450FX Suspension

The stock AT81 rear has been ok, however, not a fan of the front. It slides compared to a 403 or X30.

Lean more...

I learned a little bit the past fall that I'm going to try on my bike from Matt Stavish from Checkpoint Offroad. The rear shock on the FX is 7mm longer than the F. This makes the back end pretty stink bug like. I always felt on the edge of head shake and the front never felt quite planted. Matt did the suspension on Nate Ferderer's ISDE 250fx and for that he shortened the shock 5mm and the change according to him was quite dramatic. He said on my bike he wouldn't hesitate to go the full 7mm since I ride Mostly motocross.

Never figured out why they did that change either, since the MX version already has a little bit too much of that tendency.  The only thing I can think of is that it's to compensate for running the taller 90 tire in the front.  I know it SHOULDN'T be taller since it's a 90/90, but when you put it side by side with any other 80/100 tire, the center knobs make it quite a bit taller.

On ‎2‎/‎9‎/‎2017 at 1:36 PM, GHILL28 said:

Never figured out why they did that change either, since the MX version already has a little bit too much of that tendency.  The only thing I can think of is that it's to compensate for running the taller 90 tire in the front.  I know it SHOULDN'T be taller since it's a 90/90, but when you put it side by side with any other 80/100 tire, the center knobs make it quite a bit taller.

I would add that the rear AT 81 is also a short tire.   If you put most any brand 80/100 up front with a 120/100 rear the bike gets really stink bug.  Forks  can be pushed all the way down and sag can be over spec (Like 110mm) and the bike is still stink bug and it will over steer.  I ran the bike stock and it was working ok and I decided to throw on tires that I  have found work well for the terrain I ride and the bike got really skewed up - Major over steer. Since this time I have done a lot of tire measurements when mounted on the bike at the pressures I use.  Using an M59 front, I need to stick with a 110/100 rear with forks pushed all the way down and sag at 105mm. I also found needed to dial in more rear rebound to stabilize the pitching.  If I want to run a bigger tire in back my next step is to buy a link.

 

So Yamaha had it right with the stock tires and settings, but tire changes that still work are limited.

I just got my suspension back from factory connection and damn it came back awesome compared to stock valving and springs for my weight. It doesn't like to go slow any more but it sure as hell can go fast now. They mentioned putting in a lowering spacer in the rear. As good as the sss stuff is, stock to me felt terribly unbalanced.

On 2/8/2017 at 8:17 PM, tzracer46 said:

I learned a little bit the past fall that I'm going to try on my bike from Matt Stavish from Checkpoint Offroad. The rear shock on the FX is 7mm longer than the F. This makes the back end pretty stink bug like. I always felt on the edge of head shake and the front never felt quite planted. Matt did the suspension on Nate Ferderer's ISDE 250fx and for that he shortened the shock 5mm and the change according to him was quite dramatic. He said on my bike he wouldn't hesitate to go the full 7mm since I ride Mostly motocross.

Very interesting...  the 450FX and the 250FX have exactly the same geometry.  Shortening the shock on the FX is as simple as swapping the "damper rod" ie shock rod, as the FX shock rods are longer than a regular YZ shock rod.  

Is this mod written up somewhere ?   Will the rear tire strike the fender if the shock is lowered ? 

 

 

 

 

Shocks are usually shortened by placing a collar on the shock shaft between the piston and the seal head to prevent it from extending to it's full length.  Because of where the shock is located and how it works, the internal collar only needs to be about a third of the desired reduction in wheel travel.   Since the bottoming limit is not altered by this method, the tire has no more tendency to interfere with the fender than before the work.

You beat me to it. Yes all I did was install a 7mm shim in the shock to shorten the extended length by 7mm. No effect on the compressed length of the shock so the tire won't hit the fender. I also have a Pro Circuit dog bone that lowers the back about another 13mm but I may take that out depending on how things work with the shorter shock. 

I just tweeted Nate Ferderer and the situation is a bit different than what is described above.

Nate races a YZ250F, not an FX.   He runs the FX shock because he says it makes the bike turn better.   He is running a 22mm triple clamp on his bike.

 

 

 

I was referring to his isde bike which was an fx. 

And yes I do know that he has been also racing a 250f in national enduros and such.

 

45 minutes ago, tzracer46 said:

I was referring to his isde bike which was an fx. 

Not according to him.  "I plan to pick up an fx soon".  His twitter is @whoisNatefrog

Edited by MidlifeCrisisGuy

Try a google image search. His isde bike was an fx with American flag graphics from bdmx. Look close you can see the electric starter.

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