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KZ440 08 May 2019 14:39 #803533

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Hey y’all, recently I picked up an early 1980s KZ440, I had heard about big bore kits to increase power and get the displacement somewhere in the 600s can anyone point me in the direction I need for a big bore kit or something? I’m new to chopping bikes and doing the work, so ANY guidance and recommendations/wisdom is welcome,
Thanks!

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KZ440 08 May 2019 18:43 #803553

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Where did you hear about 600cc?


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2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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KZ440 08 May 2019 19:00 #803555

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Nebr_Rex wrote: Where did you hear about 600cc?
.



I'm wondering that, too; it seems rather unlikely. That's a gain of 80cc on a cylinder that starts out as only 220cc.

AFAIK the KZ440 is not like the air-cooled VW engines where the case can be machined and larger barrels fitted to achieve noticeable increases in displacement.
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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KZ440 08 May 2019 19:22 #803557

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I just did some quick math and it would be nearly impossible.


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2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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KZ440 08 May 2019 19:54 #803561

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Here's a pic of a KZ440 that's bored all the way out. :laugh: Ed

1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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KZ440 08 May 2019 21:04 #803565

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Does anybody make bigger pistons for the 440?

Might be easier to install a 750 twin........

I wonder if a water cooled 500 twin would fit?
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

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Last edit: by TexasKZ.

KZ440 09 May 2019 14:19 #803606

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650ed wrote: Here's a pic of a KZ440 that's bored all the way out. :laugh: Ed


I though that was going to be a stack of washers. :laugh:
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
The following user(s) said Thank You: 650ed

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KZ440 11 May 2019 05:14 #803678

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So in relation to the 600(ish) size what my buddy was referring to putting a 650s pistons in. BUT that wouldn’t really do much cause the 650s piston is essentially the same size but what makes it a 650 is that it’s working across more cylinders than the 440.

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KZ440 11 May 2019 07:10 #803681

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_panc_ wrote: So in relation to the 600(ish) size what my buddy was referring to putting a 650s pistons in. BUT that wouldn’t really do much cause the 650s piston is essentially the same size but what makes it a 650 is that it’s working across more cylinders than the 440.


Where did you find that the KZ650 pistons were "essentially the same size" as those of the KZ440? I read that the KZ440 bore & stroke is 67.5 mm x 62.0 mm (2.7 x 2.4 inches) where as the KZ650 bore & stroke is 62 X 54mm (2.44 x 2.13 inches) (see links below). That's a pretty big difference. Think of it this way - if a 2 cylinder engine has 2 pistons and a displacement of about 440cc then a 4 cylinder engine with 4 of the same size pistons would have a displacement of about 880cc (that's 2 x 440).

Rather than rely too much on your buddy's opinions you would do well to do more research on your own. There is a lot of info available on the internet. Ed

bikez.com/motorcycles/kawasaki_z_440_ltd_1981.php

specs.kz650.info/TechSpecs.htm
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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KZ440 11 May 2019 08:31 #803684

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650ed wrote:

_panc_ wrote: So in relation to the 600(ish) size what my buddy was referring to putting a 650s pistons in. BUT that wouldn’t really do much cause the 650s piston is essentially the same size but what makes it a 650 is that it’s working across more cylinders than the 440.


Where did you find that the KZ650 pistons were "essentially the same size" as those of the KZ440? I read that the KZ440 bore & stroke is 67.5 mm x 62.0 mm (2.7 x 2.4 inches) where as the KZ650 bore & stroke is 62 X 54mm (2.44 x 2.13 inches) (see links below). That's a pretty big difference. Think of it this way - if a 2 cylinder engine has 2 pistons and a displacement of about 440cc then a 4 cylinder engine with 4 of the same size pistons would have a displacement of about 880cc (that's 2 x 440).

Rather than rely too much on your buddy's opinions you would do well to do more research on your own. There is a lot of info available on the internet. Ed

bikez.com/motorcycles/kawasaki_z_440_ltd_1981.php

.
specs.kz650.info/TechSpecs.htm


Actually 443.7cc X 2


.
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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KZ440 11 May 2019 08:40 #803685

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_panc_ wrote: So in relation to the 600(ish) size what my buddy was referring to putting a 650s pistons in. BUT that wouldn’t really do much cause the 650s piston is essentially the same size but what makes it a 650 is that it’s working across more cylinders than the 440...
.


Get your bike running right first. That will include valve lash, points and carbs.
Also brakes and suspension. A mishap on a motorcycle can be deadly.
Then when your ready I have more information about the KZ400/440 than most people can digest.


.
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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