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'80 KZ650 sprocket ratios 14 Aug 2020 09:35 #832893

  • jekyllman
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Just wrapped up a year-long custom job on a 1980 KZ650 and took it on the freeway for the first time today. I replaced both sprockets with new ones per the manual specs. I have to admit, it feels like it's geared really low - I find myself hit 5th (final) gear when I'm on 45mph roads. Around here (Idaho) there are plenty of 80mph speed limit interstates and it really feels stressed at 70 even though it's still got plenty of power. Anybody feel the same way with these 650's?
1980 KZ650F1 - 9k miles (current cafe project, nearing completion)
1981 KZ305 CSR - 10k miles (didn't have the heart to customize this one, will stay original)

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'80 KZ650 sprocket ratios 14 Aug 2020 10:43 #832897

  • 650ed
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At 70 mph the KZ650 engine should be turning roughly 5250 rpm. If yours isn't there's a problem. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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'80 KZ650 sprocket ratios 14 Aug 2020 10:59 #832899

  • martin_csr
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The rpms can vary somewhat depending upon the sprockets. I would check the number of teeth to see if yours are stock are what.

My 81 KZ650-CSR can do 70 mph all day long, and speeds runs up to 85 mph & above are no problem. I've had several occasions when the battery & ignition coils caused the motorcycle to run poorly at speed. low electrolyte once, then a bad battery & bad coils another time.

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Last edit: by martin_csr.

'80 KZ650 sprocket ratios 14 Aug 2020 11:45 #832901

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I'll have to check and see on the RPM. The new tach I installed is digital so the reading is totally off. For what it's worth it SEEMS super high at 70mph. Like around 7k.

Current sprockets are what are listed in the manual so I can't imagine that's the issue. :dry: :dry: :dry:
1980 KZ650F1 - 9k miles (current cafe project, nearing completion)
1981 KZ305 CSR - 10k miles (didn't have the heart to customize this one, will stay original)

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'80 KZ650 sprocket ratios 14 Aug 2020 13:51 #832909

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If the sprockets are the correct sizes but the engine rpm is higher than normal maybe the clutch is slipping. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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'80 KZ650 sprocket ratios 14 Aug 2020 16:04 #832919

  • gd4now
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Here are to the best of my knowledge the stock sprocket numbers for the 650s.

B1 42/16
B2 42/16
B2A 42/16 2.63
B3 42/16
B4
C1 42/16
C2 42/16
C3 42/16
C4
D1 40/16
D1A 40/16 2.50
D2 41/16 2.56
D3
D4 33/13 2.538
E1 41/16
F1 42/16
F2 34/13 2.615
F3 34/13
F4 34/13
H1 33/13 2.538
H2 33/13
H3 33/13


the 42/16, 41/16 and 40/16 use a 530 chain
the 33/13 and 34/13 use a 630 chain
1977 KZ650 B1
Pods and Denco header


This is my Z

OLD KAW OWNERS SMILE ALOT

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