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Author Topic: Cartridge Emulator Installation  (Read 894 times)

AgentX

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Cartridge Emulator Installation
« on: September 08, 2012, 03:04:55 PM »
The following is pasted verbatim from my post on Ace's page; thought it might be of interest.  Apologies for a lack of pics on my end, but the instruction sheet with the product has a good set of diagrams.  (Edit:  I just attached it to this post)

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Long time coming, but I finally installed the YSS cartridge valve emulators.

Executive summary--FANTASTIC! But you may need to do a little more work than just pop them in. Still a hell of a lot easier than a front-end swap.



Background:

I've seen reference to them as a Racetech clone but I have no personal idea, and don't know how much the Racetechs cost. These were $135, plus $10 for cutting
me some spacers. Believe they're made overseas. (Thailand, I think I once read?)

My fork is the old-school Bullet fork from the 1977 model year, with the screw-down oil seals. Can't speak for all bikes with all forks, obviously, but most of the Bullet forks seem to share the same basic configuration and operation.

I took measurements from a disassembled fork and Klaus at YSS tech support in NJ told me the 29mm would be a perfect fit.  (AMENDMENT:  The 29mm valves will not fit in the disc fork I just tried to transfer them into!  Looks like 28mm or less will be necessary; next size down seems to be 26.5mm.)



Installation:

Basically, the procedure is to drill extra holes in the pumping rod ("hollow stud" or "spring stud" in the fork leg in most Bullet technical manuals) to allow oil to move freely; the cartridge emulator then provides all your damping via a speed-sensitive shim stack. On the Bullet, you drill out the existing bottom hole to 8mm (or 5/16") and then add three more 8mm holes on top of it.

The emulator itself is a small cylinder with an adjuster screw coming out the top. It sits on top of the pumping rod and under the spring, trapped by light spring tension at rest. Because of the nut on top of the pumping rod, you need to add a cylindrical spacer to give the emulator a place to sit. (Some other makes' rods have a cupped shape on top, so they don't need this.)

Klaus provided me PVC spacers, but they ended up being 1) too thick-walled, and covered up the existing rebound valving holes 2) too short, according to Klaus, when he saw how the rebound system operated; he said the oil needed more space to flow. So I got thinner steel ones machined...17mm high, about 1.5mm-thick
walled. They fit perfectly.

So, the valve was around 14mm tall IIRC, and the spacer was 17. Obviously, this height shoved under the spring was going to add an intolerable amount of preload to the spring. I simply had the springs cut to correspond and ground flat again, taking the spacer/emulator stack height off the top portion of the coil. This portion is static; the coils are touching one another and don't add anything to the operation of the suspension, so it's no-loss.

In reassembly, I used 200ml of 20wt Motul fork oil. 20wt is all I can find locally so I gave it a shot.



Initial Evaluation:

When I got the front end buttoned back up, I was a bit concerned. It felt like a rock at first. But you need to remember suspension is not designed to feel good sitting still. (A common problem with mountain bike suspension...they under-spring and under-damp because they know most punters will just buy whatever feels squishy on the showroom floor!)

I was a bit cautious for about 30 seconds on the test ride before I was blasting over speed bumps at a pretty shocking speed [Enfield-relatively speaking...]  The speed sensitivity of the valving is obvious once you're moving. Took the rough choppy stuff and big humps just fine at speed. I picked my way down some ledges and steps, and the bike took them nicely...soft landing with good
progression mid-stroke.

The valves were set with 2.5 turns preload on the shim stack adjuster screw(2 being the stock recommendation for lighter riders...I am 160 lbs.) Oil weight is the only way to control rebound and the 20wt was suitably fast.

Overall, a rider on smooth pavement might like a bit more cranking on the adjuster screw, or maybe a higher oil height for greater progression, but for India's chopped-up roads this setting felt great for a start. The front of my bike feels better than the Hagons on the back now.

Unfortunately, you need to open up the fork to change settings, but even as it is, it's a massive improvement, so I will likely ride it like this until my new fork bushings show up. Then I'll add a turn of preload and see how it does.

I'll re-post if there are any future problems or revelations.


Website for the product is: http://www.yssusa.com/products_yss_pdforkvalve.html
« Last Edit: March 18, 2014, 03:38:41 AM by AgentX »

basanti

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Re: Cartridge Emulator Installation
« Reply #1 on: September 09, 2012, 07:01:49 PM »
This is fantastic news! Thanks for sharing AgentX  !  I'm very interested cuz I'm not happy at all with the shocks on my bike. Have you noticed if the the heavy diving when breaking hard has lessened after the up grade?

AgentX

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Re: Cartridge Emulator Installation
« Reply #2 on: September 10, 2012, 05:25:24 AM »
Yes, there's less dive now.  I never had a lot of it before, but my fork (it turns out) had some elastomer top-out bumpers installed, which decreased shock height and increased preload...this may have helped me in that regard, even prior to the installation.

You can tune the valve, so you can stiffen the damping if that's your preference.

The valve doesn't have separate high speed and low speed compression damping adjustments, however, so you can't really tune out brake dive specifically without making the fork overall less compliant.  Generally, I'd guess that only top-end super-modern bikes have separate high and low speed compression circuits. 

cafeman

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Re: Cartridge Emulator Installation
« Reply #3 on: December 30, 2014, 12:58:53 PM »
OK, time to resurrect another old thread! There seems to be maybe two members here that have any experience with installing emulators on these bikes. Searched and searched for any info on specific part# or what other make/models for these emulators from YSS. Can't seem to find any mention other than the diameter is 29
mm, for 35mm forks. Also read somewhere about ones from MikesXS : https://www.mikesxs.net/product/27-1086.html So one would assume emulators for 1977-84 Yamaha XS650's will fit. But a YSS part# and knowing the specific make/models they fit (as there is no mention of R-E) would help for others future reference.  ;)
Current Fleet: 2001 Royal Enfield Bullet 500 Cafe Racer
                     1996 Yamaha Seca II
                     1991 Husqvarna 350WXE
                     1991 KTM 250MX
                     2004 Husqvarna TC450

AgentX

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Re: Cartridge Emulator Installation
« Reply #4 on: December 30, 2014, 09:24:06 PM »
YSS sells them by diameter.  There's nothing make/model-specific about them.

As noted in my post, the 29mm fit my first drum brake fork and the 26.5mm fit the disc fork.  That is the only spec you need to know to order them from YSS.

cafeman

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Re: Cartridge Emulator Installation
« Reply #5 on: December 31, 2014, 05:50:35 AM »
YSS sells them by diameter.  There's nothing make/model-specific about them.

As noted in my post, the 29mm fit my first drum brake fork and the 26.5mm fit the disc fork.  That is the only spec you need to know to order them from YSS.
Got it. I forgot to mention Racetech as the other option. Those 29mm emulators fit other bikes though. THAT is what I want to know. Some may buy YSS, others Racetech, maybe some new unknown off brands, some may buy them direct, online, on Ebay, or at a swap meet. Always good to know what other bikes they fit.  :)
Current Fleet: 2001 Royal Enfield Bullet 500 Cafe Racer
                     1996 Yamaha Seca II
                     1991 Husqvarna 350WXE
                     1991 KTM 250MX
                     2004 Husqvarna TC450

High On Octane

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Re: Cartridge Emulator Installation
« Reply #6 on: January 01, 2015, 04:43:16 PM »
I have looked into these before but never pulled the trigger.  But this thread being brought back up got my curiosity brewing again.  One reason I never pulled the trigger on these is because it seemed like a big PITA to install and set up.  But I've been reading all the tech support for these at RaceTech for the last 30 minutes and it actually seems really simple to do.  Especially considering that I have a whole other bike with another pair of forks that I can build off of the bike and then just swap out the legs.  I even have a brand new pair of fork springs from H's that I never installed because I didn't feel like making spacers at the time.  And actually, Metal Supermarket is literally just around the corner from work and they cut everything to spec for your needs.  So I bet I could just take one of the fork assemblies down there and have them cut me a few different spacers at different lengths for $10-$20.

For those who are still trying to wrap your head around this mod, here is the RaceTech fitment guide with illustrations that make it much easier to visualize what is going on.


http://www.racetech.com/download/IP_FEGV_FIT_web.pdf
Scottie J  ~  Bulldog Kustoms Denver  ~  1958 Enfield/Indian Trailblazer  ~  1959 Enfield/Indian Chief

High On Octane

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Re: Cartridge Emulator Installation
« Reply #7 on: January 01, 2015, 05:13:56 PM »
AgentX - I do have a question for you.  Does the emulator sit on top of the fork spring perch on top of the damping rod?  Or does the emulator replace the spring perch?
Scottie J  ~  Bulldog Kustoms Denver  ~  1958 Enfield/Indian Trailblazer  ~  1959 Enfield/Indian Chief

mattsz

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Re: Cartridge Emulator Installation
« Reply #8 on: January 01, 2015, 08:28:14 PM »
And actually, Metal Supermarket is literally just around the corner from work and they cut everything to spec for your needs.

 :o

You effing guys and your living in civilization...  spoilt, I tell you!  ;)

AgentX

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Re: Cartridge Emulator Installation
« Reply #9 on: January 01, 2015, 08:35:39 PM »
AgentX - I do have a question for you.  Does the emulator sit on top of the fork spring perch on top of the damping rod?  Or does the emulator replace the spring perch?

It sits just as in the Racetech .pdf you attached.  Since the Enfield damping rod is flat on top rather than cupped, you need to use a short tubular spacer under the emulator for it to sit in.

Springs need to be shortened to correspond to the added height of the spacer/emulator combo, unless, I suppose, you happen to need a massive amount of preload added.

High On Octane

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Re: Cartridge Emulator Installation
« Reply #10 on: January 01, 2015, 11:13:12 PM »
Do you think I will be ok with just the spacer on top of the damping tube?  My replacement fork springs were about 2.5" shorter than the originals anyway which is why I never installed them.
Scottie J  ~  Bulldog Kustoms Denver  ~  1958 Enfield/Indian Trailblazer  ~  1959 Enfield/Indian Chief

AgentX

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Re: Cartridge Emulator Installation
« Reply #11 on: January 02, 2015, 08:59:53 AM »
Apologies if this double-posts, but I thought I'd entered a response from my mobile and now I don't see it.

Best I see it, you could use the shorter springs by:

1) using a long spacer under the emulator; don't think this would cause issues with the emulator unless somehow it put the emulator above the oil level in the fork

2) using a shorter spacer under the emulator and another on top of the spring to take up any resulting slack

3) using a spring or spring/spacer combo underneath the damper rod as a lengthened top-out spring to shorten the overall fork  length, which might be desirable depending on geometry concerns.

Overall, unless you're running into coil bind with the shorter springs, you should be able to space it out to work.

cafeman

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Re: Cartridge Emulator Installation
« Reply #12 on: January 22, 2015, 07:54:28 PM »
Just received a response from MikeXS about the emulators they carry. They are 23.8mm diameter and 14mm tall. While they are smaller than the YSS mentioned above, they may still work with custom fab'd adapters. From whats been mentioned on various other vintage bike forums many have used them on larger forks than whats on the Enfield, with good results, and at $57 for a set seem worthy of considering. I'll be pulling the forks soon and verifying the dimensions to see if they are the same as what Agent posted, and what it will take to make 'em work. (unless somebody already has and would post!) Here's a link to a good thread by someone who dissected them basically: http://www.xs500forum.com/index.php?topic=240.0
« Last Edit: January 22, 2015, 08:05:50 PM by cafeman »
Current Fleet: 2001 Royal Enfield Bullet 500 Cafe Racer
                     1996 Yamaha Seca II
                     1991 Husqvarna 350WXE
                     1991 KTM 250MX
                     2004 Husqvarna TC450

cafeman

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Re: Cartridge Emulator Installation
« Reply #13 on: January 24, 2015, 07:47:03 PM »
OK, pulled a fork, disassembled and took measurements. This is on a 2001 500

Spring Free Length= 543mm/ 21.375"
     "       Outside Diameter= 28mm
     "        Inside Diameter= 18.5mm
Spring Stud Rebound Valve (picture #2): Diameter (springs sits on top of)= 28.5mm
                                         Inner Raised Tube Diameter= 18mm
Fork Tube Inner Diameter= 29+mm

Manual and various other sources calls for a 521mm/ 20.5" free length spring with a 1" diameter (based on various sources). It appears someone prior to  me fitted a longer spring w/ a heavier rate (I suspect this bike in its past life pulled a sidecar)
Regardless, the spring stud and fork tube dimensions should be consistent.  The 29mm YSS and 29mm Race Tech FEGV S3501 emulators will fit the later Enfields, and doing as Agent has mentioned/done should work no problems. But the MikesXS 23.8mm emulators will work also, as well as the various sized YSS/Race Tech emulators that are available (23.8mm/26.5mm) and the fork spring will rest on top of these sufficiently, only the required spacer would have to be stepped inside for the emulator to sit in and the outside diameter of the spacer could be up to approximately 29mm to match the spring stud rebound valve. Here's some pics of the components, the last picture shows measuring the length of the stud/valve in order to determine (subtracting the distance of the spring below the fork tube end) how much preload (in stock form) will be put on the spring when it is screwed into fork tube bottom.


« Last Edit: January 24, 2015, 08:02:19 PM by cafeman »
Current Fleet: 2001 Royal Enfield Bullet 500 Cafe Racer
                     1996 Yamaha Seca II
                     1991 Husqvarna 350WXE
                     1991 KTM 250MX
                     2004 Husqvarna TC450

cafeman

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Re: Cartridge Emulator Installation
« Reply #14 on: Today at 04:52:54 PM »
Got the MikesXS emulators, nice quality as expected, made adapters from gray 1/2" plumbing "couplers" from Lowes, which are 28mm diameter, have pipe stops (ledges) in the inside, perfect for the emulator to sit on, cut off 4mm from each end (down from 39mm to 31mm) one sides hole enlarged to a tick over 23.8mm for emulator to fit in, the other hole ends inner edge is chamfered to clear rebound valve head ports. All minimum inside clearances with emulator, spring, adapter and valve head are good.  Ready to install, emulators cost $63.39 shipped, and couplers were about .60 cents for both. Less than $65 and minimal time to make the adapters. Here are the measurements:

Adapter to fit MikesXS emulators (23.8mm):
             length= 31mm (4mm off each end )
            diameter=28mm
        emulator hole (one side only) diameter= 23.8+mm
                      hole depth to step= 14mm

 
« Last Edit: Today at 05:09:11 PM by cafeman »
Current Fleet: 2001 Royal Enfield Bullet 500 Cafe Racer
                     1996 Yamaha Seca II
                     1991 Husqvarna 350WXE
                     1991 KTM 250MX
                     2004 Husqvarna TC450