Trans gear ratios (info needed)

I'm looking for some info on transmission gears. I have a '99 YZ250 that I'm considering making a wide ratio. I know the '99 YZ 250 uses the same trans as the YZ 400. I want to see what gears would be required to make mine a WR. I'm not sure if the WR426 gears are different that the WR400. Any year WR400 should be the same.

The info I'm looking for is in Chapter 2 General Specifications. My YZ ratios are as follows:

1st 27/14 (1.929)

2nd 25/16 (1.563)

3rd 23/18 (1.278)

4th 24/22 (1.091)

5th 20/21 (0.952)

Thanks for any and all help

[ November 15, 2001: Message edited by: YZ Abuser ]

99WR400F

1st 29/12(2.416)

2nd 26/15(1.733)

3rd 21/16(1.312)

4th 21/20(1.050)

5th 21/25(0.840)

Hope this helps. :)

Thanks! I was hoping every damn gear set wouldn't need to be replaced! This might turn out to be too spendy for an extra bike.

Anybody out there with '98 and '00 WRs? Are they the same as Jekel's '99?

The 98 WR is the same as a 99 and I'm pretty sure the 00-02 did not change. You should also consider the primary drive ratio when attempting this mod. The 400's are running 2.952. Good luck.

00 WR ratio's are also the same.

Originally posted by scott h:

You should also consider the primary drive ratio when attempting this mod. The 400's are running 2.952. Good luck.

Yep, you are right about that. I'm not sure I'll tackle this project on this bike. It's about $450 worth of parts if I do all 5 gears.

I have to see if I can mix some gears without causing too big(or small) of gaps in the trans. Such as 3rd, 4th and 5th WR gears. I think that would be livable. However, it may make the 2-3 jump pretty small. That's probably the only way I could justify it to my wallet. :)

I can accomplish most of the same thing to my 250F for around $150 in parts. I can keep my 1st, 2nd and 5th gears. I use the YZ 5th as WR 4th and just buy the WR 3rd and 5th gear sets.

[ November 21, 2001: Message edited by: YZ Abuser ]

Or you could sell a part of your "fleet" of bikes to pay for it...or replace one or more of then with a nice, blue '02 WR426... :)

Funny! Not sure how many of you out there are like this...my buddy was at one time...5 freekin' bikes in his garage at one time...and when I went to the dealership to buy my new '01 WR426, he had to get one too!!

Maybe one day when I'm not spending $5M on baby formula and diapers, I'll be able to afford multiple bikes...then again, I suppose I'll be paying for the 50 pairs of shoes that my daughter most assuredly "needs"... :D

LarryinCO...you and I are living parallel lives..I have the cutest 2yr old in the world and one of these days another bike may grace the same floor space as my 426...I'm thinking after she is done w/college..it will happen! LOL

Or you guys can sell off the children and buy new bikes......hmmmmmm :)

Originally posted by LarryCO:

Or you could sell a part of your "fleet" of bikes to pay for it...or replace one or more of then with a nice, blue '02 WR426... :)

If the WR426 wasn't so big and heavy I might have one. That's why I went with the 250F. As I've gotten older I've found I go faster and longer with the smaller bikes. More fun too.

Now don't start ragging on me guys. I've owned 4 big bores in the past. Both 2 and 4 stroke.

YZ abuser

have a look at the third gear ratio's. nearly identical.

the transmission shafts I THINK come with the third gear forged in. if not and whichever, i don't think you need to change third gear.

all you need to do is buy the first, second, fourth and fifth gear's. i once checked it out at $238 or near.

Taffy

Taffy

It looks like the 1st gear pinion is on the main shaft. There are pinions for the rest of the gears listed, as well as wheels. I was looking at www.partsfish.com

After looking at this a little closer I think I could get by with adding only the 4th and 5th gear sets. Like you said, 3rd is pretty close. The jump from 3-4 would be ever so slightly larger. Larger than the YZ 3-4 gap, but smaller than the WR 3-4 gap (exactly half :) ) Sounds like a pretty easy way to get the top speed I need on occasion. Cheaper than a new KTM 250EXC, but not as effective. :D

That would be about $160 in gears. Probably another $40 in thrust washers and "E" clips. I'm planning a similar surgery to my 250F. If that doesn't pan out as well as I think it will I may go this route.

[ November 21, 2001: Message edited by: YZ Abuser ]

Taffy

What is Taffy Timed cams? also, did you ever try JD's "F" needle and what did you find?

YZ Abuser,

Just got your message, I don’t check my mail that often. I’m betting you will see this in lieu of an email message, I have a fractured wrist on my mouse hand and am too lazy to find your address.

I don’t have a 250, F or otherwise, so I don’t know if this applies…

To answer your question I did not need any special tools to split the cases on my ’00 YZF. On one occasion I did need to pry them apart but they were in a bind because a shift fork was wedged underneath the crank :)

I did need to make a puller to R&R the crank though, and you will need a press should you elect to replace any bearings.

I assume you would only need the gears to accomplish this swap, both “pinion” & “wheel” gears for each ratio for the bigger bike but either 250 may be different, although I imagine the 250 smoker gearbox is similar to the 400/426, since the gears themselves are.

I have considered putting WR 4th & 5th gears only in my YZ (I’m showing the WR 3rd gear is 3% shorter, WR 4th is ~4% taller, 5th 12%). A good way to model what this would be like is to compare the gear to gear jump before and after.

Starting w/ first to second jump here is what your smoker 250 would be like:

Stock

19%

18%

15%

13%

W/ WR 4th & 5th :

19%

18%

18%

20%

You would be almost 12% taller in fifth, keep in mind if you go from 14/49 overall to 14/51, for example, you take back 4% of that.

Taffy timing refers to his use of cam wheels from Falicon that enable you to degree the cams to different timing. Taffy found it strange that the exhaust cam timing difference WR to YZ amounts to exactly one gear tooth and suspected a compromise was afoot. He got somewhere in between that difference, and changed the intake timing as well, and liked it so much he is always wondering why more folks haven’t tried this. The factory team also changes the cam timing on Ferry’s bike, so IMO he is on to something.

Hope this helps.

burt@123mail.net is my email and you are welcome to use it.

[ November 21, 2001: Message edited by: Hick ]

I should qualify that post in two areas:

1) You may not need to press in new bearings into an old case, but I had hell putting new bearings in new cases, despite freezing the bearings and heating the cases w/ my torch, and I have a 20 ton press.

2) 250F vs WR250F ratios are, I think, totally different than the bigger bikes (400Fs & 250 smokers).

[ November 21, 2001: Message edited by: Hick ]

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now