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Old 01-07-2013, 05:58 AM   #51260
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Joined: Aug 2011
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The following information is combined Tech form different threads and my own head...

This information can be used to build a wide ratio or close ratio gear box for all of your needs.

The primary and final gear ratios only effect the effective overall ratio. They don't change the transmission ratios You'll need to split the cases for that.

Stock gear ratios


Primary Reduction 2.188 (70/32)

1st Gear '83-84 is 13/32 (2.46)

1st gear '85-87 is 13/31 (2.38)

'85-'87 XR600R & XL600R

31/13 2.38
28/17 1.65
25/20 1.25
23/23 1.00
21/25 0.84

XR600R gear ratios

Primary reduction 2.188 (70/32)
Final reduction 3.429 (48/14)
1st: 2.385 (31/13)
2nd 1.647 (28/17)
3rd 1.250 (25/20)
4th 1.000 (23/23)
5th 0.840 (21/25)

XR650L Gear ratios

Primary Reduction: 2.029 (69/34)
Final Reduction: 3.0 (45/15)
1st: 2.66 (32/12)
2nd: 1.647 (28/17)
3rd: 1.250 (25/20)
4th: 1.00 (23/23)
5th: 0.84 (21/25)

NX650 US model

Primary Reduction: 2.029 (69/34)
Final Reduction: Varies
1st 2.66 (32/12)
2nd 1.75 (28/16)
3rd 1.25 (25/20)
4th 1.00 (23/23)
5th 0.84 (20/25)

NX650 Euro & FMX650 gear ratios

Primary Reduction: 2.029 (69/34)
Final Reduction: Varies
1st 2.66 (32/12)
2nd 1.75 (28/16)
3rd 1.25 (25/20)
4th 1.00 (23/23)
5th 0.80 (20/25)


31/13 2.38
28/18 1.55
24/20 1.20
23/23 1.00
21/24 0.875

Primary Reduction 2.029 (69/34)

Primary Reduction 2.188 (70/32)

Primary Reduction 2.029(69/34)

XR 5th gear 21/25

NX 5th gear 20/25

Try some combo's on for a while.

You can change the listed NX650 5th gear tooth count to the Euro spec.


I used that same chart and elaborated with different primary and final drive ratios back when I was trying to decide what gearing I wanted to run.


I am wanting to create a wide ratio gearing for my XR650L and trying to learn if there is a Honda OEM stock first gear from any Honda 650 engine that is compatible with the XR650L that is one tooth more than the XR650L stock 1st gear.

What I'm trying to do is get the ratio to something like 33/12 - 2.75 or 32/11 - 2.91. I'm researching if there exists a gear or gear pairing that will accomplish this.

Is there a compatible Honda 650 transmission that would drop into the XR650L transmission and give me the gearing ratio preferably close to a 32/11 - 2.91?

I have already obtained the 2nd and 5th gear listed on this thread.

My thought is if I am going to crack the case open then I might as well get all the gearing I want.

Any help would be greatly appreciated.

Gearbox Operation

The 1st gear is #4 on the parts fiche.


Here are a couple spreadsheets that show the differences in the 2nd and 5th gear swaps

XRL with stock gearing and stock 15T/45T sprockets

XRL with NX650 gearing but still with stock 15T/45T sprockets

XRL with NX650 gearing but still with 15T/48T sprockets

XRL with NX650 gearing with 14T/49T sprockets

Here is a link to the program above in case you want to plug some values in for yourself.


I only changed the 20T 5th gear to a 21T and I changed the 17T 2nd gear to a 16T. The gears are direct drop. You only have to change one gear where there is only one gear that is different in the pair as marked below. The gears on the NX650 have one tooth less that are in bold below. The reason why the the gears in bold below are direct drop in is because the actual teeth on the NX650 gears are thicker to compensate for the smaller gear diameter. I changed both and they are direct drop in trust me. Keep in mind that if you frig with the other gears you might have to change the pair (drive and driven) in order to change the ratio. If your going to change the ratio of any gears where both tooth count on both gears in the pair are different then you'll have to change the pair of gears.

------ NX650 ... XRL650
2nd--- 28/16 ... 28/17
5th--- 20/25 ... 21/25

I assume you mean there is no ratio higher than 2.66, if so than you are correct 2.66 is the highest ratio available but by putting a NX650 5th gear you can change the sprockets to raise the final ratio higher but keeping the final ratio in 5th gear reasonable for highway use.

The 2nd gear mod brings the ratio of the 2nd gear closer to that of the 1st gear and its a much smoother smoother transition between those gears. The 5th gear mod widens the gap between the 4th and 5th gear ratio. I did this mod because I wanted to be able to run 14T/49T sprockets for better offroad torque but at the same time be able to run this combination on the highway without the engine over-revving. The 2nd gear is available in the US or about $40 but the 5th gear can only be purchased in Europe. I got both gears off a complete used transmission I bought from a German seller on ebay for $175 shipped. Big big difference for anyone wanting to take on this mod but beware it does involve complete tearing your engine apart.

2nd 23421-MN9-010 available Honda USA ~40$
5th 23491-MW2-780 available Honda EU

@Virginian Notice the wider teeth on the 20 tooth counter shaft fifth gear is on the left, stock 21 tooth on the right. (props to flatfender for the pics on atvrider).

This chart will show how the ratios compare with other bikes.


New additions -- KLX250S, KTM690E

This list was getting too long, I've removed the 2-strokes, the trials bikes, and most of the bikes that were never sold as street legal. I have left the Honda XR650R on the list since it such a popular bike on this forum. You can find a more exhaustive list later in the thread.

The first number is the first gear ratio divided by the top gear ratio. The bigger the number, the wider the gear spread.

The number following the motorcycle name is what the actual overall low gear would be if gearing was raised until every motorcycle had the same ratio (5.05:1, or about what comes standard on a DR650 or KLR650) in high. Of course that caused all the first gear ratios to jump higher as well, so sorting by first gear, the lower the first gear ratio, the wider the overall gear spread.

Or put another way, if you replaced the sprockets on all these motorcycles so that they all had exactly the same gearing in high, this is how they would end up in first. The higher the number, the lower the gearing, and the wider the gear spread.

5.00 Montesa Cota 349 (6 speed) 25.25

4.97 Fantic 300 25.12

4.41 Yamaha TY250L 22.26

4.38 Yamaha DT175E (6 speed) 22.08

4.00 Honda TL250 (5 speed) 20.20

3.90 Yamaha XT225 (6 speed) 19.69

3.82 Montesa V75 Enduro (5 speed) 19.29

3.80 Hercules 250 (7 speed) 19.19

3.78 Honda CRF230L (6 speed) 19.12 (current widest ratio dual sport)

3.75 Suzuki DR125 (6 speed) 18.95

3.74 Can-Am 175 ASE 18.85

3.69 Montesa Enduro 360H (6 speed) 18.63

3.63 Kawasaki Sherpa 250 (6 speed) 18.30

3.54 Husqvarna 500XC 17.89

3.53 Suzuki RS175Z 17.85

3.53 Husqvarna 400WR 1984 17.82

3.53 Honda XR200R (6 speed) 17.81

3.52 Honda XR250L (6 speed) 17.69

3.47 Kawasaki KE125A5 (6 speed) 17.49

3.46 Yamaha XT250 2008 (5 speed) 17.50

3.45 Yamaha TW200 (5 speed) 17.43

3.45 Suzuki PE175D (6 speed) 17.42

3.40 Husqvarna TE610 (6 speed) 17.16

3.40 Honda XR200R 1984 17.16

3.40 Honda XR250R (6 speed) 17.16

3.36 Yamaha WR250R/WR250X (6-speed) 16.99

3.33 Honda NX/FMX650 (5speed) 16.77

3.32 Kawasaki KLR250 (6 speed) 16.76

3.29 Yamaha Tenere (5 speed) 16.61

3.27 BMW G650X (5 speed) 16.54

3.25 Pegaso 650 (5 speed) 16.41

3.19 Husqvarna 175XC 16.10

3.18 Kawasaki KDX200 (6 speed) 16.08

3.18 KTM 530 E/XC-R (6 speed) 16.07

3.18 Husaberg FE650E (6 speed) 16.07

3.18 Husaberg FE450/570 (6 speed) 16.07

3.18 Honda XR650L (5 speed) 16.07

3.15 Kawasaki KLX250 (6 speed) 15.91

3.14 Yamaha IT200 (6 speed) 15.88

3.14 Honda XR350R (6 speed) 15.86

3.13 BMW F650GS (5 speed) 15.79

3.06 KTM 640 Adventure (5 speed) 15.44

3.04 KTM 950 (6 speed) 15.37

3.03 Yamaha XT500G (5 speed) 15.29

3.03 Suzuki DR350 (6 speed) 15.28

3.01 KTM 520 E/XC (6 speed) 15.16

2.93 Suzuki DR650 (5 speed) 14.77

2.88 Yamaha WR450 (5 speed) 14.52

2.88 KTM 690 (6 speed) 14.51

2.86 Kawasaki KLR650, KLX650 (5 speed) 14.42

2.83 Honda XR600R (5speed) 14.26

2.82 Honda XR400 (5 speed) 14.27

2.80 BMW G450X (5 speed) 14.10

2.68 Kawasaki KLX450R (5 speed) 13.51

2.66 Honda XR650R (5 speed) 13.43

2.65 Suzuki DRZ400 (5 speed) 13.36

2.47 Aprilia RXV 550 (5 speed) 12.46

2.45 Husqvarna TE250 (6 speed) 12.40

2.21 Honda CR500R (5 speed) 11.17

Post up any tech or real world reports you have.

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MentalGuru screwed with this post 01-07-2013 at 06:07 AM
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