Gold Valve Question

Got questions? We got answers....
Post Reply
N8Strine
Member
Posts: 264
Joined: 12:15 pm Jan 19 2008
Country:
Location: York, PA

Gold Valve Question

Post by N8Strine »

Hey I have gold valves in my front forks. My buddy has an 07 ktm 250 xc, and he is telling me that most suspension tuners are using the stock valving and just messing with the shim stacks, because the gold valves cause air/oil churning and uneven fork pressure according to what he read on some ktm forums, this may be the case, but would that be the case with our forks too? I need some facts to refute his claims lol. I dunno I thought I noticed a pretty good difference with mine but then again I'd have to ride it with the stockers back in it.
User avatar
Jeb
Gold Member
Gold Member
Posts: 1894
Joined: 08:01 pm Jul 14 2006
Country:
Location: Cincinnati / Northern Kentucky

Post by Jeb »

I've got the gold valves in my forks. I haven't ridden much since I've put them in but enough to get a feel for the difference. I do plan on explaining in more detail once I give them a good whuppin in a few weeks!

A possible question or two for your buds: Is air/oil churning actually bad? What is the result? If I've got this churning phenomena happening it feels pretty good to me!

And uneven fork pressure - is that so bad if you end up with better performance? A fellow in North Carolina does suspension work (brucessuspension.com) and his cadillac service is the "Trail Tamer". Essentially what he does is makes one fork handle all of the compression and the other fork the rebound - how's that for uneven pressure!! In fact, there's suspicion that the effects of the mod may induce premature front wheel bearing wear. The base valve in the rebound side does NOTHING, it's literally just there to hold the fork together. But he's known for the performance his suspension work provides; I know a fella with the Trail Tamer work and he loves it.

BTW I'm not knocking those who elect to send their suspension components to tuners, just those who seem like they need to justify spending some big bucks on suspension by marginalizing a great product like the gold valves.



:grin:
"No farmer ever plowed a field by turning it over in his mind" -George E. Woodbury

CLICK FOR PICS!
Rob
Member
Posts: 8
Joined: 12:26 am Mar 02 2008
Country:
Location: Denver, Colorado

Post by Rob »

The only way the GV will "churn oil/air" is if you have a really low oil level in the fork and it sucks some air into the valve. This would also happen with the stock base valve.

Any valve will create "uneven fork pressure" that's what valves do - they restrict flow causing a higher pressure on the upstream side. It's what makes the fork work.

GVs do wonders for KDX forks. the stockeers have excessive high speed compression damping which transfers every rock, root, & bump directly to your hands. With the properly tuned GV the difference is night and day.

The GV is simply a sophisticated replacement for the very crude stock base valve. But, It IS possible to get considerably better performance from the stock valve. There were some threads a year or so aago on Canadian Dave's KDX forum tellling how to modify
N8Strine
Member
Posts: 264
Joined: 12:15 pm Jan 19 2008
Country:
Location: York, PA

Post by N8Strine »

the word they used was CAVATATING i couldnt think of it earlier.
User avatar
Jeb
Gold Member
Gold Member
Posts: 1894
Joined: 08:01 pm Jul 14 2006
Country:
Location: Cincinnati / Northern Kentucky

Post by Jeb »

Your riding partner may has his phenomena mixed up . . .

cavitation is a term usually used to describe when the pressure in a liquid falls sufficiently below the saturated vapor pressure of that liquid, the result being a violent formation of bubbles because that liquid wants to vaporize, i.e. boil. You see this kind of problem in an industrial setting where a pumping system has either been designed or installed incorrectly or is being operated incorrectly. If the temperature of the liquid is sufficiently high enough (like, close to the boiling temperature of that liquid) such that the suction side of the pump creates enough of a drop in pressure you basically cause the liquid to begin vaporizing - violently - and that damages the pump impeller, shuts down systems, pisses off managers, etc.

The only place I can imagine there's even a possibility of a big drop in pressure is within the compression cylinder, between the active valve on the end of the damping rod and the compression valve (compression cylinder cap) during compression of the forks. And the force required to generate that would not only likely damage your forks but the rider as well.

And if your friends are talkin' cavitation, it ain't air - it would have to be vaporized fork oil. That's the only liquid in the forks to be subjected to cavitation.

I think the air/oil churning sounds much more plausible than cavitation. Yet even that's highly improbable as Rob suggested.

Whatever the case, the bigger question for your friends: exactly what about gold valves causes bubbles (be they air or vaporized fork oil) to get mixed in with the fork oil? The change the gold valves bring about is similar to the change that a tuner would bring about by reconfiguring the shim stack.
"No farmer ever plowed a field by turning it over in his mind" -George E. Woodbury

CLICK FOR PICS!
User avatar
kawagumby
Gold Member
Gold Member
Posts: 927
Joined: 10:09 am Nov 30 2006
Country:
Location: California

Post by kawagumby »

I installed gold valves on the KDX I had before my current one. They worked very well. As is the case for any valving, it must be set up for the type of riding you do, how your bike is sprung vs damping, and your skill level. The gold valves allow more flow than the stock ass'y is capable of and the stack is more adjustable.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
Rob
Member
Posts: 8
Joined: 12:26 am Mar 02 2008
Country:
Location: Denver, Colorado

Post by Rob »

actually, the reason rear shocks are pressurized is to prevent cavitation -the high pressure keeps the oil from going into its vapor phase as was mentioned in a post above. so, it's possible you might see cavitation in a front fork as well. I don't see where it's any more likely to happen with the GVs than with the stock valves. GVs have been around quite awhile now so '08 valving technology has likely caught up or even surpassed them. Our KDX technology is "ancient" so GVs really do do wonders for us.
User avatar
Jeb
Gold Member
Gold Member
Posts: 1894
Joined: 08:01 pm Jul 14 2006
Country:
Location: Cincinnati / Northern Kentucky

Post by Jeb »

>|<>QBB<
Rob wrote:actually, the reason rear shocks are pressurized is to prevent cavitation -the high pressure keeps the oil from going into its vapor phase as was mentioned in a post above. so, it's possible you might see cavitation in a front fork as well. I don't see where it's any more likely to happen with the GVs than with the stock valves. GVs have been around quite awhile now so '08 valving technology has likely caught up or even surpassed them. Our KDX technology is "ancient" so GVs really do do wonders for us.
I suppose the shock needs the pressurization because one unit is doing all of the work so there's more load on it . . . otherwise, why don't we have to pressurize our forks?
"No farmer ever plowed a field by turning it over in his mind" -George E. Woodbury

CLICK FOR PICS!
User avatar
Colorado Mike
Gold Member
Gold Member
Posts: 1921
Joined: 11:42 am Feb 25 2005
Country:
Location: Colorado

Post by Colorado Mike »

We did, back in the mid 70's, my yz had big clunky nitrogen canisters on top of the fork tubes that looked like speedos. Er... not speedos, Tachs.. :oops: anyway, tuning the suspension on that thing was a nightmare, maybe not because of the nitrogen cannisters, but just the whole system was complicated (and heavy) This was the first monoshock system, with the "rear" shock mounted nearly horizontal under the tank. That shock seemed like it was 2 feet long. Diagonal rods went from the swingarm to the shock. The bike had the endearing quality of handling fairly well as long as you were on the gas. If you let off in the rough, it would pitch you on your head. Long downhills were a blast, right up till you ran out of motor. Then you would be airborne and nose down at 60 mph watching the turn fade off to the side, just before you went hay-baling :blink: . I think the guy that designed the rebound circuit on those things had relatives from Hiroshima.
Mike

Life's tough, it's even tougher if you're stupid.
'04 KDX220
Post Reply