YZF Suspension Midvalve??
Posted November 02, 2001 - 03:51 PM
This past weekend I had an accident at a local track in Splendora, TX. I broke my collar bone and I will be "out of order" for 4-6 wks. I was jumping a 140ft triple step up and was in 4th gear wide open (approx. 65 mph). After thinking long and hard about why I wrecked I have come to the conclusion that my stock suspension cant cut it for me anymore. I believe this accident could have been avoided if I would have had suspension set up for my weight/skill level! Right now my suspension is stock (still at the stock clickers and I have ATF in the forks). I weigh 168lbs w/o riding gear...I ride only MX and I am a fast intermediate rider.
I have read previous posts of people removing the mid valves, changing compression stacks, and replacing shims/etc. Scott F and DaveJ are very knowledgable in the suspension area and I would like to hear what you guys think! Are bottoming cones the way to go?
I know 95% of people send their suspensions to reputable shops and love the results. But I am not like 95% of the people and I enjoy working on bikes and am very mechanically inclined. I would like to "set up" my own suspension and be able to change setting from track to track. I am just picky about who sets up my bike (and I believe in the old saying, "no one cares about your bike like yourself" ) I would like to spend my hard earned money on "making my suspension work for me" and would like to keep the cost to a minimal if at all possible.
Basically what I am trying to say is: what combo do you guys recommend for me? What oil/spring rates work the best for MX applications? What should I modify internally in my forks? I read where DaveJ said, "The combo of bottom cones, ultra-adjusters, and mid-valve installed is a good one". Any comments?
I would really appreciate what you guys have to say! Because I am getting tired of wrecking due to lacking suspension! I have taken apart forks on about 20 bikes to replace seals/oil/clean etc... and have a "general" knowledge of how suspension works. And I now have alot of free time since the recent accident and would like to "set up" my suspension very soon (within 2-3 wks)! So I would really appreciate your comments! Thanks a bunch,
Posted November 02, 2001 - 06:01 PM
He has set up my suspension w/ removal of midvalve. I am very happy with results. .47's,goldvalves, 95-100mm height ---still debating the cones, need more testing. DaveJ/ScottF are super knowlegable in this arena also. Get well soon.
Posted November 02, 2001 - 06:20 PM
On your suspension, did you have the oil level up around 95-100mm? That is the first fix for bottoming but if you have the time, skill or money a revalve is best.
Posted November 03, 2001 - 04:38 AM
There is a reason for the midvalve, when the first ones popped up inside 92 CRs, they werent a very good design, but they started the ball rolling.
All modern MXers use them, including works suspension...There is alot of performance to be gained by a CORRECTLY set up midvalve.
Midvalve float is just one factor upon setting up the midvalve, "float" being the distance the shim stacks travels before bottoming against the cup washer and being force to deflect which gives you the "damping".
Float distance determines at what shaft speed the midvalve will be effective. A midvalve set up with a shorter float distance will start providing damping at a lower shaft speed than one with more float.
Typically MXers like a midvalve set up with less float because it provides more bottoming resistence on jump take offs and jump landings.(which are low speed situations).
The 00 YZs had issues with thier midvalves, they actually worked pretty good for about 15-20 hours then the face shim of the midvalve stack would distort due to overflexing.
In 01, Yamaha increased the float by 1mm(which is a a huge increase) to try and remedy the problem. The float is so huge that the shaft speed has to be extremely fast before it comes into play and therefore it is basically useless.
Instead of testing and designing a new shim stack (which takes time and effort and $$)that would hold up and offer the rider better margin of suspension, some tuners just take out the midvalve shim stack (and any additional performance along with it) and try to pile all of the compression damping on the base valve.
This is another great topic......
Take Care, John
Posted November 03, 2001 - 05:49 AM
I read in your profile you are an MX Tech suspension guy! I know MX Tuner is too (so I will send him an email later today).
So anyway John what would you recommend that I do? Are the bottoming cones worth the cash (I thought the 01' came w/bottoming bumpers?) What about the ATF what do you think? (there is ALOT of disagreement about this stuff?) I ONLY ride MX and am a fast intermediate rider 168lbs w/o gear! Im sure you could give me a good "starting poit" which would be more on par than right now! Like oil height, clickers, new springs, valving, etc!
For my skill and weight do I need new springs (stock is .46 and 5.4 right?) Im sure someone on this board could recommend a good starting point? Thanks for the help,
Posted November 03, 2001 - 06:37 AM
Complete revalve, much heavier spring,.
.48 with 10mm of preload, 7w OIL@120mm. raised 12mm(much better turning). As far as clickers go, thats a personal preference. Doug runs heavy springs with very progressive damping. I don't have bottoming cones, but I hear they are pretty sweet.
6.0 spring, again heavy springs with very progressive damping. Clickers , personal preference.
My riding time is very limited, I would like to learn how to set up my bike also, getting into the internals and all,so I prefer to have someone else do it.
I really can't say enough about his work, and ofcourse, he will work with you to get it right.
There are alot of options for suspension service, but I can tell you first hand, he does all the work.
Posted November 03, 2001 - 07:24 AM
The ATF debate is very simple. It is not a direct replacement for the stock fluid. It IS a viable alternative *IF* you revalve to compensate for the thicker fluid. If you sue it as a stock replacement, you'll give up plushness (of which I put a premium on).
The Midvalve debate. Personally I think they suck. They add another variable that, for me, creates a more difficult tuning issue. There isn't a thing in the world wrong with letting the compression adjuster do the damping alone. If John can make forks work with the midvalve, then there is absolutely nothing wrong with that. I have excellent success without them. So who is right? Both of us. Will my "midvalve" damping ever change? Nope, it can't because it ain't there.
Bottoming cones. I've never had to resort to using them. Would my set ups improve with the cones? I don't know. I've never used them. I've never had an issue I couldn't resolve without them.
Spring rates. I prefer to use the softest springs I can to give the desired results. This means the 170 lb rider isn't going to need to go to the .47's all the mags recommend. Stiffer springs prevent the front end dropping in a corner. This isn't good for cornering. The front end *needs* to drop to promote good corner carving.
I know this doesn't give you the specific answers you wanted. Basically you need to ask one person and try their set up. You start mixing different set ups and you can get a miserable handling bie that doesn't supend well at all.
I have way too many customers who will ask 5 different guys around here (most of THEM being parts caunter guys -generally the clueless variety) and believe the person who gives the the answer they want to believe, for whatever reason, instead of who they should believe. This falls into the category of tying to convince someone I know what I'm doing.... which I won't do.
Posted November 03, 2001 - 11:05 AM
Thanks for a honest opinion! I appreciate it! So you think I need softer rate springs?
Posted November 03, 2001 - 03:14 PM
Sorry to hear about the collarbone. Get well soon.
Regarding, the YZ's mid-valve, I am currently riding an '01 YZ-250 (and have had several YZ250's over the past 2 decades). I know, I know, this is a 4-stroke forum, and the reason I partake is that at 36 I am seriously considering a '02 YZ-426F!
Back to the suspension question. I have had good luck w/both my '00 & '01 YZ-250 by having my local Race-Tech guy change out the mid-valve and replacing it w/a check style valve. Using the correct springs (.46) and a 95mm oil level this has worked great for my VET intermediate, (6'3", 220lbs) ability. Basically, I have gone this route as a cheaper alternative to Gold Valves (which I used w/great success in my '97 & '98 YZ's) Using the check valve is by no means a step back as someone posted above. Paul Thede the Race Tech guru has this suggested for all YZ forks! The stock mid-valve is overengineered and is very easy to blow through if you are fast or over 200lbs. If you couple this w/the Gold Valve or even better, the Delta Valve you will have sweet working forks.
Just my .02c
Posted November 03, 2001 - 04:38 PM
I'm in kind of the same boat as you. My suspension works volumes better than the 00 250 I got off of but it's still way too stiff. I've been going through the dilema of how to do my suspension. If you want to do it yourself, it has been recommended to me by several to go with Race Tech. To my knowledge they will send you a video and good support if you want to do it yourself. (I haven't personally tried them, only feedback I got.) I was going this route but I have a friend who's dad is a Pro Action dealer out of Wis. and he is giving me a break on cost and setting it up for me about as cheap as i can purchase the Race Tech stuff.
As for the oil, I just drained my stock oil and it was clumpy after 3 weeks of riding. It was about like old motor oil with 50k miles on it. I'm going with the Race Tech oil and it really softened my front end up and made it work a lot better. (Springs are still too stiff however.) I have been warned to stay away from some oils like silkolene in the Kayaba forks. I have first hand experience how the oil gets real inconsistent when the forks heat up. They recommended going with the Kayaba fork oil. They told me if I didn't believe the other oils were bad, measure the sag on the front when the bike was cold. Go out and ride it for a while and remeasure.
As for spring rate, you can find it in a lot of readings on the internet. For the front, I believe the sag should be between 15 and 40 mm (Not sure of exact but there abouts.) For the rear, set your race sage between 90 and 105 mm and then check your static sag. If it's less than 15 mm, the spring is too soft. If it's more than 25 then your spring is too stiff. (Sounds backwards but it's right.)
Posted November 03, 2001 - 04:47 PM
Thanks for the tips I will take them into consideration when I purchase new stuff for my forks! Hopefully we will see you soon with a 02' YZ426 (you will never go back to 2 smoke again LOL)!!
Right now I am at stock springs and stock clicker settings on a 01' YZ426 the only difference in my bike is I have Mobil 1 Syn. ATF in the front forks and the recommended standard oil height which I think is 130mm. I have plugged my weight into about 3 charts and they all point at .44 for the front forks! If I change out my front springs Im sure it would make my bike fell unbalanced right? So I would have to goto like a 5.0 in the rear? Please let me know what you think and tell me if I am "off course" here...I am just a newbie at suspension so thanks for bearing with me (the only thing I have done suspension wise is change fork seals and I have done like 20 of them)! I one day hope to learn suspension well, and be able to apply my knowledge and help others! Thanks a bunch,
Posted November 04, 2001 - 03:24 AM
Personally, I'd lose the ATF, use 5wt Bel-Ray HV-1 susp fluid and run it at about 95mm. Back the compression clickers out until it begins to bottom slightly. This is about as good as you can do with stock forks.
The biggest disadvantage with sending your stuff to Pro-Action (or most other shops) is the fact if you don't like it, you have to send it back to them. With Gold Valves (installed by yourself) you can go in and swap shims in about an hour. Besides, I can beat any of Pro-Actions forks hands down in plushness and bottoming resistance without harshness with Gold Valves. I guess you can tell I've never been positively impressed with any of PA's work.
Garrett, if you want to do the Gold Valves, I'll give you a valve stack recommendation. I wouldn't use RT's stack. It'll be too harsh. I can answer any questions you have better than RT's dorks can. Don't expect a quality answer from the guy on the other end of the phone. Seems doing bong hits is a part of a good breakfast out there. And DON'T even think about the Delta Valves. Way too much trouble to get right. And once you do, don't touch the adjusters or you'll end up starting from scratch.
Posted November 04, 2001 - 06:10 AM
I really appreciate your quick response!!
Thanks for the tip about the ATF...I will give the 5wt Bel-Ray HV-1 a try!
I know a few people (from the track) who hated there suspension more after they sent it to a shop for a revalve (and the shops are out of state )...just like you where saying! That is why I would like to learn how to do this myself. I can split cases/top ends, etc, and do any engine work...but I havent learned suspension yet!
About the Gold Valves...I installed Gold Valves on 1 of my previous bikes (and another set on a friends bike) and they were great (it gave you much more adjustibility and plushness)! I never swapped shims on a gold valve (but it didnt look hard, just take the nut off and restack am I correct?)
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:<HR>Garrett, if you want to do the Gold Valves, I'll give you a valve stack recommendation. I wouldn't use RT's stack. It'll be too harsh. I can answer any questions you have better than RT's dorks can. Don't expect a quality answer from the guy on the other end of the phone. Seems doing bong hits is a part of a good breakfast out there. And DON'T even think about the Delta Valves. Way too much trouble to get right. And once you do, don't touch the adjusters or you'll end up starting from scratch.[/QUOTE]
Yeah, I would appreciate if you could give me a valve stack recommendation for the Gold valves!! I was planning on ordering them next week and this was the "push" I needed! I never have used the delta valve (and I wont ever use it now LOL)! Yeah I knew RT's guys dont know which end is up, I called up there about a yr ago and asked what fork oil they recommend...of course it was the $60 a qt. bottle! LOL Well anyway I really appreciate your help. Hopefully I will know enough when I get through with my suspension to help others with the same problem! Thanks,
Garrett Berg (firstname.lastname@example.org)
Posted November 04, 2001 - 04:28 PM
Sorry to hear about the miss hap, and hope you're healing well.
Not sure what the details of your jump were, but I'll have to assume you cased it. Which means mid-valve or not, or bottoming cones, you most likely would have ended up in the same condition.
Going forward, for your level of riding, I think I would leave the mid-valve in.
I only recommend its removal for trail or technical riders that find the YZ factory setup too harsh on high compression movements.
However, bottoming cones are a nice addition, but do little for the majority of suspension usage.
As for valving, I think the factory unit is hard to beat, (however, Race Tech stuff does work and the convenience of their valving stack sheets can make it easier for those with less experience).
Perhaps you should share what you don't like about your ride and what your expectations are for future performance, (and the details of what went wrong with your jump). Then perhaps we can narrow down on some recommendations.
[ November 05, 2001: Message edited by: DaveJ ]
Posted November 04, 2001 - 05:26 PM
From what I am told (I was knocked unconscous and dont remember a thing about the wreck) I had been clearing it all day long just fine. But the time I wrecked my bike started to get headshake on the straight away before the jump and I continued to "pin in" in order to clear the jump. Well in the air my bike was nose high and I landed like that (on the rear wheel) and the force from going 65mph slapped my front end down and this is what caused my wreck (keep in mind it is a step up and it normally is a smooth landing jump)! I went over the handlebars and tucked and rolled and this is what broke my collarbone!
The reason I know my suspension isnt the greatest is: I was riding with 2 guys at the track (one was on a CR450 and the other on a YZ426) They were easily pinned out on straight aways (with no headshake) While I was struggling to keep my front end from swapping back and forth! Thanks for your help,
Posted November 04, 2001 - 06:51 PM
Lets get back to the basics:
1. Get the correct springs, YES, they are important. Headshake is a direct result of your bike being unbalanced. Due this before spending any money on any valving.
5.2 shock .44 fork
2. As far as bottoming cones go, let that be the last item on your list....reason being is that the stock bottoming bumpers due a pretty good job. The stock bumpers are of a "closed cell" design, Yamaha was working with "open cell" bumpers, that of like on your shock. The open cell design had superior bottoming properties but they were deteriorating in the fork fluid, causing contamination. They went with the closed cell (like a pencil eracer), they gave up some bottoming resistance, but the the material doesnt break down.
3. Do a complete teardown and inspection. (there is a procedure I posted somewhere around this site, let me know if you cant find it) replace any worn components. I guarentee the face shim on the midvalve (active valving)will be distorted. No problem, you can buy replacement shims from any major suspension dealer.
It is very important that you do a very thorough inspection, only way is to COMPLETELY teardown the components, I am talking complete disassembly of the base (passive)valving and midvalve (active) compression and rebound shim stacks.
Also check to make sure that the stock stacks are correct. I have seen stock rebound stacks built incorrectly from the factory. The best way is to get the actual stock stack build that the fork was designed with, the new MX-TECH website(should be up late monday) will have most of the late model bikes build info. The quick way is to lay out both stacks from each fork leg and compare, if they both are the same, you might be ok. Do this check on all valving.
4. Use a quality suspension fluid, Belray or Mobil 1 ATF. I havent heard any arguement here worth anything (except unsupported speculation )why ATF wont work.
5. I would set the fluid height at 90mm for good bottoming resistence. Fluid height only impacts the 2 to 3 inches of travel.
Good Luck, John
BTW...Cool website 393!!
[ November 05, 2001: Message edited by: John Curea ]
Posted November 05, 2001 - 08:58 AM
Hope you get ridin soon...was nice to meet you and your Dad at Motoplex 2 weeks ago.
Posted November 05, 2001 - 10:06 PM
Thanks for the post.
Here are some considerations you may want to look into.
First, the bottoming cones that we are discussing are hydraulic. Meaning that they replace the existing seal head assemblies. Based on your post, I'm under the assumption that you're talking about the bumper assemblies beneath the fork caps. This style of bottoming cone(s) is highly recommended for more aggressive riders, as it appears Motoman is.
Secondly, I'm a little concerned about the application of ATF fluid as a replacement fluid in these particular forks. Yamaha and KYB have only spec'd one fluid grade and that's an 01 at 5 weight. This could be a concern based on the proportion of fork load applied hydraulically to that of the spring. In other words, it may over load the system.
You may want to contact KYB directly for their advice on the use of ATF in their forks.
In addition to this, I think you'll find that headshake, in Motoman's case, is caused by in in-balanced in the bike. This can be the result of weight distribution between front and rear, and/or in equal performance between the two forks.
Let me know if you need further detail on that.
Lastly, a spring setting of 5.2 and .44 is far too low for his level of riding and weight. Perhaps you were thinking of a more conservative trail set up. My recommendation would be at least 5.6 and .47. You may want to spend some time discussion spring weights with the factory teams if you have a connection.
Hope this helps and if I've missed something please let me know.
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