Big Guy, Stock suspension motocross

7 replies to this topic
  • j.rush337

Posted March 03, 2014 - 07:35 AM


Hey guys just picked up an 07' yz450f Saturday, trying to get back into riding,never been to the track until recently and im hooked, my question is i weigh 280 pounds not fat i just work out alot, and im 6,4. I was wondering how the stock suspension should hold up like if im trying to hit jumps and stuff, and if i would be all right with my stock for a while since im a beginner, till what point do ya'll suggest i should start messing with suspension. thanks for the help guys.

  • grayracer513

Posted March 03, 2014 - 07:55 AM


Stock suspension is intended for riders weighing between 170-190/195.  You need springs at a minimum.  Your overall experience with the bike will be vastly improved, even in a strictly recreational, non-competitive environment.  Start trying to nail 50 foot doubles as seriously under-sprung as your bike currently is and you'll be running the risk of breaking something.


I'd go with .52 or .54 in the front and a 6.0 or 6.4 rear.

  • j.rush337

Posted March 03, 2014 - 08:08 AM


thanks for the input, 

  • JLB943

Posted March 03, 2014 - 09:03 AM


The bike will feel and act terrible. Having it bottom out all the time and feel like it is wallowing will kill the confidence you need when starting out. You will be shocked how much better it is with proper spring.

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  • j.rush337

Posted March 03, 2014 - 10:23 AM


Ok i just got off of racetech and priced springs, what tools will i need to change them, and 1-10 how hard is that job, thanks again

  • grayracer513

Posted March 03, 2014 - 12:10 PM


The rear spring is a piece of cake.  Fronts are a bit trickier, but not difficult.  You will need only a 49mm octagon box wrench to unscrew the caps from the tubes with, and a slotted piece of metal to use as a rod holder, as shown in the manual. 


Manual: http://www.yamaha-mo...uals/index.aspx


The manual is very confusing regarding the matter of the "jam nut gap".  This post was written in an effort to clear that up: http://www.thumperta...k/#entry6860151


Remember, before you remove the rebound adjuster from the bottom of the fork, turn one all the way in, counting clicks as you do.  Stop when you just bottom out the clicker, and record the number so you can return to that setting after you assemble the fork.  Then, be sure you turn the clickers all the way out until they stop before proceeding.



  1. Loosen the "caps" and remove the fork legs
  2. Remove the caps (actually the cartridge.  It will not come all the way out yet), and drain the fork
  3. Screw the cap in a turn or two and invert the fork.   Remove the rebound adjuster from the axle lug
  4. Compress the fork enough to expose the damper rod jam nut and slide a rod holder under it (feature may be included on the ring wrench for the caps, or a pair of needle nose pliers may be used CAREFULLY.
  5. Loosen the nut, remove the rebound adjuster, and the rebound adjuster push rod, then stand the fork upright, remove the cartridge, spring seat, and spring.


Assemble in reverse order.  Add 345cc of light fork oil 3-5wt. to each side.


This will not change the oil in the inner cartridge.

  • blurz28

Posted March 03, 2014 - 05:26 PM


I was kinda in the same boat..... Except I'm 5'9 and 260 not fat just solid build. Most people guess me at 180-190lbs...
Anyway, I raced a half season on stock springs and looking back I wish I'd upgraded sooner. I purchased my springs from racetech. I went with the .54 front and 6.4 rear and my sag came out perfect. Make sure when you order mention you're a TT member and you'll get a pretty good discount.
For your weight you're gonna need a revalve though.
I tried it with just a spring change and while it's better than stock it's still not stiff'll still bottom pretty hard on big jumps
And it will rebound way too fast with the stiffer springs.....
I ended up changing my shock valving and it was good to go after the first change but I'm still working on getting the forks dialed in.

  • j.rush337

Posted March 03, 2014 - 07:00 PM


Mam these posts are really helpful thanks guys.

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