YZ85 forks/ Race Tech/ Yamaha parts availablity

My friend and I both rebuilt the suspensions on our sons' YZ85s recently. They both race Supermini and Senior classes and each have two different YZs for a total of 4 bikes. It was partly for periodic maintenence and partly to change the valving and springrates for the growing boys.

I also installed Race Tech Gold Valves using RT's charts and recommendations, just like I had done years ago on my WR400. I happen to like Race Tech products if for no other reason than they don't treat you like you are too stupid to do something as simple as fork & shock rebuilds yourself. That's a long way from knowing what valving changes to make or being a suspension "expert", but their recommendations have worked well for both me and my son, and the changes themselves are simple to make. You also come away understanding the basics of how your suspension works and that helps greatly for fine tuning.

The problem we ran into on 3 of the 4 bikes was not RT related. It was the shim/bushing that is found between the top of fork cartridge and the bottom spring coil. The "bushing" (there is no known official Yamaha/Kayaba name for it as I will explain shortly) lightly press-fits into the top of the cartridge using just finger pressure. It is "T-shaped" in crossection and provides a flat surface for the bottom of the fork spring to rest against while keeping the bottom-out cushion inside the cartridge and protects the cartridge itself from the sharp spring. It has a locator notch and cannot move or rotate when installed on the cartridge.

Apparently, the spring DOES rotate a bit as it compresses, because the very sharp bottom edge of the springs on 3 of the bikes had chewed through the thin flat portion of the bushing. The damage extent ranged from minor to severe as a couple forks had the bushings dump out in pieces when we dumped the oil.

Our bikes ranged in age from '03 to '05. Surprisingly, it was our oldest '03 that had no problems, while the '05, recently purchased from a very aggressive rider with (what I found out too late) a "zero-maintenence dad", had nothing but chunks and pieces floating loose in the fork tubes.

No big deal. These are small, inexpensive wear items, right? We'll just order new ones along with the new upper and lower tube bushings and the seals. WRONG! Yamaha does not even list those bushings! Their parts list exploded view does not even show them! The ONLY way you can get those 50 cent bushings is to order $325 apiece entire cartridges!!! This is crazy!

I tried to track down Kayaba's website, but only got Kayaba USA, which only manufactures automotive parts; not motorcycle. They referred me to Enzo Racing, the USA Yamaha/Kayaba team. "If they can't get them, nobody can."

Enzo Racing replied to my email right away and said they would do what they could to obtain the proper bushings for me. They also said it wasn't a problem they ran into very often. But then, how many YZ85 forks do they actually rebuild? Maybe a bunch, but I'm guessing probably very few compared to the big bikes. Well, it appears they can't get them either since I have never heard back from them. The same went for Race Tech.

I asked RT how they dealt with this issue since it must be fairly common if 3 of our 4 bikes had the problem to one extent or another. If you have ever dealt with RT, you will quickly learn to save your breath when calling the Tech line and just ask for the shop in the first place since you almost always get a salesman instead of an experienced actual technician on the tech line. The sales guy said they just make the customer buy new cartridges (??!!). The tech guy in the shop said to use a flat spacer bushing (fork spring shim included with RT front springs) on top of the cartridge to replace the bushing.

Now, I can see where Kayaba should have done exactly that in the first place (placed a flat shim between the bushing and the spring bottom). That would have eliminated any chance of the sharp, rotating bottom edge of the spring galling and destroying the stationary bushing. But if we just use a flat shim now without the bushing, I can't help but worry a little there might be a slight chance of it somehow shifting enough to either interfere with the little bottom-out knob on the cartridge rod, or to allow the bottom-out cushion to ride up on that rod (that shouldn't matter too much though), from the way it looks to me.

I am trying the "flat-shim" approach right now as the Race Tech techie suggested. So far, so good. And the suspension is much improved with the RT valving. I'll be taking the forks back apart in another month or so to see how the internals and flat shims are fairing.

If anyone has any good ideas about getting the correct part, I'm all ears. I will NOT buy $650 worth of cartridges to replace perfectly good ones just to get those cheap little bushings.

I strongly recommend that any YZ85 dads out there check their forks at least once a year and at least do oil/seal changes. That seemed to have saved our '03's bushings. While you have the forks apart, put in a proper-sized flat shim (used to adjust fork spring preload, but usually installed at the top of the spring betweem the spring and cap) between the cartidge bushing and the spring to absolutely ensure no future problems. You can get them from RT.

It MUST fit with very little clearance between the shim outer edge and the fork tube inner wall to ensure it cannot slide around much. It also MUST have a large enough inner hole to allow the "knob" on the cartridge rod to pass easily through no matter how much the shim can slide sideways while at the same time being small enough inside diameter to not slide down over the cartridge.

The YZ85 is the best 85cc bike out there and it's ultra-reliability and toughness is one of the biggest reasons why. I also like Race Tech products and the results we've gotten with them, and, if you are persistent enough, the tech support you can get from them, too, though that seems a little more difficult each year. It just ticks me off that such a simple wear item, like that bushing, cannot be obtained anywhere. I do not like feeling as though I am cutting corners or "making do" with flat shims when my son's safety literally rides on that suspension.

Incidently, if you find the valving and spring recommendations given by Race Tech work well for you like it does for us, you should not be afraid to rebuild and revalve your own suspension on these bikes. I made the only special tool besides a fork seal driver and 12mm hex socket needed, a cartridge holder, myself, and, aside from having a shop do the nitrogen charge on the rear shock, it is very easy to follow the instructions and videos. No voodoo involved. If I had to cough up $350 to have a shop redo the suspension every time my son grows 10 to 15 pounds or gets more aggressive, it would be very expensive. He was 75 pounds when he started on the YZ85 and is now 117 pounds less than 2 1/2 years later and hitting a renewed growth spurt.

As for the Race Tech bad-mouthing I saw in another post: Pay someone else to do your suspension and remain ignorant of what it really has done to it and what makes it work. You could do the same for top-ends and valve lash settings, too, if you have the money. Some of us like doing things ourselves or MUST do things ourselves to afford the sport. Who is "the best"? No one can possibly answer that question since no one has tried every suspension company and no two riders will like exactly the same thing.

I actually had one local suspension expert, a good one, compliment me on how well my son's suspension looked to be working while watching him on the Supercross track. He even admitted he had never personally liked RT gold valving, but he sure couldn't argue with the results he was seeing on that bike and said he wouldn't pretend he could do it any better, though he did make a few clicker recommendations, which did help on that track.

If and when the day comes when a suspension tuner guarantees significant improvement over the RT suspension for a reasonable price or my money back, AND the stopwatch and kid agree it is better; AND he is present at the track to actually watch the bike and kid together on all of the obstacles and fine tune it; I will take him up on the offer. Until then, the RT beats stock by a long ways.

Is this the part in question?

<a  href=http://img81.imageshack.us/img81/4409/kybscanmediumwz3.th.jpg' alt='kybscanmediumwz3.th.jpg'>

Uhhh? John...some of us are OLD and blind...could you make that alittle bigger please?



Click on the thumbnail, it should enlarge. Let me know if it doesnt.


This might be a bit easier.....

<a  href=http://img81.imageshack.us/img81/4409/kybscanmediumwz3.jpg' alt='kybscanmediumwz3.jpg'>

Yup, John, it sure is! "Spring seat; top of cartridge." I see German wording; where did you get that photo? Like I said, my Yamaha dealer doesn't even have a depiction or part number for those. He tried real hard for me, too. The Yamaha exploded view of the forks just does not show or list them at all.

The wavy insert part keeps the plastic washer and bottom-out cushion in the cartridge, and the flat part takes the abuse from the bottom of the spring while giving it something wider to sit on than just the top edge of the cartridge. The springs seem to eat them readily.

You've definitely got my attention, John...


The sec one worked fine...very nice!

That little cartidge holding socket is cool, too. I made one from copper pipe and copper fittings that just happened to grab my eye at Menards when I was working on the forks. I had, at first, made one from pvc plastic pipe that lasted just long enough to get one fork cartridge out. Once I was that far, I could then use my dremel to make a more durable and accurate tool out of the copper. Even my snap on impact could not seem to remove the base valve quickly enough to keep the cartridge from spinning without a holder on those forks.

The reason your dealer doesnt have these parts is because he's not a Kayaba dealer.

The seats are cheap, 2.00/ea. They usually come from Europe, the shipping can be expensive.

The seats are very durable, the two main reasons these parts fail:

1. Incorrect installation. These little buggers like to fall out of place during assembly. Use a touch of red locktite and keep spring tension on them during compression bolt installation (especially with an impact). The vibration will knock these seats out of place unless you have spring tension on them.

2. Improper fork cap/piston rod engagement. Make sure the piston rod bottoms into the cap before the jam nut is enagaed. If not, there might not be positive tension on the spring causing the spring to be loose and let the seats get knocked out of place.

Heres the more expensive solution... :thumbsup:

<a  href=http://img170.imageshack.us/img170/9594/factory06kk3.jpg' alt='factory06kk3.jpg'>

With the exception of our '03, which had good ones and have been regularly maintained by me, none of the forks had been apart before to the best of our knowledge (our '05 was purchased used from a guy who doesn't own or use tools; and it showed).

You are 100% correct about being very careful when reassembling to make sure they don't move or fall out, though. They are a very light press-fit. I spread the little wave inserts out a bit to help keep them in place better. I like the red loctite idea. And I do not use an impact for assembly; just a torque wrench. The impact was for disassembly.

But I really have to disagree with their durability. I saw 3 of 4 bikes with failed ones. That's proof enough to me. They are so very, very thin and they are not "continuous" around their perimeter. They have notches to match those in the top of the cartridge. It looks like the sharp trailing point of the spring coil can catch in the notches and really go to work on them. Probably pop them out of the cartridge, too. I still think a flat spring shim in between the spring and this spring seat would totally eliminate the problem. I'll find out, since that's how I put the good ones back together. They needed shimmed for recommended preload anyway.

I any case, do you know who I might contact to get some of these, John? The shipping, though overseas, can't really be too bad on such tiny parts and the right parts are the right parts, wherever you find them. I'd make it worth the effort and order about ten of them. I was under the impression from Kayaba USA (automotive only)that Enzo is a Kayaba dealer? Is that not correct? Are you a Kayaba dealer? Are there any in the USA?

Thanks for all the help, John. Its been along time since I came to TT since 99% of my race bike world revolves around just the YZ85 2 strokes my son races these days. I see there is even a 2 stroke forum now. It's good to be home!

I see German wording; where did you get that photo?

it's dutch not german and the photo is out of the (europ.) Kayaba catalog :thumbsup:

Thank you Frezno. I wonder why they are available in Europe, but not here..? I also wonder if Taffy is still around and could check on their availability in England...

I wonder why they are available in Europe, but not here..?

what, the catalog or the spring seat tops?

you can download the lastets Kayaba catalog from the europ. Kayaba distributor as pdf:

Kayaba Catalog 2006

As John already mentioned the spring seat tops aren't that expensive, 1.20 Euro which is abou $3 due to the weak Dollar (or strong Euro) right now.

Shipping could probabely be done with an airbubble envelope and shouldn't cost that much ($10 just a guess).

But i can't believe those parts aren't available in the US

Thanks for the link to that catalog. I appreciate it.

Me too. Hopefully I can order them. If they are only available from a Kayaba dealer, I can't seem to find a USA one, so, yeah, it looks like they are only available in Europe. That is what is so frustrating, I figured they were an inexpensive part, and a wear item to boot, so I don't know why Yamaha can't get them. And I find it very hard to believe that out of thousands of USA YZ85s that ours are the only ones needing them. Maybe so, but I'm guessing most YZ85 owners just haven't looked.

That's the trouble with letting suspension work intimidate you. If you don't have the money to pay a suspension shop, you just leave it alone and put it in the "automatic transmission" category of black magic and voodoo. If you do pay a suspension shop, do you think they will hold up the reassembly of your forks (and their payment) for such a small unobtainable part? Some might, but I'll bet many will just put in a flat spring shim and keep their mouth shut about it.


You mentioned using a shim of sorts to replace the spring seat. Whats holding it in place and preventing it from getting smashed by the hydraulic bottoming cone piston...??


It's a spring shim, John. It is large enough in outside diameter that it cannot move sideways in the tube very much at all, while being small enough in the inside diameter that it stays on top of the cartridge (can't slide over it). The rod, including the bottom-out knob (for lack of a better description) can pass freely through the hole no matter how far the shim might try to slide sideways (it can't very much). The only thing holding the shim in place is constant spring pressure, which is about all that held the stock spring seat in place. Like you said, they can fall out very easily if you're not careful.

I don't like it (the improvised spring seat/shim) very much, but it does seem to be working and I had no choice since that factory spring seat came out in pieces when I first dumped the oil. The sooner I can get the right parts, the better. I just can't find a Kayaba dealer.

What I want to know is how in the world the spring stayed on top of the cartridge tube without slipping down over the edge, at least partly, without these spring seats being intact. We just bought the bike (used '05), and the first thing I decided was the forks sucked since he could only get about 5 inches of travel. I originally thought the previous owner had overfilled them, but maybe the missing spring seats and chunks of them floating around was why. The forks work fine now, but I am not comfortable with the "fix".

What I want to know is how in the world the spring stayed on top of the cartridge tube without slipping down over the edge, at least partly, without these spring seats being intact.

The spring guide keeps the spring centered, I'm sure it wobbles around a bit at full extension. As the fork compresses the spring guide aligns the spring to where eventually it is centered over the cartridge.


PS I can get you the spring seats, I sent you a PM.

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