YZ250 spring rates

[avlehtine]

Hi,

I'm 95 kg (about 220lbs.) and ride a -00 YZ250. I'm no pro but it sure feels fast when I ride.

My problem is that I can't seem to set the bike up so that it doesn't bottom out (marks inside rear fender). I have the low-speed compression at 7 clicks (default 7) out and hi-speed at 1/2 a turn(default 2/6 turns). The defaults are different in Europe than in the US, don't know if the internals differ or if it's because of the different spring or general rider preferences.

The spring is 5.0 unequal pitch (I suppose this means variable rate or progressive=the same thing as far as I understand). It has two black dots near the bottom.

It bottoms out in really sharp whoops when I happen to slam the rear end into the face of one of the whoops. I have bottomed it in jumps too. Marks on fender plus I see it is at least pretty nearly bottoming on video.
http://personal.inet.fi/luonto/the.man/videot.html

I have the sag like this:
on stand: 605 mm.
on ground: 585-590 mm., depending on how it bounces up
me on the bike: 490-500 mm, depending on where I sit. 500 practically on the tank, 490 near rear fender but still on the seat.

Any idea what spring rate I should go for in the rear and if I should use progressive or straight rate? The fork is still at factory settings, should I change the fork springs too or add washers for more preload?

I'd be grateful for any insight into this matter.

 

[avlehtine]

Oh yeah, I did go to MXtechs calculator, and it says I should have a 4.995 rate spring. Well, I already have a 5.0, but it's variable rate so I think that (variable/not) affects what spring rate I should use.

I didn't run out and just get a 5.0 non-variable rate spring since I would really like to get it right the first time. I do have the resources to buy and try these, but I'm not exactly sitting on a pile of cash.

 

[Jeff Howe]

Here's my experience with the 00YZ 250. I presently weigh about 208lbs. For springs I run a 5.4kg shock and .44kg fork springs. I was on the verge of wearing a hole in my fender with a 5.2kg shock spring when I was weighing in at 200lbs.

You could try a 5.2, but I recommend the 5.4kg spring in the rear. Heck, if I was 220 I might try the 5.6kg just to see how it goes. You would be wise to go no less than 5.4 at this point though.

Another deal is the KYB B/O bumper is too friggin' soft. Get a HD bumper too! >44kg fork springs might be OK for you.

I can tell you that 5.0 is way too soft for you on that bike.

 

[avlehtine]

Thanks for the reply. You are talking about straight rate springs, right? I will probably go with the 5.4.

 

[Jeff Howe]

Yep, wouldn't touch a multi-rate spring.

Didn't know they spec'd them for YZ's overseas either. ODD!

 

[avlehtine]

My manual has the stock spring rates for US and European models, and they are different(a bunch of other stuff different also).

I think it's weird that the Euro manual has the info about the US model (4.8 straight-rate if I recall (manual at garage)) if the same manual doesn't come with the US bike.

Anyways, thanks for the info. Now I'll just have to locate a dealer. One dealer just said that everybody uses the same springs. Yeah right.

 

[Jeff Howe]

I think my manual might list Euro setting as well. I'll check it out. I haven't dug around much in the manual. I do know that in my 93 manual it lists all the Euro jetting specs. I remember seeing that. Spose' I better go blow the dust of the new manual and have a look in it. Somebody over there must deal Race Tech springs I would think. See if your dealer can get them for you.

 

[avlehtine]

On this topic:
The bike has .43 variable rate springs in the fork. I should probably get .44 (highest listed in the manual) straight-rate to go with a 5.4 straight-rate shock spring, right?

 

[Jeff Howe]

Yeah, you should get at least .44kg I think you would be better off with .46kg though. Why don't you e-mail MX-Tech and see what they can do about getting springs to you. He has them in stock and might be able to get them to you. Heck, I have them in stock but am not currently set up to ship over there. MX-Tech can probably do it for you.

 

[avlehtine]

As you can probably understand, I would rather get the stuff locally. Shipping charges and VAT (22%) tend to add up a whole bunch to the total, especially since dirt bike stuff is relatively inexpensive here (about the same prices as in the US).

I asked about good shops for this sort of stuff on a Finnish site and newsgroup and got four shops. I'll first see what they can come up with.

 

[Jeff Howe]

I figured as much. Local is good idea. Good luck with them springs.

 

[avlehtine]

The Finnish Yamaha importer gets me the springs. 5.4 in the rear and 0.45 in the forks (both straight-rate). Incidentally, these are the same springs that come stock on the YZ426F if my information is correct.

Any ideas on how I should go with the clickers when I install the springs? Just guesstimate a bit less compression damping and a bit more rebound damping?

 

[Jeff Howe]

You will just have to do a little tuning. That's half the fun brother.