What happened to my great YZ450F suspension?


12 replies to this topic
  • red7

Posted February 17, 2007 - 01:36 PM

#1

I bought a new '06 YZ450 exactly 5 weeks ago (January 8th) and have about 20 hours on it. My suspension was a little stiff at first but has been absolutely amazing after it broke in some. Then the past few times at the track I've started bottoming out the front suspension on bigger hits and by the end of riding today it was bottoming out even on anything that I didn't land perfectly. I got back to my house and the forks were totally clean down to a dirt ring 1/2" from the bottom which I believe confirms that I'm bottoming out.

I weigh 180 lbs with no gear on and hadn't touched the clickers before today. Is my month old suspension already messed up?:censored: If I sit on the bike and shove the handlbars down with the brake on it rebounds ok but it does seem soft almost like my WR suspension. Just sitting there shoving it I can get it maybe an inch or inch and a half above halfway compressed. I then turned my compression (by handlebars) clickers 2 clicks in to 9 out and it compressed the same amount. I then did 2 more clicks to only 7 out and it still compressed the same. Would I feel a difference in the clickers just pushing on it or do they not come into play until a ride like situation? I haven't had a chance to go back to the track to see if it's any better with more compression.

So does it sound like something is wrong? Did the suspension just break in this past week? I'd be surprised if by breaking in it goes from sucking up the hits to bottoming out. I have been riding fairly hard for a new rider and have come up short on a few triples (50-60' but not that high) but I see guys case stuff way harder on bigger triples where the impact is much more due to their height and they aren't having problems with their suspensions. BTW- I haven't seen any oil anywhere on my fork. I did one time notice about 5 small drops of oil right beside my front wheel after I came to a stop after hitting pretty hard on that triple I'm learning. I looked all around my bike and couldn't find any signs of anything leaking but it was very strange that it just happened to be right where I stopped which was just off the track.

Man, I just want my great suspension back and am going to be bummed if it already needs work after just over a month. Are these things that fragile? Please help!:ride:

  • grayracer513

Posted February 17, 2007 - 02:55 PM

#2

First, see if bumping the clickers up helped. If not, the next thing you can try is to add 5-10cc per side to the outer chamber oil. Beyond that, you could try a complete oil change and possibly go from the 3wt fluid to a 5wt. It could also be that the springs are just too light for you (what's your weight in street clothes?).

I have seen one '06 that broke the plastic sleeve on the base valve assembly, but I don't know how that affected the operation.

  • Ga426owner

Posted February 17, 2007 - 03:43 PM

#3

record the compression, the rebound and Hi/low speed on both forks and shock. Then increase the dampning compression in the forks a couple clicks to control bottoming
20hrs-25hrs it is time for a fork/shock service - dissassemble, clean, inspect, refill and I replace the fork seals
as it breaks in I find I have to increase compression dampning a couple of clicks when brand new

  • TexN343

Posted February 17, 2007 - 04:35 PM

#4

Does old fork oil really have a huge impact on the way the fork work? Would there be any negatives to changing to a 5wt oil? Would it rebound slower?

  • tmauto69

Posted February 17, 2007 - 04:41 PM

#5

I agree at 20hrs you should be changing fork seals and the oil in the forks.
I weigh 175 without gear and have my comp on 6 out. I mostly ride in the woods with some track thrown in and I will bottom on occasion at the track.
So I would say you are on the light side on the comp

  • red7

Posted February 17, 2007 - 07:42 PM

#6

So do you think the suspension just got broken in and that's why all of a sudden it went really soft really quickly? I'm 180 in street clothes so I'd think the stock springs would be ok for me.

So the forks need to be serviced every 20 hours? How difficult is it to service the forks myself? I have swapped out the springs in my Yamaha Roadstar forks but have never messed with dirt bike forks and I definitely don't want to screw something up seeing as how I wasn't flying through the air on my Roadstar. I live in Mexico now so this is something I should really learn because I won't be going back to the States every month and I'll easily put 20+ hours on each month. I am going to be going back in March so what all would I need to order ahead of time so that it's waiting for me at my home in AZ?

Thanks everyone!

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  • red7

Posted February 17, 2007 - 09:25 PM

#7

A friend just called and is coming down to visit in a week so if I can get some stuff ordered up and sent to him then he can bring it. What all do I need to service the forks, just fork oil and seals? How much oil and what type do you recommend? Do I just need 2 seals, 1 for each leg? Anything else?

Thanks!

  • Ga426owner

Posted February 18, 2007 - 07:40 AM

#8

Red do you have a hr meter on your bike? I assume you have 20+ hrs based on the reading from a Hr meter correct? It seems like you really got to 20 hrs quick from purchase. (just checking)
If you have not ever done a fork/shock service you will need assistance. You also recharge the nitrogen in the shock. I suggest replacing fork seals as well.
I would have a reputable suspension tuner do this/show you how to do the basics. Remove both forks and Shock.

  • red7

Posted February 18, 2007 - 08:51 AM

#9

Red do you have a hr meter on your bike? I assume you have 20+ hrs based on the reading from a Hr meter correct? It seems like you really got to 20 hrs quick from purchase. (just checking)
If you have not ever done a fork/shock service you will need assistance. You also recharge the nitrogen in the shock. I suggest replacing fork seals as well.
I would have a reputable suspension tuner do this/show you how to do the basics. Remove both forks and Shock.


I have a trailtech which tells me cumulative ride times in addition to speed, average speed etc. I mounted it inside my handlebar pad (turned out cool). The only problem is that I reset it several times when I was timing myself for lap times or average speed on laps so I'm not exactly sure on the hours. I've had a few injurys over the past month so I've ridden a bit less then normal but I easily put on 4-5 hours per week so maybe it's as low as 15 hours but I think 20 is pretty accurate and actually doesn't seem like much as that's only 4 hours per week. I've had 2 weeks where I was injured and only rode 2 hours so it could be 15.

So if it is only 15 hours does it sound like the oil wore out and that's why all of a sudden I'm bottoming out or does it sound like something else is wrong? What makes me nervous is that it went down hill really fast where it started bottoming out just out of the blue.

Please advise what all I need to service these as I'm running out of time before my friend leaves to come down. Hopefully it's all stuff I can get from the TT store as I'm placing an order with them for some other stuff. I can take it somewhere here if I ask some of the pros but it would be good to make sure I have the right seals and whatever since ordering from the States is expensive.

Thanks!

  • berudd

Posted February 19, 2007 - 07:10 AM

#10

Well, adjusting the compression clickers would not affect how far down you can push the forks, just have fast you can push them down. They don't limit the travel, they just control it. Heavier springs may be in order. I am guessing it is just now fully broken in. At this point, I am sure that nothing in the forks needs to be replaced but new oil may be a good idea. If you put in heavier fork springs you could change it then.

  • red7

Posted February 19, 2007 - 09:46 AM

#11

Well, adjusting the compression clickers would not affect how far down you can push the forks, just have fast you can push them down. They don't limit the travel, they just control it. Heavier springs may be in order. I am guessing it is just now fully broken in. At this point, I am sure that nothing in the forks needs to be replaced but new oil may be a good idea. If you put in heavier fork springs you could change it then.


So there is nothing I can adjust to limit bottoming out? I thought that's what the top clickers were for. The manual says to turn the clickers clockwise if bottoming out.

  • berudd

Posted February 19, 2007 - 10:26 AM

#12

Well yes that is what they are for but your "sit on the bike and push" test does not show the affect. Not well anyway. Even with the clickers turned all the way in, the forks can bottom if enough force is applied. As I said, they don't limit how far the suspension travels. A better way to think of it is that they limit how fast the suspension moves. If are all the way out, then it will move through the motion quickly and you feel this when you bottom the jump. Turning them in will offer more resistance to the force that is trying to bottom the forks and may prevent the bottoming. Keep in mind and any suspension can and will bottom out if you hit something hard enough.

After reading this thread and the other one you posted about this, I don't think there is anything wrong with your bike. You just need to tune it a bit.

  • red7

Posted February 20, 2007 - 08:41 PM

#13

Well yes that is what they are for but your "sit on the bike and push" test does not show the affect. Not well anyway. Even with the clickers turned all the way in, the forks can bottom if enough force is applied. As I said, they don't limit how far the suspension travels. A better way to think of it is that they limit how fast the suspension moves. If are all the way out, then it will move through the motion quickly and you feel this when you bottom the jump. Turning them in will offer more resistance to the force that is trying to bottom the forks and may prevent the bottoming. Keep in mind and any suspension can and will bottom out if you hit something hard enough.

After reading this thread and the other one you posted about this, I don't think there is anything wrong with your bike. You just need to tune it a bit.


Thanks for the explanation! I went to the track today and at least nothing seems broken. I started by turning in the compression clickers 4 clicks and it still bottomed somewhat so I turned them in another 2 clicks and now it only bottoms on the bigger/flatter landing. Unfortunately, I lost the smoothness of the stroke as I think this stiffened it up on the smaller bumps. Am I correct in thinking that by increasing the oil amount I could stop the bottoming but still turn back the clickers on the compression some so that the stroke isn't so stiff?

I'm relieved that at least the bike is rideable until I get it serviced! I'll be really happy if I can get the smoothness back but without the bottoming out. Does oil level sound like the ticket? Also, what oil do you guys recommend? I use Amsoil shock therapy in my Roadstar but that's a totally different fork. Do the forks need to be totally taken apart every time or can I get away with dumping out the oil and refilling with fresh oil? If not I'll have to wait until I go back to the States in a March or April and have them serviced.





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