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changing sprockets 81 KZ440

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11 Jul 2022 08:11 #870189 by Grinderman
changing sprockets 81 KZ440 was created by Grinderman
Just bought a 1981 KZ440 LTD, and would like to lower the RPM at hiway speed. does anybody have any thoughts ? thanks.

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11 Jul 2022 11:57 #870202 by Wookie58
Replied by Wookie58 on topic changing sprockets 81 KZ440
Gearing it up will reduce the highway RPM but it will also have a detrimental effect on acceleration, everything is a compromise you just need to decide which is more important for you

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11 Jul 2022 16:06 #870214 by Irish Yobbo
Replied by Irish Yobbo on topic changing sprockets 81 KZ440
I've done this on my KZ750, but only a small change. Changing your sprocket ratio (larger at the front or smaller at the back) will do this for you. Why do you want to lower your highway RPMs? If your engine feels a bit 'buzzy' this may fix it (I believe you have a 6-speed, so could drop back to 5th if you need that extra power). Fuel economy won't necessarily improve - these engines are designed to run at higher RPM and have a decent amount of valve overlap and are inefficient at lower RPM (the i4s in particular). And as wookie noted, changing your sprocket ratio will change across all gears.

1981 KZ750 LTD

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11 Jul 2022 16:16 #870215 by Nessism
Replied by Nessism on topic changing sprockets 81 KZ440
Moving up one tooth on the front sprocket makes a noticeable change and is cheap.  Make sure you have clearance at the output shaft, and realize that chain lengthening may be needed if your chain is currently on the short side.

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11 Jul 2022 17:28 #870218 by Nerdy
Replied by Nerdy on topic changing sprockets 81 KZ440

Just bought a 1981 KZ440 LTD, and would like to lower the RPM at hiway speed. does anybody have any thoughts ? thanks.
 

Before we get too far into the discussion, which LTD model do you have: a KZ440A (chain drive) or a KZ440D (belt drive)?

If you have chain drive, the suggestions made so far will work. Keep in mind that a countershaft adjustment of one tooth is equivalent to an opposite adjustment of 2-3 teeth on the rear sprocket. For example, going up one tooth on the front will give the same result as going down 2-3 teeth on the rear.

If you have the belt drive, you don't really have any easy options for changing the final gearing. In that case you can convert to chain drive and proceed as normal.

1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R

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16 Jul 2022 16:42 - 16 Jul 2022 16:44 #870477 by Sdaniels2010
Replied by Sdaniels2010 on topic changing sprockets 81 KZ440
I dropped 4 teeth on the rear sprocket...runs about 400-500 rpm lower between 60 & 70 mph & I really can't tell much difference in acceleration but this is a commuter bike mostly & never really wind the joker up anyway.  I had to remove 1 chain link.

1981 KZ440 A2 LTD
Last edit: 16 Jul 2022 16:44 by Sdaniels2010.

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