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Unknown Piston: Showa Shock/Honda CRF 250 09

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I see you from Germany. Does it come with a grey loose piston band? I belive this a C2P piston sold from S-tech. PM me the stack or post it here.

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hey bang,

yes there are c2p stickers on the bike (fork, but the fork is stock).

The bike got some "factory clicker adjuster" :-D

p1040259j.jpg

By vietze at 2011-12-11

And yes, you're right with the pistonband.

I already looked up the S-tech store and didnt find this design. Also the c2p homepage wasnt any help.

I'll PM you!

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Not all the pistons are showed on the S-tech website. I will check what I got in the shop and let you know.

Bang

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comp

3x44,25

2x44,2

23.2

38.15

44.25

42.25

40.25

38.25

36.25

34.25

32.25

30.25

28.25

26.25

24.25

22.3

reb

2x40.2

24.1

38.3

36.3

34.3

32.3

30.3

28.3

27.25

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This is about the second time I have seen a cross over set up like this set up in a reverse fashion and as much as I dare say this what is the reasoning?

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I've noticed that too here and i recently saw it on another stack.

At the very first glance I thought it was a tipping error, but it wasnt.

Well, I'm no expert... my thoughts:

What would be, if you swap it to the "traditional way".

LS gets a bit stiffer because the 38.15 acts as a bending shim for the LS stack. Space for the 44er LS-Shims to hit the next 44er:

.15 + 0.2 = 0.35

So lets look at that one here:

LS is softer, but the 38.15 now belongs to HS (midspeed?!).

BUT there is still the 0.35 gap for the LS shims to bent before they hit the first shim of the HS stack.

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it looks to me a way of controlling progression into hs , a normal stack is either contacting or not , this one seems to add a step in between ?

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it looks to me a way of controlling progression into hs , a normal stack is either contacting or not , this one seems to add a step in between ?

I'm sure it does limit port growth and would aid to the HS within a certain velocity range.

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Like russ17 said flipping the crossover is going to make the stack stiffer.

1-stacks.png

But the difference is really small.

2-area.png

Zooming in you can see the difference between the two stacks.

3-area-zoom.png

Most of the difference is at low speed before the crossover closes. The difference in low speed flow area for the two stacks is about two clicks on the rebound needle

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Thanks Click for posting this. I was going to ask that you comment on this, so you must of been reading my mind.

I new it had slightly more impact on the LS

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I am surprised it made any difference at all. The stack had three 0.25 face shims plus another pair at 0.2 mm. The crossover had a thickness of only 0.15 mm.

My guess would have been zero difference. But, considering the thickness cubed rule, the 0.15 mm shim adds about a 5% to the face shim stiffness so I guess it makes sense.

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Thanks for sharing clicked!

So, the piston is whether a c2p nor a GoldValve.

I asked people who are dealing with the pistons. Both said it's not there stuff, but looks quite similar.

Which company copies pistons?!:bonk:

Well, in fact it is not so important to know that but I'm curious.:smirk:

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