Fork revalve, modifing with stock parts
04-21-2005, 08:10 PM
#1
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Fork revalve, modifing with stock parts
[quote="VTRBeefa";p="4634"]You find a very good suspension mech : )
I was going to get the gold valves and this is what he told me.
He has a fair amount of cred in the industry so knows his stuff. Also used to have an earlier model VTR so has good first hand knowledge.
Said the holes on the gold valves are larger hence let more oil through, which = less damping.
to quote" The damping on the VTR is not bad at all, but its the springs that are way too soft and really let the package down...You cant walk on oil, its not the oil holding your bike up, hence its not the valves at fault. Its the springs that support the weight of the bike and thats what stops it from bottoming out. The valves just slow the process, but the fork will continue to move until the spring reaches a load that is enough to stop the downward force."
Do you think your suspension tuner would be willing share his VTR fork valve modifcations with us?
Reason I ask is I've been working on this same thing myself.
I've had the valves out three times now, twice porting the valves and this last time changing the shim stack.
Test riding between each change, haven't test ridden since the last change (shim stack), but looks promising so far.
I've gotten pretty good at pulling the valves and am able to reuse most of the oil after pulling the forks apart.
Learning a lot if nothing else.
Anyone here have experience with modifing stock valves and shim stack?
I think it's a worthwhile thing to persue.
Thanks,
~Jeffers
I was going to get the gold valves and this is what he told me.
He has a fair amount of cred in the industry so knows his stuff. Also used to have an earlier model VTR so has good first hand knowledge.
Said the holes on the gold valves are larger hence let more oil through, which = less damping.
to quote" The damping on the VTR is not bad at all, but its the springs that are way too soft and really let the package down...You cant walk on oil, its not the oil holding your bike up, hence its not the valves at fault. Its the springs that support the weight of the bike and thats what stops it from bottoming out. The valves just slow the process, but the fork will continue to move until the spring reaches a load that is enough to stop the downward force."
Do you think your suspension tuner would be willing share his VTR fork valve modifcations with us?
Reason I ask is I've been working on this same thing myself.
I've had the valves out three times now, twice porting the valves and this last time changing the shim stack.
Test riding between each change, haven't test ridden since the last change (shim stack), but looks promising so far.
I've gotten pretty good at pulling the valves and am able to reuse most of the oil after pulling the forks apart.
Learning a lot if nothing else.
Anyone here have experience with modifing stock valves and shim stack?
I think it's a worthwhile thing to persue.
Thanks,
~Jeffers
04-21-2005, 08:41 PM
#2
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Re: Fork revalve, modifing with stock parts
Question for you:
In all the tuning you have done with the Stock valves and messing around with hole sizes and shim stack have you been able to get the sudden "boom forks feel like the bottomed out" when you hit small 1" to 2" inch bumps or curbs like pulling into a gas station.
The Gold Valves fix this completly. I can't speak on the modifying stock valves and shim stack theory, but i can say that i put RaceTech Springs, RaceTech Gold Valves, and Race Tech 10wt oil (as reccomended on the RaceTech site) and my forks are as good as i could ask for. I have ridden several newer (new) superhawks and their forks suck compared to mine.
For what it is worth throw the bucks down, buy the good valve put it back together and forget about it.
In all the tuning you have done with the Stock valves and messing around with hole sizes and shim stack have you been able to get the sudden "boom forks feel like the bottomed out" when you hit small 1" to 2" inch bumps or curbs like pulling into a gas station.
The Gold Valves fix this completly. I can't speak on the modifying stock valves and shim stack theory, but i can say that i put RaceTech Springs, RaceTech Gold Valves, and Race Tech 10wt oil (as reccomended on the RaceTech site) and my forks are as good as i could ask for. I have ridden several newer (new) superhawks and their forks suck compared to mine.
For what it is worth throw the bucks down, buy the good valve put it back together and forget about it.
04-21-2005, 09:21 PM
#3
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Re: Fork revalve, modifing with stock parts
Question for you:
In all the tuning you have done with the Stock valves and messing around with hole sizes and shim stack have you been able to get the sudden "boom forks feel like the bottomed out" when you hit small 1" to 2" inch bumps or curbs like pulling into a gas station.
The Gold Valves fix this completly. I can't speak on the modifying stock valves and shim stack theory, but i can say that i put RaceTech Springs, RaceTech Gold Valves, and Race Tech 10wt oil (as reccomended on the RaceTech site) and my forks are as good as i could ask for. I have ridden several newer (new) superhawks and their forks suck compared to mine.
For what it is worth throw the bucks down, buy the good valve put it back together and forget about it.
In all the tuning you have done with the Stock valves and messing around with hole sizes and shim stack have you been able to get the sudden "boom forks feel like the bottomed out" when you hit small 1" to 2" inch bumps or curbs like pulling into a gas station.
The Gold Valves fix this completly. I can't speak on the modifying stock valves and shim stack theory, but i can say that i put RaceTech Springs, RaceTech Gold Valves, and Race Tech 10wt oil (as reccomended on the RaceTech site) and my forks are as good as i could ask for. I have ridden several newer (new) superhawks and their forks suck compared to mine.
For what it is worth throw the bucks down, buy the good valve put it back together and forget about it.
"boom forks feel like the bottomed out" when you hit small 1" to 2" inch bumps"
That's what I'm working on fixing.
Excessive high speed compression damping.
It's the only problem I have with the front after installing .85 springs and synthic ATF. with 155mm oil level.
And yes, I may end up just buying the Gold valves,
But I can always do that if this dosen't pan out.
~Jeffers
04-21-2005, 09:59 PM
#4
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Posts: 62
Re: Fork revalve, modifing with stock parts
That BANG when riding up a driveway or over small bump is what drove me to this guy in the first place, so at least we are all on the same page.
I have tried to get this to bottom and cannot, with the stiffer springs and the reworked valves, to the point i dont want to ride up the drive way any faster for fear of other bad things, so it has well and truely rectified that problem.
I have come from 10 years on a ZXR750 which is reknowned as having, even today, one of the most planted front ends in the business.... the bike now inspires that same feel and condifence... it really is that good.
As for getting the info from this guy as to what he did ?
I'd say the chances are very slim or none. Thats sorta like asking a magician how he does stuff. : )
The shops name is Biketek, owned by Frank Pons, but they dont have a website, they dont do email and they only take cash lol : ) (search for Frank Pons Biketek and you get an idea of this guys presence in the industry, and why i dont think he give away what makes him good)
Next time im down there i'll see what i can ind out, but in terms of the valves and shims, im a little green as to how the shims etc fit together with the shocks, so what he tells me may make no sense to me.
I have tried to get this to bottom and cannot, with the stiffer springs and the reworked valves, to the point i dont want to ride up the drive way any faster for fear of other bad things, so it has well and truely rectified that problem.
I have come from 10 years on a ZXR750 which is reknowned as having, even today, one of the most planted front ends in the business.... the bike now inspires that same feel and condifence... it really is that good.
As for getting the info from this guy as to what he did ?
I'd say the chances are very slim or none. Thats sorta like asking a magician how he does stuff. : )
The shops name is Biketek, owned by Frank Pons, but they dont have a website, they dont do email and they only take cash lol : ) (search for Frank Pons Biketek and you get an idea of this guys presence in the industry, and why i dont think he give away what makes him good)
Next time im down there i'll see what i can ind out, but in terms of the valves and shims, im a little green as to how the shims etc fit together with the shocks, so what he tells me may make no sense to me.
04-22-2005, 09:34 AM
#6
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Also, if you make the jump to the correct springs up front, be prepared for a raked out position since the front end will no longer be sagged out. After I did mine I had to shim the rear shock about 6-8mm to achieve the correct stance again. Dropping the forks alone was not preferred due to cornering clearance concerns.
my .02
04-22-2005, 11:05 AM
#7
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Re: Fork revalve, modifing with stock parts
I'd hope that whoever does the work on your forks, sorts out the forks preload and correct heights etc. Mine did and the bike is no different from when i put it in there, geometry wise, and I wouldnt expect anything less.
I had already shimmed the rear shock 6mm, a very common mod to obtain "flickability" from the storm. Had that 6mm gain at the rear end been negated by the work done to the forks, it would be felt instantly up front.
What it all boils down to is this:
The bike has a problem with the standard front forks. Do what you want to fix it.
In my case, I sought one of the most respected suspension gurus in Australian road racing, but us aussies are not much chop at racing
and asked him to sort it out for me.
He did just that. I gave him the bike and $380AUD which is about $280US and said fix it.
The bike now has a front end that is planted, solid, stable. No dive under brakes, no pig-rooting on mid corner bumps, and no valve lock when running up a driveway, and i cannot get the forks to lock or bottom out.
Yes he could have charged me extra for gold valves, cause I did ask for them when i dropped the bike off, but on his recommendation I stayed with the current valves.
Not only that, there was no change to the bikes geometry and i was given the option "ride it for a little while and bring it back and tell us what it is or isnt doing and we can sort it out for you"
This is a guy who is good at what he does.
Make of this what you will and argue about the merits of each option and blah blah blah... and while your doing that, I'll be out riding : )
I had already shimmed the rear shock 6mm, a very common mod to obtain "flickability" from the storm. Had that 6mm gain at the rear end been negated by the work done to the forks, it would be felt instantly up front.
What it all boils down to is this:
The bike has a problem with the standard front forks. Do what you want to fix it.
In my case, I sought one of the most respected suspension gurus in Australian road racing, but us aussies are not much chop at racing
and asked him to sort it out for me.
He did just that. I gave him the bike and $380AUD which is about $280US and said fix it.
The bike now has a front end that is planted, solid, stable. No dive under brakes, no pig-rooting on mid corner bumps, and no valve lock when running up a driveway, and i cannot get the forks to lock or bottom out.
Yes he could have charged me extra for gold valves, cause I did ask for them when i dropped the bike off, but on his recommendation I stayed with the current valves.
Not only that, there was no change to the bikes geometry and i was given the option "ride it for a little while and bring it back and tell us what it is or isnt doing and we can sort it out for you"
This is a guy who is good at what he does.
Make of this what you will and argue about the merits of each option and blah blah blah... and while your doing that, I'll be out riding : )
04-22-2005, 11:17 AM
#8
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Join Date: Jan 2005
Location: Western NY
Posts: 347
At 205lbs, the stock springs did not allow me to get correct sag set... with the .90kg springs I did, and the bike therefore sat a touch higher up front. I spend a lot of my VTR time on the track hitting braking bumps on our lovely n.eastern tracks, hard on the brakes, or high speed ripples here and there. .so maybe I notice some hydro lock more than the average street rider.
For the street, I guess the spring mod I did and fresh oil were plenty fine... so yeah, unless you're hitting the track just forget what I said..
;-)
And while you're out riding, I'll be waiting for the next crappy batch of snow this weekend up here in Buffalo, ny.... aarrrgghh!
For the street, I guess the spring mod I did and fresh oil were plenty fine... so yeah, unless you're hitting the track just forget what I said..
;-)
And while you're out riding, I'll be waiting for the next crappy batch of snow this weekend up here in Buffalo, ny.... aarrrgghh!
04-22-2005, 11:42 AM
#10
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Re: Fork revalve, modifing with stock parts
That's EXACTLY why I'm shopping for a cheap dualsport, so I can get my riding fix during the transitional times before and after Summer around here. I'd rather practice sliding the tires on a bike I can dump without crying like a 5yr old afterwards
06-09-2005, 11:32 AM
#11
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Re: Fork revalve, modifing with stock parts
I know this is an old thread, but I want to throw out my experience with fork modding.
I was going to try and retain as much stock parts as possible and then I talked to Roger from Revolution Racing. Awsome guy and very well known in the UK for VTR fork tuning.
Since I'm in the states and couldn't get him to do my forks with his custom parts he helped me to cobble something together.
90kg springs, racetech valves c34 shimset, 5 wt oil, 410mm springs + spacers, 1 mm hole in cartridge body not valves.
OMG what a difference! Front is now glued to the road and confident, but floats over bumps like RR tracks and such. I used to regularly bottom the front under hard braking. Not anymore.
My understanding is that what he does with your forks is even better, but after spending a weekend riding WVa twisties I cannot express the difference in the bike. I got the springs for ~100 and picked up the goldvalves on ebay for 82 shipped. So for less than $200 I got a frontend that is probably better than the rider will ever be.
I was going to try and retain as much stock parts as possible and then I talked to Roger from Revolution Racing. Awsome guy and very well known in the UK for VTR fork tuning.
Since I'm in the states and couldn't get him to do my forks with his custom parts he helped me to cobble something together.
90kg springs, racetech valves c34 shimset, 5 wt oil, 410mm springs + spacers, 1 mm hole in cartridge body not valves.
OMG what a difference! Front is now glued to the road and confident, but floats over bumps like RR tracks and such. I used to regularly bottom the front under hard braking. Not anymore.
My understanding is that what he does with your forks is even better, but after spending a weekend riding WVa twisties I cannot express the difference in the bike. I got the springs for ~100 and picked up the goldvalves on ebay for 82 shipped. So for less than $200 I got a frontend that is probably better than the rider will ever be.
06-10-2005, 08:04 AM
#12
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Re: Fork revalve, modifing with stock parts
Did you come to any conclusion on your stock valve experiments? I'm all for tweaking the stock valves if they are tweakable.
06-10-2005, 11:21 PM
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Re: Fork revalve, modifing with stock parts
Did you come to any conclusion on your stock valve experiments? I'm all for tweaking the stock valves if they are tweakable.
Third time was the charm.
Basically just ported the compression valves the first time.
This reduced HSCD, but it wasn't enough.
Opened the ports as far as the valves would allow and beveled the port edges on the second attempt. (being careful not to grind though the 'O' ring channel)
This reduced HSCD even more, (good),
but reduced LSCD as well (bad)
The third time I resurfaced the valve seat and removed the .005" spacer shim closing off the ports completly until the shims open.
This increased LSCD without increasing HSCD much.
I'm satisfied with the results now.
LSCD is greater than stock
HSCD is lessened from stock
here's the rest of my specs
Mobil1 synthetic ATF (approx 7w), 155mm oil level, .85 springs preloaded to 40mm of sag.
Rebound is not modified and set @ between .125 to .25 turns out from seated.
Thanks for asking,
~Jeffers
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