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stroker yz426

which gear box do most like? yz or wr?

11 posts in this topic

so i have almost finished my third stroker yz 426 (well not anymore but..) and i was thinkin about swaping some gears from the wr into the yz and then i thought well if im going to take some i guess ill replace all the gears from the wr, :worthy: granted i know that third and fourth are the same on both machines, but i havent ridin a wr with this engine so i dont know how low first is and how high fifth is

does anyone out there feel that the wr is tooo steep of a first gear? and well fifth is fine i only use fifth on sunday's or at the dunes so it doesnt matter too much if it drops a bit more into "overdrive" so to speak. all your input will be great valued :busted:

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really since when did they change, because last time i looked in my manuals they were the same, the wr use a different 1 2 5 gears

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2001 WR426:

  • 5BF-17131-20-00 GEAR, 3RD PINION (16T)
  • 5BF-17141-20-00 GEAR, 4TH PINION(20T)
  • 5BF-17231-00-00 GEAR, 3RD WHEEL (21T)
  • 5BF-17241-00-00 GEAR, 4TH WHEEL (21T)
  • Ratio in 3rd = 1.313:1
  • Ratio in 4th = 1.050:1

Source: Yamaha Parts manual

2001 YZ426F:

  • 5BE-17131-20-00 GEAR, 3RD PINION (18T)
  • 5BE-17141-30-00 GEAR, 4TH PINION (22T)
  • 5BE-17231-00-00 GEAR, 3RD WHEEL (23T)
  • 5JG-17241-00-00 GEAR, 4TH WHEEL (24T)
  • Ratio in 3rd = 1.278:1
  • Ratio in 4th = 1.091:1

Source: Yamaha Parts manual and 2001 YZ426F(n) Owner's Service Manual

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I've been thinking of changing my '07 YZ450 to a WR gearbox.

Here are some calculations from a spreadsheet I got off of TT. I picked the sprockets to try to match first gear.

Works out to a top speed of 96mph for the YZ and 124 for the WR. That is at 11000 rpm.:busted:

EDIT: the columns don't line up but the last number in the row is the overal ratio in that gear.

YZ07

Primary Ratio 61 23 2.6522

Secondary Ratio 49 13 3.7692 Overall

1st Gear 27 14 1.9286 19.2793

2nd Gear 23 15 1.5333 15.3282

3rd Gear 23 18 1.2778 12.7735

4th Gear 24 22 1.0909 10.9054

5th Gear 20 21 0.9524 9.5206

WR07

Primary Ratio 61 23 2.6522

Secondary Ratio 45 15 3.0000 Overall

1st Gear 29 12 2.4167 19.2283

2nd Gear 26 15 1.7333 13.7913

3rd Gear 21 16 1.3125 10.4429

4th Gear 21 20 1.0500 8.3543

5th Gear 21 25 0.8400 6.6835

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Refigure your top speeds for 10K or 10.5. The bike will never pull 11 grand in 5th with that kind of gearing. Then reduce it by 5% for tire slip on pavement, or 10% (at least) on dirt.

As far as matching low gears, one of the advantages of the WR box is in having a low gear low enough to pick through a rocky wash yet still have a little leg at speed.

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The gear spacing would be more consistent if you used the whole WR trans. Otherwise, the jump from 2-3 will be a little larger than in the WR, 3-4 will be closer than any other in the trans, and the 4-5 gap will be larger than the WR, also.

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Refigure your top speeds for 10K or 10.5. The bike will never pull 11 grand in 5th with that kind of gearing. Then reduce it by 5% for tire slip on pavement, or 10% (at least) on dirt.

As far as matching low gears, one of the advantages of the WR box is in having a low gear low enough to pick through a rocky wash yet still have a little leg at speed.

I agree these calcs have no corrections for real world just a way to compare setups and differnt bike gear ratios.

Are you saying that it is possible to mix and match WR and YZ gearing without too much trouble?

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It depends. Within the 426 family, you can mix/match, and some have done it, but if you plot out the ratios, the spacing gets to be odd when you start doing that. I don't see a combination that I really like in it.

The trans parts can be mixed to some extent (exactly how much remains to be seen) on '06 and later YZ450's and the '07 and later WR, but the same caveats about ratio spacing apply.

The early 450's, '03-'05 YZ's and '03-'06 WR's are an all or nothing swap, since one is a four speed and the other a five. Nothing from one trans fits the other.

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