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KZ440 cylinders on KZ400 engine 01 Nov 2023 02:46 #891180

  • Michel3007
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Hi all,

I am considering a modification on my KZ400H LTD. It would be to replace the 400 cylinder block with a 440 one. Finding a 440 complete engine in France is difficult hence this mod.
Other than the cylinder block, the pistons, rings and rods, is there anything else to consider ? I already have the 440 carbs.
I saw some posts on this topic but none were definitive.
Nebr_Rex, you seem knowledgeable on the topic, would love to here from you !

Cheers
KZ 750 H2 LTD 1981
GPZ750R1 1982

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KZ440 cylinders on KZ400 engine 02 Nov 2023 21:03 #891244

  • Nebr_Rex
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If it is the same style head maybe. Never messed with the late 400s ( except for transmission parts), just the early style 400s and 440s.
From memory late 400s had the roller timing chain, 6 speed trans and kick start.
Things to watch, sleeves fitting into the upper case half and timing chain guides and tensioner might be a little different.
Other than that everything will swap over. The heads and the cam are the same.
Another option is to bore the block for 440 sleeves.


.

 
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 cylinders on KZ400 engine 04 Nov 2023 11:44 #891281

  • Michel3007
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Thank you for the reply. Yes the heads are the same, as far as I can tell the cylinder block with what’s within are the only changes. What do you think about the crankshaft ? The rods are longer on the 440 from what I read but is a change of the crankshaft necessary, given the added power ? Although I guess that a bored 400 cylinder reaches the 440 power so shouldn’t be a concern. 
KZ 750 H2 LTD 1981
GPZ750R1 1982

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KZ440 cylinders on KZ400 engine 04 Nov 2023 18:13 #891293

  • Nebr_Rex
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Where did you read the rods are longer?
I'm pretty sure they are all the same.
Just swap the cylinder block and pistons.


.
 
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 cylinders on KZ400 engine 05 Nov 2023 03:59 #891306

  • Michel3007
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Hi,
I actually read that on your dotheton topic... first page, you are saying that the 440 rods are longer.
But noted, I will try the swap then !

Cheers
KZ 750 H2 LTD 1981
GPZ750R1 1982

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KZ440 cylinders on KZ400 engine 05 Nov 2023 16:08 #891335

  • Nebr_Rex
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The late 400 rods will be the same as the 440s.
I need to look back at ' my notes '.
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 cylinders on KZ400 engine 06 Nov 2023 01:41 #891352

  • Michel3007
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Thank you ! If you happen to find in your notes the diametre of the crankcase cylinder opening for a KZ400 H, I would love it !
My engine is still in the bike and I use that as a daily rider so it's difficult for me to take everything apart just to take the measurement.
I would like to make sure of that before buying the cylinder block.
KZ 750 H2 LTD 1981
GPZ750R1 1982

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KZ440 cylinders on KZ400 engine 06 Nov 2023 11:26 #891369

  • Nessism
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Partzilla references the '78 and onward 400, and the 440 use the same rod PN.

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KZ440 cylinders on KZ400 engine 07 Nov 2023 23:51 #891449

  • Michel3007
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Thank you Ed, what does PN means ?

I contacted ebaysellers that had a KZ400 B crankcase for sale, as nobody is better at giving fast answers than willing sellers, and the crankcase cylinder holes for the KZ400B appear to have a diameter of 76,2mm. As for the 440 cylinder sleeve OD, it is 73,6mm from what the German sellers tells me. So I went ahead and bought it and will report once installed, to let you know about the completed swap.

As always, thank you to those who took the time to answer,

Cheers,
KZ 750 H2 LTD 1981
GPZ750R1 1982

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KZ440 cylinders on KZ400 engine 15 Dec 2023 01:39 #892749

  • Michel3007
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Hi all,

Hope everyone is fine coming into the festive period.

Coming back to this topic to confirm that a kz440 cylinder block fits on a kz400h crankcase (which is the same as the 400B so should fit on these engines too) ! There is enough room for the cylinders. All I did was use a kz440 gasket set for the cylinder block, 440 pistons and rings. I also run 440 keihin cv36 carbs, with original airbox. The bike runs perfect. I will report once I have driven it for a longer period, didn’t have much time.

One question for you electricians out there, I had a problem with my stator wires (they were original and in a bad state so had to cut them off inside the case) which impacted my charging circuit. To repair, I used bullet connectors  inside the alternator case, covered with heat shrink tube. So far it seems to work but will it be ok in the long run ? Will the oil eventually lead to this repair to fail ?

Cheers,
KZ 750 H2 LTD 1981
GPZ750R1 1982

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KZ440 cylinders on KZ400 engine 15 Dec 2023 02:42 #892750

  • Wookie58
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Hi all,

Hope everyone is fine coming into the festive period.

Coming back to this topic to confirm that a kz440 cylinder block fits on a kz400h crankcase (which is the same as the 400B so should fit on these engines too) ! There is enough room for the cylinders. All I did was use a kz440 gasket set for the cylinder block, 440 pistons and rings. I also run 440 keihin cv36 carbs, with original airbox. The bike runs perfect. I will report once I have driven it for a longer period, didn’t have much time.

One question for you electricians out there, I had a problem with my stator wires (they were original and in a bad state so had to cut them off inside the case) which impacted my charging circuit. To repair, I used bullet connectors  inside the alternator case, covered with heat shrink tube. So far it seems to work but will it be ok in the long run ? Will the oil eventually lead to this repair to fail ?

Cheers,
I would suggest using "heat resistant" sleeving which is available in a range of sizes (same as the yellow cover fitted by factory) you can then use conventional heat shrink at the ends to seal. As it's not constantly immersed in oil I think you will be fine.



 
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KZ440 cylinders on KZ400 engine 15 Dec 2023 04:23 #892755

  • Nerdy
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Thank you Ed, what does PN means ?
 
 PN = part number

Partzilla.com is very useful for finding parts and part numbers. They will also tell you if a part is used on other models, which is helpful.
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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