Debrix Emulators for FZS 600 forks

[kebab19]

 I recently returned to the FZS600 after being on the 1000 for four years. Upon return I was struck (literally) by the poor damping characteristics of both front & rear suspension. Admittedly, on a bike with 42k on the clock & no signs indicating that the forks had ever been off to enjoy an oil change, I should not have been surprised.

Nonetheless, being a serial suspension modder, I decided that it was one area of these bikes that can ( and should) be easily improved. I started with the rear, fitting an recent R6 shock & aftermarket dogbones. This provided superb results for around £150-180.
http://foc-u.co.uk/index.php/topic,8167.0.html

Now to concentrate on the front-end. I had a set of 5SL R6 forks in the garage from my Fazer 1000 conversion   
 http://fazer1000.yuku.com/reply/23677/Re-R6-forks-nonUSD-for-Gen1#.UcBnQdhq-MI      but the electronic speedo setup of the FZS600 is prohibitive & machining surfaces of fork legs ruled this conversion out from being cheap & easy. So, that left modding the standard forks. The common route of adding Hagon progressive fork springs & heavier oil masks the inadequacies of the damper-rod fork setup, but usually result in an overly harsh ride in order to regain handling.

As a few of you may be aware, I had previously modded a pair of FZS600 forks with Race Tech’s Gold valve Emulators, along with a set of linear-rate fork springs from a TRX850:   
http://foc-u.co.uk/index.php/topic,71.0.html   
No point going into detail regarding the benefits of emulators here, there's plenty of info out there on the web regarding technical details.  Anyway....although the experiment was successful, unfortunately it was relatively expensive. Furthermore, from what I have gathered, there were four aspects that limited the mod’s potential in people's minds.

CONCERN
1)      The Race Tech (RT)  Gold Valves were expensive (£150)
2)      The appropriate linear-rate springs were expensive (£75-90)
3)       Fork surgery was necessary & drilling holes weakened the damper rods
4)       The mod was permanent

SOLUTIONS
1)      Since my fork mod I have noted that others have found a viable, cheap alternative to Race Tech’s product – emulators from Debrix: http://www.debrix.com/41mm-Fork-Damper-Valve-2000-up-Harley-FXST-Softail-p/24-0361-vt.htm    .Cynics rightly point out that they are cheap Taiwanese knock-offs that lack instructions and are made for Harley Davidson forks. However, some SV650 riders have fitted them, followed Race-Tech’s instructions and were surprised to find that when setup properly they worked just as well     http://www.svrider.com/forum/showthread.php?t=112643    . These Emulators / emus cost about £30 instead of RT’s £150.
2)      Although RT rightly point out that linear-rate springs work best with their emulators, a wide variety of hard-up riders (from Suzuki Burgman  http://burgmanusa.com/bkb/650+Race+Tech+Installation   to Kawa KLR 650  http://www.advrider.com/forums/showthread.php?t=126358    have run these emulators successfully with progressive rate springs fitted, usually the standard spring setup for budget bike forks. This means that the Debrix emu setup would still work very well with springs from Hagon, Wilbers or even the standard FZS fork springs. I’m currently running standard, progressive springs from a Honda VFR750 and it still works very well.  Admittedly, the FZS springs are too soft for the average sized European rider & an option here would be to shorten the fork springs, making the springs firmer, but that will be info for another thread....
3)      As per RT emus, it’s still necessary to drill out the compression holes in the fork damper rods.  Do a search on Google for failed damper rods after doing this mod right – I couldnt find any so I assume it's an absolute non-issue if done correctly.  I have realised, however, that the size of the holes do not have to be as large as I originally recommended. I have modded mine with variable-sized holes & the setup appears to be working just as well. Of additional interest is that the Debrix emus fit STRAIGHT on top of the FZS600’s damper rods, meaning that widening them with cutting stones (as per my original Gold Valve instructions) is no longer necessary.
4)      The mod is still permanent. Permanently better suspension, how awful! Still, at least this time round the cost of parts for modification is more like £50 instead of £250, so you won’t lose much should you sell the bike on.
 
Having fitted & used this modded suspension in anger, I can wholeheartedly vouch for these Debrix emulators as a very cheap & effective alternative to RT’s Gold Valves. I probably sound like I’m on commission from them, but again just thought that spreading this info might encourage some FZS owners to proactively improve their forks immeasurably. The main problem with the emus is the cost of postage from the US, effectively doubling it, but I noted that the SV650 owners resorted to group buys in order to minimise postage costs  http://forums.sv650.org/showthread.php?t=174548  http://forums.sv650.org/showthread.php?t=175607   . Indeed, I picked up my Debrix Emulators from one of them! This 'Group Buy' approach would undoubtedly also be the cheapest way for FZS owners to get these emus, but only if there is sufficient interest in such fork modding...... 

If there is enough demand, I will do another Debrix emulator installation thread with relevant pics, modifying it where necessary.

 

[Motorbreath]

It's very interesting. I had already read your racetech thread. You are really a "cereal" modder. I have no place to work on my bike now but it could be done a in a few months.

I cannot be part of the group buy as I am from Spain though.

I bought a pair of 1kg/mm linear springs at http://www.bmsuspension.com/index.php/en. 79€ incl. shipping.
SAE 20 oil -warmer weather here- and less preload (I have a shorter spacer). When preload adjuster at the lower setting the total preload is 0, as latest trend on track and motocross forks.

It is firm and fantastic at braking but not the most confortable when pavement is bad.

I am curious about your R6 rear. ¿What is the spring value?

Edit: I realize shipping from USA is so expensive it seems that it would be cheaper to participate in a UK buy group and then have it posted from UK to Spain.

[kebab19]

Hi,
Your forks are an example of gaining more control at the expense of comfort. With the basic damper rod fork design of Fazers / Hornets / Bandits / budget bikes in general, there is no way to improve fork performance in all areas without something being compromised. Compression characteristics seem particularly bad, the area in which these emulators work best.
The good news is that in the future your forks are ideal for this sort of conversion, as is anyone with aftermarket springs and heavier fork oil fitted already. Fazers with standard springs could also be modded to improve their damping function, but I suspect the gains might not be as great.

The R6 spring is the standard unit that comes with the shock (couldn't see any numbers etched on the spring).  I set the spring's preload to MAX as it's for a bike some 25kg lighter. Having said that, I might take the preload back down a notch or two in order to gain even more comfort, I was mildly concerned it might bottom out, but all is well ;-)

Regarding a future group buy of emulators, I'd much prefer to have a couple of other Fazer owners try out the emulator conversion first to confirm my findings before trying to organise that sort of thing.   

[Punkstig]

Good find, well done, and thanks for trying it yourself and showing your results!

[wezdavo]

I am very interested in this...
 
Even if there is no group buy I am tempted to just get a set, with post works out around £55

[wezdavo]

So the upper rebound hole is left as is and the lower compression holes are enlarged to defeat there dampening effect?
 
The valve is allowing adjustable compression dampening and the rebound is being controlled by oil weight?
 
And the valve seats properly in the damper rod?
 
Is the low speed compression effective?
 
I'm getting exited

[wezdavo]

So the upper rebound hole is left as is and the lower compression holes are enlarged and added to to defeat there dampening effect?
 
The valve is allowing adjustable compression dampening and the rebound is being controlled by oil weight?
 
And the valve seats properly in the damper rod?
 
Is the low speed compression effective?
 
I'm getting exited

[kebab19]

Wezdavo, Answers to your Qs as follows:
 Rebound Q - bit of debate on this one, discussed at length by the SV650 crowd. Some say to weld / braze / Araldite the hole, others suggest leaving it as it is. I've not blocked mine up, thought I could fill it at a later date for comparison. Compression Q - yes, you destroy the existing circuit in the damper rod & let the emulator dictate compression. This is done by adjusting the preload on the spring. RT suggest from between 2 full turns and a max of 4 for road use / trackdays. Debrix emus come with 5 turns preload, but they are setup for half-ton Harleys...
 
 
 
 Yes, rebound by oil weight hence the recommendation of switching to a heavier oil such as 15w or even 20w. I used Yamalube 15w. Oil height within the fork is another factor to consider, as the standard fluid height is affected by the presence of the emus. This change in height also affects fork travel.
 
 
 Perfect fit, couldnt believe it when compared to my old RT emulator mod which involved the tedious process of removing damper rod material to make them fit.
 

 I've only had them in place for a few days but notice a vast difference in the compression characteristics. I'd estimate that some more fine-tuning may be required (as I'm a bit of a perfectionist), but compared to the original damping characteristics, like night & day already. Going 110mph over potholes (on a private road) led to more grief from the back-end than the front, so I guess that would be a 'yes'
 
 
 Excellent, although the drudgery of drilling holes etc might curb your enthusiasm a bit 
 

[Jamieg285]

I'm someone who hasn't got a clue about damping, whether my current setup is knackered or not, and what difference in feel these changes would make.  I am however, all for making improvements, and for the costs quoted I'm certainly interested.


Should the front and rear be done at the same time?  If not, which end is the better one to start with?

[kebab19]

Jamie,

The best way of thinking of damping is:
'When I ride over this bump / rut / pothole, does my suspension absorb the impact or does it pass it on to me up through the bars / seat? If there is jarring motion from either / both ends then it's fair to say your suspension damping isn't quite doing it's job. With the Fazer's standard forks & rear shock there is fairly minimal adjustment / tuning you can make to either end to eliminate this problem.
 If however you go over the road irregularity & there is minimal disturbance transferred up to you then the suspension setup is doing a much better job.
Compression damping is the forks / shock compressing as the impact pushes the wheels upwards. Rebound damping is the forks / swingarm extending & returning the wheels back down. You want both movements in a controlled manner, but with damper rod forks only partially successful.
There are further complications, such as high and low speed compression & some rear suspension characteristics affecting the front, but you get the basic idea.
This might help u understand the basics of suspension (or make things more confusing!)    http://www.wpsuspension.co.uk/setup.php 

I started by changing the rear as I already had the shock from my FZS 1000 days, but improving one end will definitely highlight the inadequacies of the other end. You could hunt down an appropriate R6 shock (currently on ebay : Item number: 121128085249, Item number: 180988631654, Item number: 111015636838) but aftermarket dogbones are needed & will raise the overall costs. Failing that, you could get get a Fazer 1000 shock & then stick the 600's spring on it. Providing the shock isnt shagged & needs a rebuild, either option will be much better than the standard Fzs 600 rear shock. This is because they also have adjustable compression and rebound adjustments built into them.

Front end....wait & see whether there is enough interest / demand for a group buy, although IMO £50 is still fairly cheap to cure front-end compression woes. I might start doing the fork conversion for any people interested if it's beyond their abilities or the tools they have available. Would really like some others to try it first tho, as I don't wanna come across as some sorta snake-oil salesman for something no-one has yet tried...

[ponkster]

Do you still drill extra compession 'vent' holes with this emulator or will enlarging the existing two to 8mm be enough?
 
Also is the emulator pre load measured in full turns (tightening the spring) from when the treaded alenkey bolt is flush with the bottom of the nut on the underside of the emulator?

[kebab19]

Do you mean the holes in the damper rod? Going by the SV650 forums / threads / guides etc, there is considerable debate as to whether enlarging the existing holes is enough or whether extra holes are required. Racetech themselves claim that you MUST drill extra holes - for example, someone on this link has provided RT's instructions (point number '3').  http://hawkgtforum.com/forum/showthread.php?t=1355
Others have argued that making a total of six holes is excessive and argue either for fewer holes (such as four in total, often 10mm wide) or just widening the existing holes only. AFAIK some of this particular debate is in relation to using the emulators for racing purposes, where they are very popular.

From our point of view, it might be a case of trying to widen the existing holes to 8mm, but if the standard compression still works you'll have to take it all apart & redrill the rods again. I went with six holes but different sizes as they went up the damper rod - bottom two holes 8.5mm, next two 8mm and top two holes 6mm. Another alternative may be to try only four 8mm holes, but i'm no liquid flow expert, so can't be certain what minimum area of damper rod material needs to be removed in order to kill off the standard compression damping.

The allen bolt through the emulator is threaded at the bottom, as it didn't fly apart when I removed the bottom nut! To set preload on the emulator, take the bottom nut completely off, then loosen the allen bolt until it barely touches the washer / spring.
Then rotate the allen bolt to give preload between 2 to 4 full turns. The SV650 mob suggest 2.5 turns so I went with that. 3 might be better if you are....big boned. 4 turns would be more suited for the racetrack environment. 5 turns needed if you're on a Harley, apparently.  Once you have set preload, hold the allen bolt steady in postion, put the bottom nut back on & tighten her up. Dont allow the top allen bolt to start moving once the bottom nut nips up as I think it's one of those nyloc jobbies.

[Motorbreath]

The question is: there is enough room for drilling more holes without having them turned into big rebound holes when the suspension is at full travel?

I mean, would the new orifices still remain into the A zone when the fork tubes dive to the bottom?


If new holes enter in B zone it would left us without rebound damping and would increase the compression damping when breaking very hard. In any case holes should be drilled as low as possible. Or just enlarge the existing ones.

[kebab19]

The info below was lifted from the very good Suzuki Burgman 650 Race Tech Installation link mentioned in my original post above:

 "Step 5 Drilling The Holes Out In The Damping Rods A bit of mixed information on this in the posts. Here's what I found.
 
 Damping Rod ID 0.732" (18.6mm)
Damping Rod Opening Area 0.421" (10.69mm)
 
 Existing Hole(s) 0.236" (6mm)
Existing Hole(s) Opening Area 0.044" (1.12mm)
 
 By my calculations:
 
 The inner diameter of the tube is 0.732" (18.59mm) which has a flow area of 0.421" (10.69mm)  100%
A 0.236" (6mm) hole has a flow area of 0.044" (1.12mm) Multiplied by 4 holes is 0.176" (4.47mm) 41%
 
 Known Choices: A 0.313" (7.95mm) 5/16th hole has a flow area of 0.077" (1.96mm). Multiplied by 6 holes is 0.462" (11.74mm) 109% Exceeding the flow area of the rod.
 A 0.354" (9mm ) hole has a flow area of ~0.098" (2.9mm) Multiplied by 4 holes is 0.392" (9.96mm) 93% Slightly restricting the flow through the rod.
 A 0.375" (~ 9.5mm) 3/8th hole has a flow area of 0.110" (2.79mm). Multiplied by 4 holes is 0.440" (11.18mm) 105% Exceeding the flow area of the rod.
 
 I used a 0.375" (~ 9.5mm) 3/8th drill and enlarged the 4 existing holes. You'll need to choose what your comfortable with and works best for you.
After talking with Kiwi Dave about the ever so slight restriction using 9mm holes, he received this response from Crown Kiwi Technical Ltd, the ones who recommended the 9mm holes:
 
 "We had never worked out the flow area as such but irrespective the increase in hole size somewhat desrestricts the maximum allowable flow before it will "choke off" when riding over the most abrupt bumps. If the hole size can be increased further without weakening the integrity of the damper rod in that area then go for it. Adding further holes further and further up the damper rod is BAD as it takes away more and more travel where there will be little or no rebound damping."
 
 Now I'm certainly not a fluid dynamics specialist, so to be fair, it's possible that the maximum flow through the emulator body is less than the Damping Rod to begin with and the slight restriction of the 9mm holes is irrelevant. Heck, we might even be able to go smaller. The integrity of the Damping Rod with the larger holes does not seem to be an issue reported by anyone. Luckily for me as mentioned at the start, I'm just compiling and presenting this information, you get to decide what you do yourself."

From that, the answer is not definitive, but IMO does suggest larger holes as low as possible, but without affecting the structural integrity of the damper rods. If you're prepared to take the forks apart a few times, try enlarging the two existing holes to either 8.5mm or 9mm. If this doesn't prove to be enough, drill a further two holes higher up the rod either 7.5mm or 8mm in diameter.

I went with TRX850 fork instructions, which are in a pesky .MHT file & am not sure how to upload it to photobucket or similar for everyone to peruse. Those forks are quite similar to the Fazer's forks bar their length. Nonetheless, it recommends drilling a total a six 8mm holes for TRX damper rods, which I copied in my original Gold Valve mod but reduced their size for my Debrix mod. The two uppermost holes on mine don't *seem* to have affected my damping for the worse.

[Motorbreath]

It seems that Fazer rods have less room than those. It would be useful that somebody could measure them from the top lip to the compression holes. When riding hard our feelings are often incomplete. For example I cannot tell the difference between hydro-lock and bottoming.

The ancient GSXR I rode yesterday made me remind how bad our forks are 

[Val]

Hi guys,

I know this is an old thread. IMO it should have been moved to articles section say "FZS 600 front suspension upgrade".

Some of you probably know that, but Debrix are just a seller for the cheap 41mm emulators produced for Harleys that fit SV650 that fit our FZS 600: http://www.svrider.com/forum/showthread.php?t=282921

Following the SV650 link I just bought for £60 two emulators:

http://www.motoparthub.com/24_0361_VTwin_41mm_Fork_Damper_Valve

Here we come my winter front suspension upgrade.

Have not decided on the springs yet any ideas are welcome 

[kebab19]

Hi Val,
Use the chart linked below to work out what spring rate suit you best (you'll want the 'Sport' red line unless you're only doing trackdays & racing). Bike is about 465lbs wet weight unless Yamaha are spoofing, just combine that with your own body weight. 

http://www.mad-ducati.com/Technical/racetech/SpringChart.html 

For single rate springs, K-Tech do them at various increments for the SV650 and it's just a case of trimming the inner metal spacers to suit both spring length and emulator height.
Alternitively, I've had great success with Honda VFR750 / early VFR800 springs which occasionally appear on ebay.
Also try & source some fork cap preload adjusters if you don't have any on your existing forks.

[midden]

It seems that Fazer rods have less room than those. It would be useful that somebody could measure them from the top lip to the compression holes.

141.5mm compression hole to lip
115mm  between compression and rebound hole

[Freza]

Sorry for reviving this old topic, but I've been looking everywhere to buy these Debrix emulators and can't seem to find them.
If anyone has any info, it'd be appreciated.
Thanks

[kebab19]

Funny enough this topic seems to be coming back, I was considering another Group buy from the States if there was enough interest.

You can still order them from several sources, such as this one;
http://www.biker-direct.com/front-fork/fork-tube/fork-damper-tubes?sort=20a&page=2&zenid=10c2d9df29a6c8d654e05010f74d37e3

However, the Sterling exchange value and Import tax will probably make them about £65 now  still worth it tho ...IMO 

[Freza]

Shipping to my country is $65, more than the emulator 
Converted to GBP, altogether it'd cost me £85 ($110). Thanks but no thanks, since I can order original Race Techs from Ebay for $128 (free shipping), so it makes no sense.


However, I'm now trying to find harder linear fork springs (at least 8 N/mm) to work together with the emulator...

[midden]

No pleasing some people 

[tommyardin]

Shipping to my country is $65, more than the emulator 
Converted to GBP, altogether it'd cost me £85 ($110). Thanks but no thanks, since I can order original Race Techs from Ebay for $128 (free shipping), so it makes no sense.


However, I'm now trying to find harder linear fork springs (at least 8 N/mm) to work together with the emulator...

Same as that to the UK, a few cents less than 110$ with shipping. eBay has the Race Tech gold emus for not a lot more, I might go that route also. Have enjoyed and been enlightened by all of Kababs posts on this subject.

[Freza]

Of course, I wouldn't be thinking of emulators if it wasn't for kebab19

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[tommyardin]

Of course, I wouldn't be thinking of emulators if it wasn't for kebab19

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Yeah! He has a lot to answer for