Shaft drive gear ratio change

dxhemen
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07 Apr 2010 11:41 #359014 by dxhemen

Shaft drive gear ratio change was created by dxhemen

Hello, I am trying to gather info around the possibility of changing a gear ratio in my '83 Spectre 1100 SHAFT DRIVE.
I want to lower my freeway RPM for more comfy cruising.
At 75 mph it is in the high 3800-4000 range and too noisy.
I have the 130/90 tire also.
Would anyone have any ideas.
Thank you,
David H

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OKC_Kent
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08 Apr 2010 10:53 #359232 by OKC_Kent

Replied by OKC_Kent on topic Shaft drive gear ratio change

This would be a difficult change, and I don't really have an answer for you, sorry. But I didn't want you to think your question was being ignored, it's just something most of us (I think) would not attempt. I would think a machine shop would come in handy about now.

The easiest way would be to install a taller tire, but you won't gain much rpm drop. What is noisy, exactly? Engine noise, or exhaust?

Oklahoma City, OK
78 KZ650 B2 82,000+ miles

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Bluemeanie
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08 Apr 2010 20:54 #359397 by Bluemeanie

Replied by Bluemeanie on topic Shaft drive gear ratio change

I want to lower my freeway RPM for more comfy cruising.
At 75 mph it is in the high 3800-4000 range and too noisy.

I'm pretty sure there are no existing gear swaps for shaft drive. But I don't understand what is so noisy? My KZ650 is doing almost 6500 rpm at 75 and you want to talk buzzy!! I would think 3800-4000 rpm would be pretty nice on the freeway. I'd be happy with 5000 rpm at 70!

1980 KZ650F1, Bought new out the door for $2,162.98!

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Old Man Rock
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09 Apr 2010 06:04 #359431 by Old Man Rock

Replied by Old Man Rock on topic Shaft drive gear ratio change

"I would think 3800-4000 rpm would be pretty nice on the freeway"... No doubt!

In my setup, 5th gear at 75mph is spot on at 5500rpm...

Not complaining for my engine build with 15/37 sprocket combo is where I want my power band... Mid range!

Seems at cruising rpm yours has, should be just right. Shaft noise or exhaust?

OMR

1976 KZ900-A4
MTC 1075cc.
Camshafts: Kawi GPZ-1100 .375 lift
Head: P&P via Larry Cavanaugh
ZX636 suspension
MIKUNI, RS-34'S...
Kerker 4-1, 1.5" comp baffle.
Dyna-S E.I.
Earls 10 row Oil Cooler
Acewell 2802 Series Speedo/Tach
Innovate LC1 Wideband 02 AFR meter

Phoenix, Az

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T_Dub
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09 Apr 2010 06:10 #359436 by T_Dub

Replied by T_Dub on topic Shaft drive gear ratio change

Yeah I'm the same as Bluemeanie. The PO of my 650 has taller sprockets on, and I changed back to stock to get more acceleration. And now she revs very high on the highway. But my bike isn't for cruising so I don't care too much. 4000RPM is so smooth on these bike, can't see why you'd want to go lower.

1977 KZ650B1
-810cc
-Cavanaugh Racing Head
-Mikuni RS34's
-GPR Muffler

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otakar
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09 Apr 2010 07:11 - 09 Apr 2010 07:18 #359446 by otakar

Replied by otakar on topic Shaft drive gear ratio change

I went the other way around from most of you guys on my GPz1150. I feel that i have power to spare, and I wanted a good top end. When I converted to my 530 arrangement from the 630 I installed a 18t front and a 40t rear sprocket. In 5th gear and 4200rpm I am doing 79mph according to the GPS In fourth gear and 8200rpm I am doing 136mph. I am at 109mph at 5800rpm in 5th. This should give me a theoretical top end of 169mph at 9000rpm.

74 Z1-A stock
76 KZ-900 Totaly stock vice MAC pipe
77 KZ-1000A stock
78 Z1-R 100%MINT 500 original Mi.
78 Z1-R Yoshi 1103 kit stage 1 cams Yoshi pipe. Etc
79 KZ-1300 (1400)
80 KZ-1300
81 Scratch built GPz1150R
82 KZ1000

Last edit: 09 Apr 2010 07:18 by otakar.

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otakar
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09 Apr 2010 07:15 #359447 by otakar

Replied by otakar on topic Shaft drive gear ratio change

If you have not used this, try it it is great. All the info you need to plug in is in your Kawasaki manual, and on your rear tire.
www.gearingcommander.com/

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Old Man Rock
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09 Apr 2010 16:41 - 09 Apr 2010 16:42 #359565 by Old Man Rock

Replied by Old Man Rock on topic Shaft drive gear ratio change

Well not much he can do about it without some fairly in-depth internal gear changing...or am I wrong here....

Possibly with some different cams may be able to shift the rpm ranges a little but.... to what effect, probably not much...

Last edit: 09 Apr 2010 16:42 by Old Man Rock.

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PLUMMEN
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09 Apr 2010 17:10 - 09 Apr 2010 17:27 #359580 by PLUMMEN

Replied by PLUMMEN on topic Shaft drive gear ratio change

try a 140/90 tire.should give you roughly an extra 9mm on each side of rim basically raising gear ratio just a tad to lower rpms a little.
ill let the engineer types figure the exact numbers! :laugh:

Still recovering,some days are better than others.

Last edit: 09 Apr 2010 17:27 by PLUMMEN.

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KZ1100 Bully
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12 Apr 2010 11:11 - 13 Apr 2010 11:03 #360131 by KZ1100 Bully

Replied by KZ1100 Bully on topic Shaft drive gear ratio change

Hi, my 1983 kz1100 spectre runs 75mph is spot on at 4400rpm. You might want to double check that your gauge is working right. My bike is well maintained and running great. Has lots of power left at 75mph and does not seem like it is having a hard time maintaining that speed. Just the opposite it wants to go faster.

1983 Kawasaki KZ1100 Spectre D2

Last edit: 13 Apr 2010 11:03 by KZ1100 Bully.

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dxhemen
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14 Apr 2010 07:41 #360585 by dxhemen

Replied by dxhemen on topic Shaft drive gear ratio change

Thanks Kent,
I appreciate the info. It sounds like 3800-4000 isn't too bad by some other folks out there.
My main complaint was the buzz through the bars and grips, which are old hard originals. I should probably try some new ones.
Thanks again.
David H

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dxhemen
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14 Apr 2010 07:44 #360586 by dxhemen

Replied by dxhemen on topic Shaft drive gear ratio change

Thanks for the input.
I must be too used to autos at 2000 at 75mph.
It was really the handle bar buzz making me numb.
Some new grips may help.
Thanks again.
DH

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