close ratio transmission

SARS · Derestricted Danger Joined: 01 Mar 2004 Karma :

Would anyone like to tell me each gear ratio (6-speed) inside the transmission system of NSR 125?

McJamweasel · BCF Junkie Joined: 22 Mar 2002 Karma :

Primary: 3.250 - 65/20

Gears; 1: 3.090 - 34/11
2: 2.000 - 30/15
3: 1.470 - 25/17
4: 1.210 - 23/19
5: 1.043 - 24/23
6: 0.916 - 22/24

Final: 2.692 - 35/13
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SARS · Derestricted Danger Joined: 01 Mar 2004 Karma :

Thanks,mcjamweasel...

Mattastic · Trackday Trickster Joined: 03 Aug 2003 Karma :

Can someone explain what the ratio's mean please?
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

The ratio that one gear turns compared to the one it attaches to.

For example the gear on the crankshaft has 20 teeth and the one on the clutch basket (this is the primary drive) has 65 teeth. Therefore for every 1000 revolutions of the crank the clutch turns 1000 * (20/65), so 307 times. Then in 6th gear those 307 turns become 307 * (24/22), so 335 turns of the output shaft in the gearbox. Those 335 turns of the output shaft turn the front sprocket which drives the rear sprocket via the chain, and those 335 turns become 335 * (13/35), or 124 turns of the rear wheel.

All the best

Keith
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