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Adjust fork compression


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Bodoe

 
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Adjust fork compression

Sat Jun 03, 2006 7:11 pm » Post: #1 » Download Post

After a days riding at a track I noticed that my spuspension needed to be looked after. The back suspension only needed some adjustments but the forks was in need for some more attention.

While reassembling the forks I came to think about the compression, since the rebound has a adjustiing screw as well as the preload, but I could not find out how to adjust the compression. So is there any of you guys who knows how to adjust it? Not that I really need to, I'm just curious. Smile
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j911brick

 
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Sat Jun 03, 2006 9:23 pm » Post: #2 » Download Post

Aside from revalving, you can play with the oil wieght and quantity.
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Wrench.

 
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Sat Jun 03, 2006 11:19 pm » Post: #3 » Download Post

Yeah, what he said.
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Fluffy Cat

 
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Sun Jun 04, 2006 6:57 am » Post: #4 » Download Post

There are a couple of things you can do depending on your weight.
I am about 100kgs all up, that includes all the gear.
The standard forks are passable on the road but if you weigh a bit more than 60-70kgs they are going to slow you down at the track.
My sp forks as standard were not to bad until braking into bends off the straight.
Lots of chatter and bouncing off the bump stops.
So i changed the springs to hyperpro used 15wt oil cant remember the air spring length at the mo but its in my notes and can get it if you want as its quite important ref the chatter.
Next you can strip the fork and remove the valve for rebound and damping at the bottom of the cartridge. Its on a screw thread and the end of the thread is peened over but can be ground off.
On the valve is a shim stack now this bit involves a few different size shims and washers but in the end we used a almost but not quite the same size extra shim. Slightly thinner, on the stack this was on top of the standard shim.
This made things a bit firm and still worked well with the 15wt oil but you could change that if you want.
When you reassemble the valve make sure the screw thread is free of oil and use some thread lock to stop it comming undone.
No chatter and the adjustment is more pronounced ie it now works in a noticable way.
Not hard to do and most workshops that do suspension can get the shims. The motocross tuners are good for this and thats where i got mine.
Have now changed the forks to RVF ones and am redoing those.
Hope this helps.
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Bodoe

 
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Sun Jun 04, 2006 8:29 am » Post: #5 » Download Post

Sounds like a lot of work for a couple of "fully adjustable" forks. Why cant they be as other forks, compression on one leg and rebound on the other.

Well, there were some things i didn't quite get. Perhaps someone could give a breif explenation of these words.

revalving
chatter
air spring length

valve for rebound ... = http://www.dreamgate.ne.jp/nsr/technical/fork12.jpg ???

My problem is that my farings scratches against the track while taking corners. Something I don't fancy that much...The rebound was totally wrong adjusted.

THANKS FOR ALL THE HELP SO FAR! Very Happy
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Dave Ett
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Sun Jun 04, 2006 12:10 pm » Post: #6 » Download Post

I had my forks setup by a professional, who took my weight and set the springs accordingly. Made an amazing difference.

And why aren't they like other forks? Because they're old and Honda didn't think it neccessary I suppose.
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Wrench.

 
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Sun Jun 04, 2006 3:39 pm » Post: #7 » Download Post

valve for rebound ... = http://www.dreamgate.ne.jp/nsr/technical/fork12.jpg ???


That is what is known as your base valve (at the base of the forks). On these type of forks, it handles your compression valving adjustment. If you unscrew the bolt from the bottom piece in the picture, the valve will come off. You will have the valve and a stack of shims, a spacer, and a small spring. Carefully separate all these in the exact order they are stacked. The top side of the valve has the check plate and spring that opens to allow fluid refill on rebound, but does nothing for the rebound damping. The other side of the valve is your compression damping shimstack.

If you want some better valving specs, I can help you build the stack a bit better. I can at least set you up with the stock RS shimstack setup they used in the RS with 41mm conventional forks.

The rebound valve is attached to the bottom of the rod that attaches to the fork cap and extends inside the cartridge. You shouldnt have to touch this, the rebound is valved just fine on this bike.
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Matt@TYGA
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Mon Jun 05, 2006 9:27 am » Post: #8 » Download Post

As it was said. Re-shimming the comp is a good way of firming up the front end. It's set deliberately soft so that road riding is nice and smooth.

On Paul's MC21 (Paul@TYGA, not Wrench!) I set up the front with twin stack compression, didn't touch the rebound stack (just the clickers), HRC option springs and 135mm oil height (no spring, fork compressed) with 10W Showa oil. Works a treat for doodling down the street, or fast, back lane scratching. Paul won't go on the track for fear of crashing, but it's more than adequate for what he wants. He's about 100kgs in his togs, ready to rock.

The twin stack offers supple damping at slow speeds, but firms up nicely when things speed up.
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injected

 
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Thu Jul 03, 2008 2:15 pm » Post: #9 » Download Post

Matt@TYGA wrote:...HRC option springs...


Sorry to bring up such an old thread, but can someone tell me what rate the HRC 'option' springs are, and whether they are still available from Honda for the MC21?
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