Fork Valve Turbulence Reducing Modification

[R_Cote]

Modified Valve Porting

While I'm waiting for my Race Tech springs to arrive, I been researching this valving stuff a bit more. Ive decided to open up the compression ports on my pistons. Right now I can't pop the doe ($$$$) for the gold valves. Nor do I want to. I want to see what I can get out of the stock components. I can't see any major drawbacks by opening up these ports just a bit. They measure 1.72mm in stock trim and I'm going to open them up to 1.9mm each. This will give a bit more flow for better compliance, I think anyways. Can't see where it will harm anything.

My question is, has anyone around here ever tried this and if so what was the outcome?

I will try to post some pics of my brain sugury when I get it done.

P.S.

I especially liked the Peter verdone desisigns website where he speaks of the HMAS ( Honda Multi Action Suspension ) valves.

Thanks joe for steering me there.

Arrow points to one hole thats drilled larger. Went form .069" to .077" Dia.

Piston

Comparison of all 4 holes drilled in piston on the right.

Drilled comparison.JPG

Backside of compression piston ports chamfered to supposedly reduce turbulance.

chamfered backside.JPG

Finished product.

Final piston mods.JPG

[Trace]

And the results are.........?

What voodoo and magic did you use to come up with your drilling sizes? Did you mod any of the OEM shim stack? Did you use OEM weight oil?

I'm planning on installing the full Racetech setup, so just curious of your outcome.

[Guest 767fixer]

trace has a point....what is the outcome? did you ruin your suspension? this is like telling someone to pour vinegar in their radiators, but give no reason why?

[Trace]

I'm gonna go pour vinegar on my radiator right now...I don't even CARE why! :lol:

This fork stuff is REAL important...it's a mix of science (99%) and the experience to understand and thus apply the science.

The RaceTech setup has been known to be a little too stiff unless you're tracking the bike....but that can be the result of an overzealous buyer who actually thinks he'll be tracking his viffer a whole bunch and has a chance of keeping up with the fast, light, powerful stuff. Instead, he spends all his time on the street (like everybody else) and think's it's too harsh.

I'm planning on the .90 spring (much lighter than what guys "normally" are going with), and the softer valve shim stacks. [i'm adding F3 fork-guts to get rebound control]. I figger anything is better than the mushy OEM setup, but I DON'T want to 1) ruin the characteristics of the bike or 2) try to second guess all the experts who either designed the bike or actually know what they're doing....unlike myself!

[HispanicSlammer]

You must understand that porting the relief holes does nothing to the valve shims or change the characteristics of the compression or rebound valving. Those holes that were ported are the escape hole for the oil once the compression stroke is finished and in the case of a compression valved the fork is on the rebound stroke and so the fork oil is moving in the opposite direction.

There is a lightly spring loaded heavy shim on the top of the valve that only allows oil to travel in one direction - its called the "Top Hat" or a "Check Valve" it opens on the rebound stroke and allows oil to move in the opposite direction to allow the cartridge to fill up with oil again. It is the holes that flow the oil back into the cartridge chamber. these are the holes he has ported here, regularly they are just drilled strait and so there is a mad rush of oil into those 4 little holes and some of it gets caught up in turbulence and reduces the effectiveness of the rebound damper piston. What he is doing is opening the exit doors wider to allow the oil out easier

border='0' alt='user posted image' />

In this figure the port is the channel the bypasses the shim stack on the bottom and is capped off with the check plate. In actuality they are between the intake ports and are recessed a bit from the shim stack to allow oil to flow backward on the rebound stroke.

He has also ported the intake holes a bit too but they still have to flow through the same sized hole toward the middle of the valve so they still have the same flow restriction due to the size of the compression holes.

[ULEWZ]

It's interesting that this post is pinned, and it hasn't even had a ride review yet, so please, post a review.

[Trace]

It's interesting that this post is pinned, and it hasn't even had a ride review yet, so please, post a review.

<{POST_SNAPBACK}>

Yaaaa...I was gonna badmouth the whole thing (in spite of HS's clarifying explanation as to what is going on with the mod), because nothing is going on! But, I figger that if you can't say something nice or encouraging.....you might as well go pour vinegar on your radiators....... :wheel:

And if I can read between the lines of HS's explanation...we're prolly not gonna get a definitive ride review, because this mod doesn't really DO anything. The enlarged ports could help prevent foaming/cavitation or other unruly oil behavior under extreme conditions, but I suspect there is no "feel" change for 99.9% of riding. JMHO, but that's why I asked what else was done. I can't imagine taking all that oily, slimey stuff apart just to port those valves, but if that's the case....what's up with it?

Heading for my rads with bottle of vinegar in hand........and I just did order springs [settled on .95s], comp & rebound valves and and other upgrade goodies from Racetech (except their $25/quart 5w "snakefork" oil...sheeeesh!!) All in stock, should be here in 5 days. Incidentally, they do honor the 15% discount for VFRd members---which saved me $75! :thumbsup:

[enzed_viffer]

which port does the fluid go through during compression?

<{POST_SNAPBACK}>

I think it goes through Singapore. :goofy:

[Baileyrock]

It has to effect fluid dynamics in the forks, look at Race tech Gold Valves, you could pour a Volvo through their ports. Ohlins are much smaller, closer to the HMAS(honda) valves, but have a little larger ports like what he's doing here.

I think most people here including me don't have a clue what's going on in the forks! :goofy:

[Baileyrock]

which port does the fluid go through during compression?

It goes through four of the port holes in one direction and back through the other four going the opposite direction, plus any other bleed holes or whatever. :goofy:

[Trace]

Just FYI, I decided to go with the .95 springs also (I was leaning towards the .90s), but I'll build slightly "softer" comp and rebound valves than what RaceTech typically recommends for the standard street setup.

I've reached this setup configuration after 1) reading numerous posts about harsh results from many of the aftermarket vendors [YMMV], 2) from understanding that the stock VFR is under sprung and over damped [so I'm going the other way!], and 3) taking some advice from HS regarding his trial & error discoveries. Many of you have gotten good results by sending your stuff away for upgrading, but many more have been less that happy with the "welded fork" ride.

I also bought their bushings and seals, which are only slightly more expensive than ePay and other internet parts houses, because of the convenience factor and the quality of the bushings. Don't know what your getting from all the ePay vendors....standard OEM, or not as good as OEM, perhaps? Dunno, but don't wanna risk it.

I will use 5W oil as recommended, but not Racetech's outrageously expensive stuff. The local CycleGear ripoff-shack sells perfectly good oil for $8/quart.

[Trace]

It goes through four of the port holes in one direction and back through the other four going the opposite direction, plus any other bleed holes or whatever. :goofy:

<{POST_SNAPBACK}>

Yeah, and there's simply no way to know if that reaming of the ports did anything positive or negative. I certainly doubt there are any negatives, but I'm somewhat skeptical of the positives. And to be fair, that's exactly what R-Cote said when he posted his mod. He's experimenting, knows it's not like a full re-valve, and wanted to improve what he had. But......who wants to go thru all that trouble (and potentially bugger the stock valve somehow!) for unknowable improvement?

So......... :lurk:

[Baileyrock]

And the results are.........?

What voodoo and magic did you use to come up with your drilling sizes?? Did you mod any of the OEM shim stack?? Did you use OEM weight oil?

I'm planning on installing the full Racetech setup, so just curious of your outcome.

What several Suspension Geru's (like Phil AS) have told me that the Gold Valve ports are so big that they no longer perform one of the functions there are designed to do and that adds one more thing for the shim stack to control. The more areas the shim stacks have to control, the less effective they do it.

Many tuners will NOT use Gold Valves period, not that they can't improve the stock forks performance. These tuners and major suspension co. like Ohlins do not agree with this HUGE port method of controlling the forks action.

just what I here ! :P

[Trace]

What several Suspension Geru's (like Phil AS) have told me that the Gold Valve ports are so big that they no longer perform one of the functions there are designed to do...

<{POST_SNAPBACK}>

BR,

I can see that POV, especially from a highly skilled and experienced suspension guy who knows how to tailor the mechanism to a very fine degree of control for a given situation.

But I also see how the shims in the Racetech stuff can act to control flow in lieu of the more traditional orifice size. That's why they're so big/tall compared to stock stuff. In general, it seems to work for most average riders (like me).

What I REALLY think is the case is that Racetech has found a market niche that allows "tunability" for the non-expert (like me) while greatly increasing performance over OEM stuff. They manage to do this with only relatively few products, having just a few valve sizes and lots of shim stacks "do the work" for a very large number of bikes and conditions. Brilliant! But I can also see how this Exotica For The Masses would get an unfavorable response from the real pros like Phil, etc. The experts work both ends of the equation....tuned orfice sizes, tuned shim stacks. Racetech only works one end...the marketable end. Voila!!

I liken it to this: You can go to any speed shop and afford to buy roller rockers for your small-block Chevy, and they're MUCH better than factory stamped steel units. Now you're feeling pretty racy, huh, now that you have Exotica For The Masses? Or....you could go to Jessel http://www.jeselonline.com/ and spend about a billlllliiion dollars and get a REAL roller rocker valvetrain that you have absolutely no real need for with your stock engine! :salesman: Same thing applies to musical instruments, stereo equipment, kitchen knives.....anything. Marketing and pricing step-functions affect all consumers.

How fast to you want to go? How much money you got?? :goofy:

[Trace]

GP suspension lost me when they said there was no need for race tech valves then in the next breath proceeded to try and sell their version of valves and "compression needles" :goofy:

<{POST_SNAPBACK}>

Sure! One pro scoffs at another's stuff. I'm sure a real Team race bike guy scoffs at ANY vendor of stuff. An exactly similar situation exists in the rarified world of NHRA Pro Stock 500 cubic inch engine builders....all 20 or so of the successful ones. They scoff at Jesel stuff!!! Everything they use is virtually hand built....they don't have much use for speed shop stuff, either. :P

Wot the heck is a compression needle? Will you have adjustable compression damping because of it? If so, wow!!

[HispanicSlammer]

There are two schools of thought on the size of the holes and the thickness of the shim stack. Race tech beleives in a large port and then thick shims stacked in various stacks to control the flow of oil and tailor the damping. While others use smaller holes like Ohlins thinner shim stacks to tailor the damping. Yamaha had such small holes on thier initial set of r1 forks that the shim stack was virtually moot cause the darned holes were so small that the oil could not get through - most r1 racers pitched thier forks for better ones, cause they were awful. They have rectified that, FZ1 had the same issues with the forks.

Ohlins valve holes are still bigger than Showa though, the race tech valves are almost twice the size. I subscribe to the school that says let the shim stack control the flow, I think that is partially why Ohlins builds huge oil resevoiurs into thier dampers cause flowing then through small holes heats up the oil faster, so they need lots of it to regulate the temperature. My Ohlins is supposed to be consistant under temperature changes.

One school says let the shim stack control the damping

the other says let the valves holes do most the work.

[Guest 767fixer]

One school says let the shim stack control the damping

the other says let the valves holes do most the work.

<{POST_SNAPBACK}>

all my school ever taught me was reading and arithmetic....i feel jipped

[Trace]

There are two schools of thought on the size of the holes and the thickness of the shim stack.? One school says let the shim stack control the damping the other says let the valves holes do most the work.

<{POST_SNAPBACK}>

Agreed. Regardless of which school is "more right", it's clear that it's really hard to adjust a hole smaller once you've drilled it out! The pros have a whole tackle box full of comp and rebound pistons, with all sorts of different holes, shim configurations, etc, etc, so they're not drilling valves at the damn track!!! What Racetech has done is give you a valve that works much better than stock, and has lots of adjustability.....5 settings on either side of "standard". I think it's a very workable compromise between OEM and "$pecial cu$tom $tuff".

Ohlins is the acknowledged King of this game, with $$$$ to match. I don't need that kind of specialization 'cuz I can't ride for crap. <_<

And I see that R Cote was here while I was typing this.....but no comment... :goofy:

[ULEWZ]

There are other alternatives to Race Tech gold valves. All these are suppose to work better and last longer:

Ohlins Cartridges (Dan Kyle sells them)

Axxion Cartridges (Traxxion Dynamics sells them)

GP Cartridges (GP suspension sells them)

[R_Cote]

Wow! Holy Crap. You guys are featuring me now. I thought it was funny. When I originally posted this as " Valve Modification, any luck? I didn?t even get 1 reply.

I can't be the first goof ball to try this. What the heck it was winter time, I wanted to pull it all apart and inspect everything, and change the fork oil. One thing led to another. I did the normal research and agreed that the viffer was undersprung. Thank you very much H.S.

Now I know I made too many changes at once, including a new Metler z6 up front . I?m impatient like that. But I can tell you it wasn?t a bad thing. It?s actually a lot better. I guess that means the stock setup realy did suck.

So in order to make a long story short. I went with:

1.0 Race Tech Springs

77mm spacer ( cut from tube included in spring kit )

5wt Silkolene Pro RSF

Oil level @ 140mm

Rider Sag set to 32-33mm in front

Below, I copied and pasted this from a previous post, to baileyrock, about this same discussion. I guess some of you missed it. So here it is.

Quote:

Where did you get the valves? I may be interested. By the way I finally got mine all back together and got a chance to ride it for 35 miles. It is a good improvement over stock. I attribute it mostly to the proper strait rate springs I installed. (Race tech 1.0's )

The ride is much firmer but not harsh. Also the annoying brake diving is all gone. The front end just feels more planted. I rode some bumpy roads and hit some good size frost heaves and big dips in the road and it wasn't at all twitchy. No back and forth bar movement at all.I like it.

when I finished the short ride I checked how much travel was used up and found it still had 1" left that did not get used. This is also with a lower than stock oil height I believe. I set the oil level at 140mm. I think the manual only states to measure out a certain amount and fill it. Not sure if I should try 145-150mm (less oil more air) on the oil height. I'll have to ride it more and harder before I make any more changes.

Another thing that impressed me was it also eliminated the nagging bar jerk that was always associated with making a very slow ninety degree turn on an offcamber. Like pulling into my driveway there is a sort of step up speed bump, so to speak. Actually it's part of the old curb before I had my driveway paved, and my driveway is higher than the street. This always yanked the bars pretty hard and I had to be careful. This seems to be all gone. I tried it like 4 times and could'nt duplicate the problem. It made me laugh. Like I won a battle or something.

I'd also like to add that with these springs I had cut the spacers to 70mm which gives me minimal preload with the adjuster almost backed out all the way.

So far I'm loving this set up. But It's only been 35 miles.

End Quote.

I've since put on almost 2 hundred miles on my new set up and still like it. However I'm starting to pick it apart. The ride is definitly no longer harsh but it is firm. Maybe a bit lighter spring rate would be better but I went with the race tech chart for my weight. I've been riding it more aggressivly and it is much more confidence inspiring. No surprises yet, except I did get pulled over for speeding. There's a first for everything.

The next adjustment I would like to try is to lower the oil level. I would like to see that last inch of travel get almost used up. I'n still trying to anylize in my head what the suspenion is doing and where it is lacking. If anything I think I should have gone stiffer on the rebound stack. I'm not quit sure but I think it's borderline bouncy on the slow shaft speeds. You know, the under 30 MPH small consecutive bumps. A few more miles should help figure what the adjustment will be.

Thanks for listening.

[R_Cote]

And the results are.........?

What voodoo and magic did you use to come up with your drilling sizes?  Did you mod any of the OEM shim stack?  Did you use OEM weight oil?

I'm planning on installing the full Racetech setup, so just curious of your outcome.

<{POST_SNAPBACK}>

Don't think it's Voo doo Trace. Actually the drilling size I got from this site. Be prepared to get lost if you visit this site. Lots of good Suspension geeks there.

http://www.activeboard.com/forum.spark?for...7705&topicPage=

Yes I did mod the shim stack. If you like I can post what stock was and what changes I made.

I used 5wt Silkolens Pro RSF.

[R_Cote]

trace has a point....what is the outcome?  did you ruin your suspension?  this is like telling someone to pour vinegar in their radiators, but give no reason why?

<{POST_SNAPBACK}>

AHH! Vinegar. There's an Idea. Do you think it will give a plush ride or will it be too harsh?

LOL!

[Trace]

Yes I did mod the shim stack. If you like I can post what stock was and what changes I made.

<{POST_SNAPBACK}>

Cote,

I'm sure many of us (as evidenced by the interest this post began to stir up once I asked "results??") would be interested to know your mods and your results.

As for voodoo, that's a generic term for any of this stuff than blends science, experience, results, yet it can't really be "seen" working. Until you can confirm that something works (and why!!) it's still voodoo. :P Cylinder head flow=voodoo. Fork & shock oil flow=voodoo. Computer programming=voodoo. :goofy:

Once everyone digests your long post, above, be prepared for lots 'o questions!!

I noticed that you're a little unhappy with your 1.0 spring, which confirms my decision to go with a .95. Mebbe a .90 would be right, but I'm 200 and DON'T have a pothole-y environment, so after staring at the chart for an hour and working the little calculator a dozen different ways (voodoo!!) I settled for the .95. So, what's your take on the 1.0, in detail.

Also, why the 140mm oil level? That's 10mm low (?), as I recall. Did you mix vinegar with the fork oil?

[R_Cote]

Cote,

I'm sure many of us (as evidenced by the interest this post began to stir up once I asked "results??") would be interested to know your mods and your results.

As for voodoo, that's a generic term for any of this stuff than blends science, experience, results, , yet can't really be "seen".  Until you can confirm that something works (and why!!) it's still voodoo.  :P  Cylinder head flow=voodoo.  Fork & shock oil flow=voodoo.  Computer programming=voodoo.  :goofy:

Once everyone digests your long post, above, be prepared for lots 'o questions!!

I noticed that you're a little unhappy with your 1.0 spring, which confirms my decision to go with a .95.  Mebbe a .90 would be right, but I'm 200 and DON'T have a pothole-y environment, so after staring at the chart for an hour and working the little calculator a dozen different ways (voodoo!!) I settled for the .95.  So, what's your take on the 1.0, in detail.

Also, why the 140mm oil level?  That's 10mm low (?), as I recall.  Did you mix vinegar with the fork oil?

<{POST_SNAPBACK}>

Not exactly sure that I'm unhappy with the 1.0's. The ride is firmer but not annoyingly firm. I installed the springs with the spacer cut to allow mininal ( 5mm ) of preload with the adjuster backed out all the way to the last line. I still had to turn the adjuster in aproximatly 12 mm to get to 32-33 mm sag with my 170lbs. When you get your springs consider using a longer spacer, assuming the spring is a bit lighter than mine and your body weight is higher.

I went with 140mm because I forgot to measure what it was before I dumped it out. I assumed the manual would give a measurement but it only says to put a certain volume in. OOPS. I read somewhere about how you want as little a level to control bottoming. There was a specific way to do that by filling the fork up while in the compessed state and the damper rod pushed all the way down and filling with oil to about an inch above the cartridge. I felt this to be a little too low as I know it wasn't that low to begin with. I settled on 140mm. Go figure. I would like to know what level people are running in these forks. I may still lower it to 145mm to try to use more travel up.

[Trace]

The OEM oil setting is 130mm. The standard thinking is if you have too much spring, reduce the oil (like 130mm+ height). If you want "more spring", you add a little oil (less than 130mm height). Of course, there must be some solid upper and lower limits to this, like + or - 10mm or so? Dunno.

So mebbe your 140 is fine with your 1.0 spring @ 170 lbs. I will prolly go to 128 or so, to reduce the air volume and thus add a little more "spring". Like I said.....it's all voodoo!! :goofy:

I recall where HS had to re-cut his spacer (shorter) to get enough sag because it was too LONG the first time, yet you say to make it shorter than the recommendation. More voodoo! But good advice on your spacer length issue, thanks. Too bad we have to diss-and-reassemble the whole thing to see where the sag will ultimately be.