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# L rear sprocket and rpm ?'s ... Mathematicians welcomed!

## 7 posts in this topic

OK, the L is geared at 15/45. I want to gear mine a bit higher by using a 42 or 43 rear sprocket.

You may need the 5th gear overall ratio to answer my questions, I think?

1) What RPM is the L cruzing at going 65 mph with stock gearing?

2) Same ? with 42 & 43 on.

3) If you can't answer either 1 or 2, can you tell me approx how much RPM drop I would have? With 42 around 500 RPM or so

16 tooth front, no one makes, just so you all know. It was hard enough to find a smaller rear one!

OH.......What the heck is the redline on these, 6-7000 or so ?

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if a xr600 sprocket is the same then this place has sizes to make your bike do 200mph check it out

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I don't have an L so I can't answer your question directly but I did find these links very helpful for sprocket choices vs RPM at different speeds.

try here

and also...

Bosshog

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Thnaks all.

Bosshog, think I know someone that can help me out with that sheet, I'd like to learn how it's done.

10-4 on that link drtlvr, I emailed them asking just that and if they say a 16 will fit, that would be great., otherwise a 42 rear is in order, maybe just a 43

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Let us know if the 16 tooth XR600 sprocket will fit. It would help me out as well.

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45:15 = 3:1

42:15 = 42/15 : 1 = 2.8:1

(3-2.8) / 3 *100 = 6.67% increase in top speed at redline.

(6.67% increase in speed for a "same gear-same RPM" comparison).

So if the stock geared XRL would do 100mph at redline, the new speed at redline would be:

100 * 0.0667 + 100 or 106.67

Dave

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Xr650l gearing vs rpm

formulated using the following data:

tire 686 mm dia = 2.155 circumfrence approx.86 inches

309 tr=40kmh

464 tire rotations per minute @60kmh = 1 to 1

619 tr=80kmh

773 rotations in 1.666km= 1 minute@100kmh

928 tr=120kmh

1082 tr=140kmh

1237 tr=160kmh

primary crank/clutch ratio=2.0294

X engine rpm = 1 tire rotation

@13/45 sprockets (3.46) 530 tire

gear ratio km 40 60 80 100 120 140 160

5th 5.97 1850 2775 3700 4625 5550 6450 7300 rpm@kmh

4th 7.021 2175 3250 4350 5425 6525 7600

3rd 8.78 2725 4075 5425 6775 8150

2nd 11.73 3625 5450 7250

1st 18.75 5800 8700

ratio is # engine rpm = 1 tire rotation

@14/45 sprockets (3.214) 530 tire

gear ratio km 40 60 80 100 120 140 160

5th 5.47=1TR = 1690 2550 3400 4225 5075 5900 6775 rpm@kmh

4th 6.52=1tr = 2025 3025 4025 5050 6050 7050

3rd 8.15=1tr = 2525 3775 5050 6300 7550

2nd 10.69=1tr = 3300 4960 6625

1st 17.34=1tr = 5350 8050

X engine rpm = 1 tire rotation

@15/45 sprockets (3.0) 530 tire

gear ratio km 40 60 80 100 120 140 160

5th 5.11=1TR = 1575 2400 3150 3950 4750 5550 6325 rpm@kmh

4th 6.088=1tr = 1900 2825 3775 4700 5650 6600

3rd 7.61=1tr = 2350 3525 4700 5900 7050

2nd 9.98=1tr = 3100 4625 6175 7700

1st 16.192=1tr = 5000 7500

X engine rpm = 1 tire rotation

@16/45 sprockets (2.81) 530 tire

gear ratio km 40 60 80 100 120 140 160 rpm@kmh

5th 4.847 1500 2250 3000 3750 4500 5250 6000

4th 5.70 1750 2650 3525 4400 5300 6150

3rd 7.12 2200 3300 4400 5500 6600

2nd 9.40 2900 4350 5825

1st 15.20 4700 7050

X engine rpm = 1 tire rotation

@13/48 sprockets (3.69) 530 tire

gear ratio km 40 60 80 100 120 140 160 rpm@kmh

5th 6.378 1975 2950 3950 4925 5925 6900 7885

4th 7.48 2300 3475 4625 5775 6950

3rd 9.35 2900 4350 5775 7225

2nd 12.34 3800 5725 7600

1st 19.97 6175

X engine rpm = 1 tire rotation

@14/48 sprockets (3.42) 530 tire

gear ratio km 40 60 80 100 120 140 160 rpm@kmh

5th 5.90 1850 2775 3700 4625 5550 6450 7300 rpm@kmh

4th 6.94 2175 3250 4350 5425 6525 7600

3rd 8.67 2675 4025 5375 6700 8150

2nd 11.45 3550 5300 7100

1st 18.53 5725

X engine rpm = 1 tire rotation

@15/48 sprockets (3.20) 530 tire

gear ratio km 40 60 80 100 120 140 160 rpm@kmh

5th 5.52 1700 2550 3400 4275 5125 5975 6825

4th 6.49 2000 3000 4000 5025 6025 7025

3rd 8.11 2500 3750 5000 6275 7525

2nd 10.71 3300 4975 6600 8275

1st 17.33 5350 8050

X engine rpm = 1 tire rotation

@16/48 sprockets (3.0) 530 tire

5th 5.11=1TR = 1575 2400 3150 3950 4750 5550 6325 rpm@kmh

4th 6.088=1tr = 1900 2825 3775 4700 5650 6600

3rd 7.61=1tr = 2350 3525 4700 5900 7050

2nd 9.98=1tr = 3100 4625 6175 7700

1st 16.192=1tr = 5000 7500