Ideal weight for stock 07'yz 250 springs.


15 replies to this topic
  • Sidd

Posted 20 May 2008 - 10:09 AM

#1

Anyone know off hand what the stock suspension is set up for as far as rider weight, without gear. I guess gear would add about 20 lbs. Thank you.

Sidd

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  • ThumperKid250F

Posted 20 May 2008 - 10:52 AM

#2

not sure but i would like to know my self..

  • SpDyKen

Posted 20 May 2008 - 11:28 AM

#3

Note that you need to specify what type of riding you are setting up the suspension for; eg. MX, desert, GNCC, enduro, etc.

See http://www.mx-tech.c...pring_generator to enter the data you are interested getting results for.

Do note that the stock rates given here are for the '08 YZ250. The '06 & '07 stock spring rates are 0.42 kg/mm & 4.8 kg/mm, according to the Yamaha Parts information.

So, for enduro type riding, the stock suspension is just right for someone who weighs 195 lbs., with their gear on.

I'm going to ask Jeremy if we also need to factor in all of the extra 'bike protection' we tend to bolt up to a bike ridden in the woods, etc. I'm talking to him soon, anyway.

  • bikedude127

Posted 20 May 2008 - 12:31 PM

#4

My manual for my 07 YZ250 2t calls for .429 (.430) in the front and a 4.9 rear :thumbsup:

I weigh 150, maybe 160 or so with gear.. I went to .440 in the front and am investing in a 5.0 or 5.1 for the rear.. Primarily for desert and woods.. Very little moto....

  • techmc

Posted 20 May 2008 - 12:45 PM

#5

I weigh 150, maybe 160 or so with gear.. I went to .440 in the front and am investing in a 5.0 or 5.1 for the rear.. Primarily for desert and woods.. Very little moto.... :thumbsup: :rolleyes: :rolleyes: I weigh 169 with gear on and couldn't handle a heavier spring on the front, it's already low oil level inside fork and outter leg and it seems too stiff. The back i think is 4.8k and it is perfect, any heavier and wouldn't like it. This is only for MX tracks, if I did woods I'd probably go down on spring rate and adjust dampening. May go 5.0 in rear for desert but I'd have to see compared to 4.8. Am I missing something ???? I thought with your weight and No MX racing, you'd want to go down or at least stay stock, and play with dampening???:crazy:


Techmc

  • bikedude127

Posted 20 May 2008 - 01:24 PM

#6

Tech, me and my tuner have been experimenting with stiffer springs and uber soft valving with very good results.. The stiffer springshelp carry the bike in the top of the travel where the action is very plush, then they also seem to help control bottoming, along with adding oil to the fork.. I should also mention we've completely removed the mid valve in the fork to further exaggerate the soft feel in the front..

  • techmc

Posted 20 May 2008 - 01:45 PM

#7

Yea, thats right I had heard on here about you doing that, but I didn't know if it was working for you. I definately will look into removing mid valving from front. But I'm happy with rear right now. Maybe it can work for just MX!

Techmc

  • RCannon

Posted 20 May 2008 - 02:03 PM

#8

Obviously some factories set spring rates a little different. Most mx bikes are supplied for an intermediate rider. Weight is 125-140 for a 125, 250 is near 165-175 and closer to 180 for the open bikes like the older kx 500 or cr 500. Yamaha went stiffer in the past year and it is close to being set up correctly for the listed weights with gear. Boots weigh damn near 10 lbs.

As SpDyKen said, the type of riding is going to play a big part in how stiff you want the springs. A properly sprung for Motocross bike can beat the living hell out of you on an all day ride.

  • bikedude127

Posted 20 May 2008 - 02:34 PM

#9

Yea, thats right I had heard on here about you doing that, but I didn't know if it was working for you. I definately will look into removing mid valving from front. But I'm happy with rear right now. Maybe it can work for just MX!

Techmc


Im very, VERY happy with the fork right now and we are only on our second internal change.. :rolleyes: Still have a couple ideas I want to discuss with Mitch, my tuner..

The shock is unfortunately being out performed by the fork now.. The fork action is very compliant with rolling and square edge bumps where the shock feels pretty too slow and a little harsh.. But as I soften up comp and speed up rebound to compliment the fork I have bottoming and deflection issues.. Our idea is that hopefully the stiffer spring and softer valving in rear will help carry the rear end higher and defend bottoming while remaining plush.. Time will tell.. :thumbsup:

BTW Im also running 18" rear and 20" front.. Really takes the edge off :rolleyes:

  • SpDyKen

Posted 20 May 2008 - 03:11 PM

#10

My manual for my 07 YZ250 2t calls for .429 (.430) in the front and a 4.9 rear :thumbsup:

I weigh 150, maybe 160 or so with gear.. I went to .440 in the front and am investing in a 5.0 or 5.1 for the rear.. Primarily for desert and woods.. Very little moto....

This is confusing me. I pulled this from Yamaha's website - 20 1P8-23141-M1-00 SPRING, FRONT FORK (K=4.2N/ ; and, 9 1C3-22212-20-00 SPRING (K=48N/MM) , at: http://www.yamaha-mo...parts/home.aspx

I just checked my '06 YZ250 manuals; they say that the 4.9 is the standard spring, as well. I'd sure like to know what the truth is. I'll be talking to Jeremy tomorrow; I'll be sure to ask him about this.

It makes it hard to buy take-off springs, if you cannot trust the parts listings for the different YZ's.

Anyone out there know more about this issue?

  • RCannon

Posted 20 May 2008 - 03:30 PM

#11

I remember them talking abotu the ti spring when it was released. The word was that is was sort of progressive and not rated accurately. Still, I have never had problems with mine.

The rear spring went from a 4.8 in 2005 to a 4.9 in 2006. The fork spring got slightly softer in the same time period. 2005 was a .43 to a .42.

The problem the tolerances of the spring can be off quite a bit from the rating. If MX tech or Race tech tested the oem springs they might be off quite a bit from the service manual.

  • Sidd

Posted 20 May 2008 - 04:24 PM

#12

My rider will be using it for outdoor motocross and weights between 150 and 155 without gear. I couldn't believe all the posts that showed up:applause:

Sidd

  • bikedude127

Posted 21 May 2008 - 07:15 AM

#13

Thats odd.. I could have sworn my 05 had .440 fronts?? :thumbsup:

Do I have a mis printed Yamaha manual?? :rolleyes:

  • adam728

Posted 21 May 2008 - 10:36 AM

#14

The Yamaha service manual for my 05 lists

Front - 0.438
Rear - 4.9

  • RCannon

Posted 21 May 2008 - 02:45 PM

#15

I threw my years big time...I will correct things!

  • RCannon

Posted 21 May 2008 - 02:45 PM

#16

Do I have a mis printed Yamaha manual?? :thumbsup:[/QUOTE]

No, just a Mod who should not type with his contact lenses out.





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