change tranny gears to make yz426 enduro friendly



35 replies to this topic
  • Scotti

Posted February 13, 2002 - 10:20 PM

#1

My son is about to pickup new 01 yz426. We ride
enduro and hairscrambles. I know 1st gear is going to be to tall for the tight stuff. I plan
to replace first gear with wr first, does any one
have experience with tranny changes? Will the jump from first to second be o.k? Should I change
5th also. any input would be greatly appreciated.

  • #1_Hit-man

Posted February 13, 2002 - 10:45 PM

#2

Originally posted by Scotti:
My son is about to pickup new 01 yz426. We ride
enduro and hairscrambles. I know 1st gear is going to be to tall for the tight stuff. I plan
to replace first gear with wr first, does any one
have experience with tranny changes? Will the jump from first to second be o.k? Should I change
5th also. any input would be greatly appreciated.

Why not try to go to a 51 rear sprocket(keep the front at 14) and get a 12oz flywheel weight? I think that should help alot on the tight stuff. That is what I will be doing to my 426. Should be a huge difference. :) ~Hitman~

  • Scotti

Posted February 13, 2002 - 12:33 PM

#3

hitman, I just don't think 3 0r 4 teeth will make
enough diff. If i change front counter and rear to
make slow gears work the top end will be out of wack. I am planning on the flywheel weight!

  • ben_suhard

Posted February 14, 2002 - 06:49 AM

#4

If he rides enduro, why not get a WR?

  • CAL

Posted February 14, 2002 - 08:35 AM

#5

If you're wanting wide ratio instead of close ratio...buy a WR. Transmission work is expensive! I just spent $750 on tranny work. It would be cheaper to buy a WR and make it look and feel like a YZ. Plus you'd get an 18" rear wheel.

On the other hand, I'm 99% trails on my YZ and with 13/49 gearing and the clickers way out, it's great. With the close ratio, it is hard to tell what gear I'm in sometimes, though. With the torque these things put out, it doesn't really matter anyway. :)

  • john.hilton@cape.k12.de.u

Posted February 14, 2002 - 08:57 AM

#6

I have 14/51 gearing on my 01' and a 12 oz. flywheel weight. It will still out pull a CR 250 on top, but it's great in the tight woods. Lots of low-end snap and plenty of torque.

John

  • Scotti

Posted February 14, 2002 - 09:18 AM

#7

We did't buy the WR because the yz was only
4800. brand spanking new. Plus my son prefers
the yz. Just ordered 1, 2, and 5th gears and gaskets for 260.00. But over on the wr side
i was told you can't swap individual gears!
Looking for someone who knows! Thanks.

  • Dan_YZF

Posted February 14, 2002 - 01:13 PM

#8

You "must" buy gear in pair: you want the WR 5th gear ratio, you'll have to buy the primary and secondary gear for the 5th gear and so for each gear

  • CAL

Posted February 14, 2002 - 03:10 PM

#9

Dan's right. There is a driving gear and a driven gear for each gear(1-5). You may have to replace the engagement dogs also. I'm not sure if the dogs are the same on a WR and YZ. The shafts, could be different as well. In my DRZ tranny I had to replace 2nd-4th gear. That meant 6 gears total. Also had to replace the engagement dogs between 3rd and 4th and a shift fork.

If you can't do the work yourself, plan on spending another $250(at least) for labor. My labor was $250 with me taking the engine(out of the frame) to the mechanic.

  • Boit

Posted February 14, 2002 - 09:16 PM

#10

Is it possible to swap gears of different diameters(teeth) randomly without machining the cases to relocate the centerline(shaft) of each gear? From my vastly limited knowledge of the transmission internals, I don't understand how 1st and 2nd gear can still mesh properly if one was to swap the 1st gear set for another set that has one less tooth. I thought that transmission gears were aligned so that everything meshed within specified tolerances. I just don't understand how internal gears can be changed without moving the centerline of the gear shafts such that the same mesh charateristics are maintained. Slap me hard and call me "Betty".

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  • CAL

Posted February 15, 2002 - 03:28 AM

#11

Originally posted by Boit:
Slap me hard and call me "Betty".


I'll slap you, Betty, but I think you're right. :) I don't see how it could work.

I'd sure hate to split my cases (on a brand new bike) and find out they wouldn't.

[ February 15, 2002: Message edited by: CAL ]

  • YZ400Court

Posted February 15, 2002 - 04:14 AM

#12

Originally posted by Boit:
Is it possible to swap gears of different diameters(teeth) randomly without machining the cases to relocate the centerline(shaft) of each gear? From my vastly limited knowledge of the transmission internals, I don't understand how 1st and 2nd gear can still mesh properly if one was to swap the 1st gear set for another set that has one less tooth.



That is why you change both the main shaft gear and the counter shaft gear as a set. Remove one tooth from one gear and add it to another (that is a generalization). The counter shaft on the YZ and WR were the same part number in 98. The main shaft and all the gear wheels were different. That said it would seem that the countershaft gears from a wr should fit in the countershaft of my YZ. The two questions I have are, will the WR main shaft gears fit the YZ main
shaft, and will the dogs between the gears on both sets still line up properly.

  • Boit

Posted February 15, 2002 - 09:46 PM

#13

YZCourt: Now that makes more sense. That explains the mesh and alignment question, so the next thing that comes mind is clearance within the cases. These transmissions are incredibly compact and the cases closely follow the contour of the gear sets. If you swap sets for larger diameter ones, they might rub against the cases. Would that be a fair concern or am I getting slapped and called "Betty" again?

[ February 15, 2002: Message edited by: Boit ]

  • YZ400Court

Posted February 16, 2002 - 07:50 PM

#14

Well Betty,
the cases on the YZ and WR are the same part number, so the WR gears should fit. I don't have all the gears that I originally ordered, but third definatlly will not work. The YZ gear has only 3 dogs on one side, the WR has 4. It would not be a problem if I were replacing 4th also as that is the gear the 3 or 4 dogs go into. Yesterday I decided to scrap the idea, then got looking at my third gear, and the dogs that mesh with fourth are pretty beat. So I ordered WR fourth also. Now only fifth remains, I'll see if it will work when I get the parts. I suspect first and second can be changed, it is third and fourth that screwed me up.

  • mike_dean

Posted February 18, 2002 - 02:11 AM

#15

I checked with Yamaha and the gears will fit, If I remember right 1st gear is part of the shaft. I was going to replace 4th and 5th gears for more top end, since the 3rd ratio is very close on both bikes, then you could change sprockets and get a lower 1st and still maintain the top speed of the YZ. Just replacing 4th and 5th is considerably cheaper and should keep a nice jump between gears. mike

  • YZ400Court

Posted February 18, 2002 - 03:05 AM

#16

Originally posted by mike dean:
I checked with Yamaha and the gears will fit, If I remember right 1st gear is part of the shaft. I was going to replace 4th and 5th gears for more top end, since the 3rd ratio is very close on both bikes, then you could change sprockets and get a lower 1st and still maintain the top speed of the YZ. Just replacing 4th and 5th is considerably cheaper and should keep a nice jump between gears. mike


I have a 98 YZ 400, and bought 98 WR gears 1, 2 & 3. 3 wont mesh with 4. Therefore changing 4 and 5 wont work. Ypu would have to change 3rd too. Read my last post above.

  • mike_dean

Posted February 18, 2002 - 10:30 PM

#17

YZ400court, that is good to know before I pull my engine apart, I guess I will need to get 3rd also. I have a 00 426 so it is probably the same. Yamaha told me they would interchange but must have meant that the shaft splines were the same and thought I was going to replace all the gears. thanks mike

  • SoCalWR426

Posted February 18, 2002 - 11:20 AM

#18

Don't slap me or call me Betty. But I have found that every time I have to use 1st gear (rarely) I am usualy screwed. 2nd seems to be my gear of choice for the tight stuff and rely on the flywheel and low 4-stroke grunt. I agree all the way with it is much easier and in the long run less costly to make a WR like a YZ than the other way around. If I recall my WR's 2nd gear is not too far off YZ's 1st. gear. That was an in the saddle guesstamate. So I think your best bet will be with a flywheel followed by sprocket changes.. But then again it's just my .02's worth, but your $$$$..

SoCal

  • YZ400Court

Posted February 18, 2002 - 02:36 PM

#19

The 00 426 may be different. I think they changed the ratios from 98. I guess the only way to be sure is tear into it and see :)

  • Scotti

Posted February 18, 2002 - 03:14 PM

#20

After searching TT archives I found mant who have
changed tranny gears. You must replace shaft and
drive gear for first. for each remaining gear you
wish to change you will need to buy the dog gear





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