Author Topic: Cartridge Emulator install problem and tuning question (Read 9050 times)

stueveone · « **on:** September 06, 2010, 11:02:35 PM »

Hey guys,
So, just came across an issue with the Cartridge Emulator install. . .

Bike: cb750 K4
Emulator Kit: Mikes XS

http://www.flickr.com/photos/22273727@N00/4966339521/

As you can see from the pictures, the point on the dampening rod where the emulator is supposed to just slide right into, there is a set pin that spans the distance! AND to make matters worse, the emulator base is too large to fit in the dampening rod top. WTF!!! Anybody else have this problem?
The solution I found, was to first, remove the middle portion of the pin. I basically removed and then tapped the pin into place enough where it and the emulator nut would not come into conflict, and then cut it with a dremel, punched it a bit further in, and now hope it will not come shooting out, scoring the inside of the fork tube.
Secondly, to remedy the emulator insert being too large to fit into the dampening rod, I busted out the dremel again and machined out the inside diameter to fit that on the emulator. Couldn't have done better if I had a lathe.

So, everything is back together, and just took it for a test run around town. The ride is a bit harsh so now it's time to tune it.
Question. The rebound dampening seems to be a bit fast, as the suspension is rebounding higher before settling back into the normal sag point ie pogo-ing a bit. I remember someone saying something about welding one of the rebound holes? I guess I should have done that? I'm using 15w fork oil, maybe trying 20w and then adjusting the emulator? Or should I just weld one of the rebound holes?
Any suggestions?

Steve_K · « **Reply #1 on:** September 07, 2010, 05:44:15 AM »

Rebound damping is controlled by oil weight (10w less rebound, 40w more rebound) I suggest using fork oil.
Compression damping controlled by spring tension of emulator. More spring tension(more compression damping). Use one of those grabbers you to remove the emulator.
Steve

stueveone · « **Reply #2 on:** September 07, 2010, 11:08:37 PM »

Wouldn't 10w have more rebound since it is able to go through the rebound holes on the dampener more easily? And more viscous 40W oil would in turn slow things up as it is thicker?

Bodi · « **Reply #3 on:** September 08, 2010, 06:01:41 AM »

more and less refers to the amount of motion damping, not the rebound speed.

stueveone · « **Reply #4 on:** September 08, 2010, 10:47:20 PM »

So if we are talking about rebound speed, in regards to the 2 rebound holes on the damper rod, would thicker oil rebound faster or slower? ie, I'm running 15w currently, and the front end rebounds up past the normal ride height before leveling out again. So, would 20w oil make my forks rebound more slowly?

Steve_K · « **Reply #5 on:** September 09, 2010, 04:02:36 PM »

Yes, thicker oil moves slower thu the holes. Be sure that the oil level is above the damper in the forks. If it is exposed to the air, the oil will froth and reduce damping(rebound faster).
Steve

stueveone · « **Reply #6 on:** September 09, 2010, 05:59:14 PM »

Thanks for your help guys. I'll post my progress.

MRieck · « **Reply #7 on:** September 09, 2010, 06:11:53 PM »

Weld (or braze) closed one or both of the rebound holes. I have done this on various bikes including my FJ1200 (2 on each rod welded shut). You will get into silly weight oils to try and correct the rebound if you do not close them

stueveone · « **Reply #8 on:** September 10, 2010, 08:02:46 PM »

Thanks mrieck. Yes, I think I'll start with welding one and then adjust the oil weight after.

stueveone · « **Reply #9 on:** September 19, 2010, 10:45:26 PM »

Update: Welded one of the rebound holes closed. The setup is much better, but still slightly rebounds a bit too much. Now it is time to dial in the rest with heavier fork oil. I'm running 15W currently, so I'll try 20W next.
Also, a suspension side note: I'm dialing in the suspension sag. I removed 1/2 of preload and in turn went from a very stiff 27mm to a little too cushiony 39mm. I will add washers until I get 35mm.

stueveone · « **Reply #10 on:** November 16, 2010, 10:38:16 PM »

Ok, so just put in 20w oil in my forks. The rebound speed seems fine, but the forks still rebounds up past the ride height before settling back down. I guess MRieck's suggestion of welding that second hole would have been a good idea after all. Anybody else have any other suggestions before I tear apart the fork once again?

Also, I used a standard hardware store washer for setting preload. I'm at about 36mm now which is good enough for me.

stueveone · « **Reply #11 on:** November 20, 2010, 06:01:37 PM »

Just soldered the remaining hole (1 each rod) with metal works solder and flux from Home depot. Back down to 15w oil and it's raining like mad outside so I can't test. Right off the bat, however, I think I've got a bit too much oil as the forks seem stiff, and as my hard braking simulation would suggest, I still have a good 40mm between the slider zip tie and bottoming out. Hopefully I can get some road time in tomorrow.

stueveone · « **Reply #12 on:** February 15, 2011, 11:28:03 PM »

Ok, new fork tubes from a K7-K8 bike ( so I can mount a fork brace) and went from progressive springs to stock springs cut about an inch (the emulators act as preload by about the same amount)
After a few miles test ride, the front end just seemed a bit smoother and more solid. This is due to either 1. the new longer tubes are over and inch longer so less friction, and/or replacing the springs.
I had read that you are supposed to use standard l wound springs with emulators. Though, I have also heard of a few people using progressive springs.
After tonight, I would have to agree with using standard wound springs over progressive springs.

fastbroshi · « **Reply #13 on:** February 16, 2011, 03:13:33 AM »

I think you hit the nail right on the head Steve. If Racetech suggests straight wound springs, I'm gonna go with that.

Kong · « **Reply #14 on:** February 16, 2011, 12:36:39 PM »

Steveone,

I've been following this with great interest and in fact ordered a set of the emulators from XS650 the other day; I expect them to arrive friday. My front end was already apart so I pulled out the dampers today. Mine ('77 550k) don't have a pin inside, so no problem there. I have access to a lathe/machinist so if the damper is too small in diameter to accommodate the the emulator I can have the hole enlarged - would an O-ring at the top of the damper make any sense?

My question about your current setup - aside from how do you have it adjusted - didn't I read in another post that you began with it '2 turns in' or something like that - is this. Did you close off both of the upper small holes, I believe you called them rebound holes, and what kind of drilling did you finally end up doing at the bottom end of the damper? If I understand the things correctly that's what you do, drill larger or more holes in the bottoms, and then according to your writeups you also have to block the very small (2 of them) upper holes. Is that correct? I'm just trying to get it in my mind what I'm going to have to do to put these things in and get them somewhat close to right to start with. The bike won't be running for at least another 6 weeks, there's lots more to do, so I just want to get this done and behind me. Any hints you can give on setting it up will be much appreciated.

Oh, right now I intend to cut the springs first to equal the height of the emulator, and then maybe cut a but more out of them and make a plug for the top. I'll measure first to make sure I don't get spring bind, but my idea was that if I was going to cut them anyway to at least cut from the progressive end out of the spring.

Steve_K · « **Reply #15 on:** February 16, 2011, 05:01:31 PM »

Race-Tech sent very good instructions for the Suzukis I put them in. I had no problem and followed the setup with oil weight, setting on the small spring on the compression damper adjuster, and fork preload. I messed around with sag until I got the feel I wanted.
Note: for my bikes I did not have to close rebound hole. You will have to drill 3/8 or 5/16 holes in the damper, but not difficult.
You will like the results.
Steve

wannabridin · « **Reply #16 on:** February 16, 2011, 05:10:40 PM »

Race tech told me just one hole needed to be brazer shut, but I've heard from Voxonda and others to braze them both while drilling the bottom out larger. Im leaning towards doin both of them, but I can't decide yet.

jaguar · « **Reply #17 on:** February 16, 2011, 07:00:16 PM »

funny the mikes XS ones say to Drill the holes......

wannabridin · « **Reply #18 on:** February 16, 2011, 07:04:01 PM »

he's talking about the ones on the bottom i'm sure. opening up the holes up top would only allow the oil to bypass the emulator, negating its function entirely!

jaguar · « **Reply #19 on:** February 16, 2011, 07:17:24 PM »

was just going to post that yes we are talking about different holes.....

on a side note.

would using a longer damper rod do anything positive for the suspension?
i have a set of rods from a 35mm DOHC forks. just wondering

wannabridin · « **Reply #20 on:** February 16, 2011, 07:29:01 PM »

i don't think it would give you anymore preload, as the lower spring seat is still in the same position... it could affect the rebound since the oil has to travel a little farther distance, and cause it to lose a little bit of the fluid "head" energy it had, but i doubt it'd be noticeable or even exist at all

stueveone · « **Reply #21 on:** February 16, 2011, 08:10:32 PM »

"I've been following this with great interest and in fact ordered a set of the emulators from XS650 the other day; I expect them to arrive friday. My front end was already apart so I pulled out the dampers today. Mine ('77 550k) don't have a pin inside, so no problem there. I have access to a lathe/machinist so if the damper is too small in diameter to accommodate the the emulator I can have the hole enlarged - would an O-ring at the top of the damper make any sense?"

No, I don't think it would do a great deal. The springs are pressing down on the emulator to seal it to the damper rod. It's interesting, the K7-k8 damper rod hole, while being large enough to fit the emulator, is actually a bit larger in comparison to my exact fit machined-out pin style damper. So, in this last install, I still am rocking the older style damper. Can anybody with MikesXS or Racetech emulators corroborate this claim of the emulator having a bit of "slop"? I should have measured the difference while it was apart. $:-\$

"My question about your current setup - aside from how do you have it adjusted - didn't I read in another post that you began with it '2 turns in' or something like that - is this. Did you close off both of the upper small holes, I believe you called them rebound holes, and what kind of drilling did you finally end up doing at the bottom end of the damper? If I understand the things correctly that's what you do, drill larger or more holes in the bottoms, and then according to your writeups you also have to block the very small (2 of them) upper holes. Is that correct? I'm just trying to get it in my mind what I'm going to have to do to put these things in and get them somewhat close to right to start with. The bike won't be running for at least another 6 weeks, there's lots more to do, so I just want to get this done and behind me. Any hints you can give on setting it up will be much appreciated."

I would highly recommend welding, soldering, brazing, (i'm still thinking JB Welding would work) BOTH rebound holes closed. I went up to 20W oil trying to calm down the speed at which the forks rebound upwards. I'm currently running 15W oil with pretty ok results. I need to play around with the suspension a little bit more to know for sure, but I will keep posting results.

And yes, you drill a total of six 5/16 holes that are at least 10mm apart, at the bottom of the damper where the old compression holes are located.

"Oh, right now I intend to cut the springs first to equal the height of the emulator, and then maybe cut a but more out of them and make a plug for the top. I'll measure first to make sure I don't get spring bind, but my idea was that if I was going to cut them anyway to at least cut from the progressive end out of the spring."

I would not use progressive springs. If you can find an old pair of stock springs, cut those guys to fit (this will in turn stiffen the spring) and use hardware store washers or pvc to adjust preload. When cutting the springs, I used a dremel to cut straight across first, then finished them up on the bench grinder to make them as flat as possible. Make sure to then install this cut side up at the top where the fork tube cap is. Also, I would err on the side of cutting a shade more than less, because it is far easier to just add a washer than have to take the springs out completely and cut them again.

stueveone · « **Reply #22 on:** February 16, 2011, 08:14:10 PM »

"would using a longer damper rod do anything positive for the suspension?
i have a set of rods from a 35mm DOHC forks. just wondering"

It would give you identical preload (unless the damper rod top is somehow taller). However, it WOULD give you more travel as well as raise the front ride height by however much longer it is. In a sense, it is the exact opposite of doing the ol spacer between the damper rod and fork bottom trick.

mjstone · « **Reply #23 on:** February 17, 2011, 09:45:57 AM »

I'm watching with interest! I am in the process of replacing my 500 forks with 550 forks so that I can do a dual disk brake upgrade. My damper rod has the cross pin in it like yours. I am thinking of doing the cartridge emulators as well, so I am hoping that your cutting of the pin works well. What would other options be if this does not work?

MJ

Kong · « **Reply #24 on:** February 17, 2011, 03:14:57 PM »

I can tell you what I was going to do if my damper tubes would have had the pins, I was going to drill them out from the sides and then weld the holes back shut, hit it with a grinder and then act like they never existed. That is how I'm going to seal the two rebound holes too, just pop it with the welder and then grind it smooth if necessary.

Last night I was sitting here with the damper in one hand and the oil lock in the other and like a silly little monkey stuck one inside the other. With the oil lock in place over the damper I immediately noticed that the two bottom holes in the damper were partially (~50%) covered. So I thought to my self, why would the honored engineers at Honda drill those holes and then partially cover them - permanently? Made no sense to this old baboon.

stueveone · « **Reply #25 on:** February 17, 2011, 05:07:36 PM »

" My damper rod has the cross pin in it like yours. I am thinking of doing the cartridge emulators as well, so I am hoping that your cutting of the pin works well. What would other options be if this does not work?"

Eh, just cut the pin and call it good. Mine hasn't budged in the slightest.
Machining out the inside of the damper rod to fit the emulator is a bit more tricky. But if you have Dremel skills totally doable. And, again, judging from the slop of the later model damper rod, it doesn't appear necessary to worry if it is a tight fit or a shad loose although I personally would have to think a well machined fit would be best.

Doctor_D · « **Reply #26 on:** February 21, 2011, 06:32:31 AM »

Ahhhh, so that's why I have a harsh top-out problem with XS emulators and Works springs - rebound holes need to be closed up. 20wt Bel Ray suspension fluid was giving me lots of compression damping but didn't seem to have much if any effect on rebound.

Can we see a picture of a brazed or soldered damper-rod?

stueveone · « **Reply #27 on:** February 21, 2011, 07:17:13 PM »

I think there are photos around here somewhere. Not much to look at. Just looks like solder in holes. Just make sure you sand it flush and for the love of pete de-bur those larger holes and polish them if you are so inclined!

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Author Topic: Cartridge Emulator install problem and tuning question (Read 9050 times)