thumbsup:

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Thanks for the replys.

No never fiddled with bought it new off the showroom floor odd!!!

The check valve you refer to is that the thick shim on the top side of the piston and is this where you build the mid valve?

Any suggestions on shim sizes in the mid valve as I will need to purchase a few to complete this project.

Thanks.

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here ist the original GG EC 250 2006 Base valve stack

Marz. Shiver 45

12 x 0,20

13 x 0,20

14 x 0,15

14 x 0,15

15 x 0,15

16 x 0,1

16 x 0,1

11 x 0,1

17 x 0,1

19 x 0,1

11 x 0,2

22 x 0,1

11 x 0,2

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You are correct in your assumptions. Those forks have way to much bleed.

To make matters worse the mid is usually a check plate.

personally I would address the mid valve in addition to the base. This will allow you to run lower oil levels and hold the fork up in the stroke and will aid in the fork blowing through the stroke...

You can try something like this first

22.1(2-3)

20.1

16.1

14.1

11.25.

11.25

If you did this (added the mid-valve), would you soften the base valving, or leave it as is ?

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If you did this (added the mid-valve), would you soften the base valving, or leave it as is ?

Actually we are running a midvalve setup with something similar to this, its a tad stiffer base setting than posted.

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