Topic: On Installing XS650 Cartridge Emulators in late model CB550 Forks

[Kong]

Last week I bought a set of inexpensive cartridge emulators from the Mike's SX650 website.  A set cost $50.  They arrived in a couple of days and came with instructions that showed the drilling pattern appropriate for Yamaha forks.  The emulators fit like a glove in the Honda damper tubes with no modifications necessary at all.  I drilled the existing holes in the damper tube out to 5/16" and added two additional holes at 90-degrees to the existing sets.  I didn't cut anything out of the stock springs, I just reinstalled them.  The bike isn't on the road and I don't know what its final weight will be but I expect I will be buying a set of non-progressive replacement springs before it hits the road.

At any rate the instillation went like a breeze, no problems at all and everything fit together very nicely.  I have no idea, and so I'm asking, how much oil to put in the legs (depth from tube-top to oil, fully extended would be even better yet) or of what weight to start with.  Oh, I didn't do anything to the upper rebound holes.  The instructions indicated that at least on the Yamaha front end's damper tubes they were to be left alone and knowing no better I left them alone on my Honda damper tubes too.  I can weld them shut and grind the tube back smooth if they need to be closed, but for now they remain stock.  Any suggestions on that front?

http://www.mikesxs.net/products-19.html#products

[crazypj]

use 10wt about 6" from top with springs out and legs compressed.
 cycle forks through entire travel several times before final measurement.
 I stopped putting measured quantity  of oil in forks about 30+ yrs ago, levels are more important and easier to measure (piece of small bore pipe and a bicycle pump with washer reversed so it sucks instead of blows  )
 You can buy level gauges but they seem to break/wear out pretty easy

[Kong]

6" and 10wt., thanks!  That's what I needed to know.  I've got a turkey baster with a tube on the end that is 'callibratable' with a ruler and a magic-marker that has served me through many a fork.  It is a compliment to Harley Davidson that in their "Service Manual" they give you the oil measurement both ways, as a volume measurement and as a height from tube-top.  I far prefer the later.

Thanks again.

On the emulators, I preloaded them at 2.5 turns and am hoping for the best.

[mjstone]

I just finished rebuilding my forks.  No emulator yet, so will be interested in how yours goes.  I filled my forks to 6" from the top.  I took a long wire twist tie, bent it over at 6", hung it on the edge of the tube and filled till it came up to the tie.

MJ

[bwaller]

Measure oil with emulators in place. Because of the emulator there is automatic preload maybe too much with stock springs. Don't cut them, that will make them stiffer. I bought Racetech springs which are shorter (smaller OD also) and give a chance to add whatever preload the rider needs. I changed to 40lb/in emulator valve springs because the smaller fork spring diameter limits flow somewhat to the valve. 2.5 turns should be ok, you'll need to weld shut at least one rebound hole on the damper rod and maybe even go to 15w oil to reduce rebound. You'll know once you ride it and the oil heats.

[stueveone]

I've got an emulator tuning thread going. . .
I would really weld BOTH holes shut on the damper rod. I'm using 15W fork oil with pretty good rebound.

As far as oil level is concerned, measuring 6" into the tube from the top will get you started for sure. But to get it just right, you'll have to first measure full bottom out and mark it on the fork tube with a piece of electrical tape. Then, secure a zip tie tell tale to the fork tube below the full bottom out tape mark. Then go for a blast around your block hitting the brakes as hard, while safely, as you can. Then pull the bike back into the garage and measure where the zip tie ended up to where the full bottom out tap mark is. It should be no closer than 5mm or 1/4. This will give you the entire amount of travel your forks have to offer without danger of bottoming out.

also: http://www.strappe.com/suspension.html

[Kong]

Steveone,

I have been following your posts with great interest.  In reading the link you provided, particularly the short section on Emulators, its says in part 

"Cartridge emulators have two advantages: improved high-speed compression damping, and the separation of compression and rebound damping adjustments. Rebound damping is set simply by changing the weight of the fork oil (same damping holes for rebound), then the compression damping is set by adjusting the spring on the shim stack."

This doesn't conform to your recommendation to weld the holes shut.  If the holes are gone what effect can oil weight have on rebound dampening?

[stueveone]

"Cartridge emulators have two advantages: improved high-speed compression damping, and the separation of compression and rebound damping adjustments. Rebound damping is set simply by changing the weight of the fork oil (same damping holes for rebound), then the compression damping is set by adjusting the spring on the shim stack."
This doesn't conform to your recommendation to weld the holes shut"

Well I have also read multiple accounts for welding holes shut too, some of which came from the manufacture of emulators.
I was skeptical as well, which is why I didn't weld my rods at first. . . Instead, I took my forks completely apart three separate times, playing around with 10W, 15W, and 20W, and trying welding just one of the holes shut, before finally welding both of them shut.
I'm not sure why there are different opinions on the topic, probably due to different bikes and inherent geometry?
I couldn't say. I just know what I did, and had to do to my CB750 to get the rebound to fall in line. 

"If the holes are gone what effect can oil weight have on rebound dampening?"

Thicker oil still has a more difficult time passing through the forks, around the damper seal, through the emulator,etc thereby affecting both rebound AND compression. If you move to a thicker oil for damping, you have to tune your emulators around that. I am by no means a suspension expert, but with both of my holes welded shut and with 15W oil, the rebound is a lot more well behaved then before (I'm still toying with the idea of trying 20W oil just for kicks to see if that slows it down even more!).

Hope this helps, and keep us posted on YOUR results!


 

[crazypj]

20wt will generally slow things down enough to get severe packing if you hit a series of bumps

[bwaller]

Not to be a smart-ass but MRieck said years ago that these fork valves work well BUT the forks themselves need not to  be worn out. Good advise. Let's face it after thirty odd years we're not starting with new pieces to begin with. 
I figure this has a lot to do with why it's likely necessary to weld both damper rebound holes closed..... but remember, step by step, close one hole first.

To recapture the fork valve I use an extendable magnet, works great.

Don't forget to start at the beginning though, pick a spring and then set preload. I don't mean to sound like an expert either, but it's a rewarding process.

[stueveone]

I have new fork tubes... So the worn out angle doesnt factor in to my scenario. The telescopic magnet is the way to go though. Not sure how else you could actually do it!

[Scott S]

 Interested to know how this turned out.

 Also, any pics of the holes you're talking about welding up? Or anything that shows the installation process?

 Stock springs or

[Bluegreen]

Looking for some advice here.

I recieved my emulators in mail today, and no instructions. No big deal, I'll just hop on to SOHC and see what the trust has to say about the matter. After reading this thread I have a few questions.

First my current setup

CB550
Progressive springs
New fork tubes from Forks by Frank

I seem to have a couple of problems.
1) Progressive springs are not good with these emulators?
2)The new forks were 3/8" longer thank the stock ones for some reason so I have shims in there right now.

Should I track down some straight springs? Any recommendations?
And should I try to get them a little longer or is a 3/8" shim ok?

Hopefully I get a set of instructions soon. Looking at these things I have no idea where the "turns" even start Thanks for any thoughts.

[crazypj]

The instructions are to drill more holes not weld them shut AND RE-DRILL IN DIFFERENT LOCATION
 I think someone has gotten confused over two completely different modifications?

[Doctor_D]

The instructions are to drill more holes not weld them shut AND RE-DRILL IN DIFFERENT LOCATION
 I think someone has gotten confused over two completely different modifications?

Yes, the compression damping system needs to be eliminated by drilling additional holes in the lower portion of the damper, but you also need to weld the tiny rebound holes to improve rebound damping.

As for fork springs, I'm using custom-wound Works dual rates with my cartridge emulator, and they work fine.  Progressives are too soft for my tastes.  If you want to use stock springs, there is a way to get a more reasonable spring rate out of them -- provided they're not completely worn out.

First, measure the free length of the spring.  If it is within spec, it's likely OK.  Use a chop saw or something that will give you a flat end to the spring, much like the stock end.  Remove 1/2" of spring.  Add a 1" long spacer, schedule 40 pvc is fine.  This will give a noticeable, but not excessive, increase in the spring rate.

As for oil weight and volume, with the cartridge emulator adjusted to 5-turns of preload, I found 250cc's of 10wt Redline suspension fluid works well. It is a little short on rebound damping for my tastes, so I may reduce the preload and go to 15wt oil in the future. 20wt Bel Ray was too harsh in this configuration.

[Bluegreen]

I think I'm even more confused 

I'm hoping this stuff will make more sense after I get my hands on a set of the original instructions and then re-read this thread, because it seems like there is a lot of good info in it. Right now I don't even know what the basics with these things are. Not sure what direction they go in. Where do the "turns" start? If I back them all the way up three turns dosen't even get the brass touching the small spring. Do turns start at contact with the spring? Kinda pissed that instructions were not included with the emulators!

But thanks for the help

[bwaller]

I think you said these were MikeXS emulators? It doesn't matter, they install with the emulator spring "up" or inside the fork spring. To adjust, loosen the locknut, then unscrew the bolt until the spring is just loose but touching, this is 0 preload. Tighten the bolt the number of turns you want, I should think 2 or 3 turns on a 550 to start. Don't forget tighten the locknut. On the stock damper rods there is one compression hole near the bottom, The emulator valve will take over this action so enlarge that hole in the rod to 5/16" and drill two more (each 90 degrees from the last) spaced 3/8" apart. The reason for welding shut the two tiny rebound holes in the damper rod is that often the damper rod sealing ring.....doesn't seal well inside the fork tube. So ultimately there are plenty of places oil leaks, plus with those two holes in the rod as well there is virtually no rebound damping. If your damper rod seal is good and the rod slides slowly through the fork tube or needs to be pushed through then only weld one of the holes closed to try.

I'm using straight rate RaceTech fork springs. The issue with progressive springs is just having another variable to try to understand when tuning, I can understand why straight are better with these, but guys here have used others.

One issue with the Mikes emulators is no-one seems to know the valve preload spring tension ( I didn't measure it either but expect it's around 60in/lbs) The racetech springs are smaller diameter and they don't allow the recommended clearance between fork spring ID and emulator valve plate OD. To compensate I bought lighter emulator springs (40in/lb) so the valve opens earlier, and used one less turn of valve preload.

Everyone will have their own preference but I use 15W fork oil. After several trials to get the fork travel I want my oil level is at 175mm. This is measuring from the top of the fork tube down to the level of the oil, That is with fork tube compressed, with no fork spring, but the emulator inside.

If you don't get the instructions let me know & I'll scan mine for you.

A very important step is getting fork spring preload adjustment as well as rear shocks. Check the recommendations for this on the Sonic Spring website or RaceTech as well. It takes some time but you'll be amazed how much better your bike can suspend and handle. Keep detailed notes as you go.

Good Luck.

[verslagen1]

Can some one post the instructions?

[Bluegreen]

I think you said these were MikeXS emulators? It doesn't matter, they install with the emulator spring "up" or inside the fork spring. To adjust, loosen the locknut, then unscrew the bolt until the spring is just loose but touching, this is 0 preload. Tighten the bolt the number of turns you want, I should think 2 or 3 turns on a 550 to start. Don't forget tighten the locknut. On the stock damper rods there is one compression hole near the bottom, The emulator valve will take over this action so enlarge that hole in the rod to 5/16" and drill two more (each 90 degrees from the last) spaced 3/8" apart. The reason for welding shut the two tiny rebound holes in the damper rod is that often the damper rod sealing ring.....doesn't seal well inside the fork tube. So ultimately there are plenty of places oil leaks, plus with those two holes in the rod as well there is virtually no rebound damping. If your damper rod seal is good and the rod slides slowly through the fork tube or needs to be pushed through then only weld one of the holes closed to try.

I'm using straight rate RaceTech fork springs. The issue with progressive springs is just having another variable to try to understand when tuning, I can understand why straight are better with these, but guys here have used others.

One issue with the Mikes emulators is no-one seems to know the valve preload spring tension ( I didn't measure it either but expect it's around 60in/lbs) The racetech springs are smaller diameter and they don't allow the recommended clearance between fork spring ID and emulator valve plate OD. To compensate I bought lighter emulator springs (40in/lb) so the valve opens earlier, and used one less turn of valve preload.

Everyone will have their own preference but I use 15W fork oil. After several trials to get the fork travel I want my oil level is at 175mm. This is measuring from the top of the fork tube down to the level of the oil, That is with fork tube compressed, with no fork spring, but the emulator inside.

If you don't get the instructions let me know & I'll scan mine for you.

A very important step is getting fork spring preload adjustment as well as rear shocks. Check the recommendations for this on the Sonic Spring website or RaceTech as well. It takes some time but you'll be amazed how much better your bike can suspend and handle. Keep detailed notes as you go.

Good Luck.

Thanks man!!

[Bluegreen]

So I pulled a set of 550 forks apart and found two things that differed a little from the descriptions.

1) There are two larger holes 180' apart on the lower section, not one. Should I drill both of those out too 5/16" and and just one more 90' to them and 3/8" up? Basically 3/8" towards the camera from the silver mark in the photo?

2) there is a little rod that prevents the emulator from fitting into the stock damper. Can I just punch this out?

Thanks for the help again!

[bwaller]

Sorry I just cant remember if those damper rods are two pieces pinned together or not. I know I have some of those older rods, pulled two sets of forks apart and they are the later type.

If they are two pieces then punching out the pin is no good. If you don't have any other rods you could remove the pin and slide the outer part off an 1/8" and weld it. Better with other rods or make a 1/2" spacer to sit on top of your rod so the emulator can locate in it.

Here's a pic of what you need to do drilling larger holes. Notice I had welded one rebound hole closed, redrilled it, then welded it closed again later. 

[Bluegreen]

Bwaller, you're the best!

[bwaller]

Hey Bluegreen, check the RaceTech site, I think they offer a spacer for that type damper rod??

[Kemp]

I use the Mike'sXS cartridge emulators in my CB550's as well. They absolutely transform the action, feel, and response of the fork. You get a smooth, supple action with control more like a modern sportbike. Instead of the bike hitting a ripple or bump and then bouncing in the air, the wheel now goes up one side and rides down the other, rough roads are suddenly almost smooth! BWaller has it dead on, forks need to be decent not worn out, late model 77/78 forks have easier to work with damper tubes as the early 500/550 have that pin which must go (good luck there). You drill out the compression holes and add 2 additional like the instructions say, basically you are making the original compression dampening inaffective as your new emulators take over the job. I've even retained stock fork springs in one build as the one inch high emulators compensate for a little "vintage" spring sag and even adds a bit of additional preload. I use 15wt, 160cc with 3.5 turns out on the emulators. The best build was with progressive front springs and emulators as it gave less fork dive under braking and a bit more "feel" in the front end with the stiffer spring. Ride quality was just as good and steering was quicker/sharper also. I will try welding the rebound holes on my next set also as that action might improve as BWaller suggests.

[Bluegreen]

Hey Bluegreen, check the RaceTech site, I think they offer a spacer for that type damper rod??

Got lucky, the dampers I was taking pictures of were from a random 550 set I had kicking around the shop. I wanted to investigate before I ripped my front end open. Which I did shortly after

The ones in my bike were the same as yours in the photo. So I drilled and welded them up. Current set up as follows:

both tiny holes welded shut
6 5/16" holes drilled at bottom
15w fork oil, 175mm from the top
3 turns of pre load on emulator
5/16" of pre load on springs
progressive springs that sat flush with the tops of the forks

It was too damn cold by the time I got it all back together but tomorrow I'd like to go ripping around the neighborhood, see how it feels. I have some stock 550 springs kicking around the shop and want to try them out with different pre loads as well.