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RPM crusing 15 May 2023 14:26 #884725

  • gordone
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6RPM and 90kmh/56mph

I norway most of the crusing happend between 80-90kmh.

When I’m crusing in 6RPM I feel I should have a 6th gear….

what do you think? Change ratio on gearing?
6rpm is fine?



 
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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RPM crusing 15 May 2023 15:44 #884729

  • MLMG
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I don't think it's right, you mean a KZ650?
1977 Kawasaki KZ1000 A1

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RPM crusing 15 May 2023 16:04 #884730

  • Nessism
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90 kph @ 6000 rpm doesn't sound right.  What sprockets do you have?

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RPM crusing 16 May 2023 00:07 #884737

  • Wookie58
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That would equate to 12k rpm at 180kmh(120mph) ????????? Might seem like a stupid question but are you sure the clutch isn't slipping ?

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RPM crusing 16 May 2023 01:33 #884739

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Hehe I think the RPM must be wrong then :)

the clutch is solid.

will find the ratio I have now.

When I’m crusing I don’t need to go down to 3th gear to find power when passing, just usr the throtle… so I was wondering if I go smaller rear I can have less RPM and then gear down to 3th when alot more power is needed.

its 750gpz with big bore 810cc high compresson. The carb is orginal 650 carbs…
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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RPM crusing 16 May 2023 02:59 #884741

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What size wheels are you running as this will also have an effect if smaller than stock 

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RPM crusing 16 May 2023 04:03 #884742

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It depends on the size of the engineand the transmission.  With standard gearing my Z1 will run around 4,000 rpm at 100 kph.  My wife's KZ550 used to run around 5,000 rpm at 100 kph, but that bike had six gears.  A small engine like a 250cc might run close to redline.
I have several restored bikes along with a 2006 Goldwing with a sidecar. My wife has a 2019 Suzuki DR 650 for on and off road.

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RPM crusing 16 May 2023 05:21 #884746

  • Injected
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6K at 90KPH is way too high, change your gearing.

I made so much more power than stock with my 831cc bike that I had to change the gearing. Your probably about 10 HP down from what I have, I had to change gearing because I could not shift out of first fast enough.

I run a 17T front and a 38T rear, at 90KPH it revs at 4,000.

If you have enough HP it will pull strong in any gear.


 
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Last edit: by Injected. Reason: pic

RPM crusing 16 May 2023 08:14 #884750

  • Wookie58
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This is a useful site to work out sprocket ratios for your set up and wheel size

Gearing Commander - Motorcycle Speed and Drive Train Calculator v7
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RPM crusing 16 May 2023 14:09 #884774

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Thank you all, will collect numbers and come back :) 
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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RPM crusing 16 May 2023 16:14 #884778

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The custom 17/38 final drive ratio gives you 104 kph @ 4250 rpm.

 
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RPM crusing 18 May 2023 01:12 #884827

  • gordone
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It was Norwegian national day here yesterday, so sorry for the delay :)

Front wheel - 100/90 - 19
Rear wheel - 130/90 - 16
Front sprocket - 16 tooth
Rear sprocket - 42 tooth

Haven`t checked these up against the webpage yet.
 
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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