Terrible motor swap idea kz440

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Re: Terrible motor swap idea kz440

21 Jan 2026 13:58
#920844



 
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
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Re: Terrible motor swap idea kz440

02 Feb 2026 06:54
#921136
Just an update: I've been hesitating moving forward with fixing the engine since I dont have a title but I've got that mostly figured out now so I'm ready to move forward with the build! I think step 1 will be getting that piston kit from cruzin image. I also want to split the case to take a look at the bearings and general condition but I cant take that clutch hub nut off. It's a real bugger. Does anyone know how?
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

02 Feb 2026 08:03
#921137
bound wrote:
I also want to split the case to take a look at the bearings and general condition but I cant take that clutch hub nut off. It's a real bugger. Does anyone know how?
 
Clutch basket holding tool and electric impact gun.
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike

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Re: Terrible motor swap idea kz440

02 Feb 2026 08:26
#921139
bound wrote:
Just an update: I've been hesitating moving forward with fixing the engine since I dont have a title but I've got that mostly figured out now so I'm ready to move forward with the build! I think step 1 will be getting that piston kit from cruzin image. I also want to split the case to take a look at the bearings and general condition but I cant take that clutch hub nut off. It's a real bugger. Does anyone know how?
Given that Cruzin Image say they don't fit and the fact that the head and cams are different on the later motor, I assume you are buying with your eyes open to the fact you may have a "matching set" of four ashtrays !!! does nobody do oversized pistons that are right for your motor ?
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca

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Re: Terrible motor swap idea kz440

02 Feb 2026 08:54 - 02 Feb 2026 09:00
#921141
The only one I've found are wiseco but those are way out of my budget for my motor. I believe that if the head doesn't work cause of either interference or high compression ill get the earlier head. I believe that those pistons will work since in the picture they have the same shape as my pistons although I don't know why. 

Another thing to mention is that the wiseco pistons work for all gpz550s im pretty sure. with that said, wiseco pistons are completely different. 
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig
Last edit: 02 Feb 2026 09:00 by bound. Reason: I forgot to mention something
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Re: Terrible motor swap idea kz440

02 Feb 2026 10:55
#921147
Do you know of any specific tools that have worked for others?
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

04 Feb 2026 15:48
#921225
Okay so I found out something pretty cool, just not cool for me
[img
. I'm pretty sure that those cruzin image pistons won't work unless i get the camshaft for the kz550h model. The reason seems to be that the zx550a cams are slotted differently for the sprockets and on top of more lift and duration that the earlier pistons werent designed for, I'd have issues with clearance. The later gpz pistons had a higher dome but deeper pockets to maintain compression and clearance that the early gpz did not have. There is a thread on here somewhere that goes pretty deep into it, I'm pretty sure its called 'gpz550 cams in a kz550 or zr550?'. It's an interesting read.
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

04 Feb 2026 17:02
#921226
bound wrote:
Do you know of any specific tools that have worked for others?
All the KZ/GPZ four cylinder bikes use the same clutch plates so any clutch hub tool for those will fit that basket (650/750/900/1000/1100)

I made my own tool out of a steel clutch plate in 1985 before they were commonly available.

 


 
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
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Re: Terrible motor swap idea kz440

05 Feb 2026 00:23
#921230
bound wrote:
Okay so I found out something pretty cool, just not cool for me
[img
. I'm pretty sure that those cruzin image pistons won't work unless i get the camshaft for the kz550h model. The reason seems to be that the zx550a cams are slotted differently for the sprockets and on top of more lift and duration that the earlier pistons werent designed for, I'd have issues with clearance. The later gpz pistons had a higher dome but deeper pockets to maintain compression and clearance that the early gpz did not have. There is a thread on here somewhere that goes pretty deep into it, I'm pretty sure its called 'gpz550 cams in a kz550 or zr550?'. It's an interesting read.
I think that given you are on a limited budget and the rest of the bike is going to need a lot of spend you might want to consider looking for a decent used block and pistons then hone and fit new rings (just my opinion)
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca
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Re: Terrible motor swap idea kz440

06 Feb 2026 11:52 - 06 Feb 2026 11:54
#921278
 you might want to consider looking for a decent used block and pistons then hone and fit new rings (just my opinion)

I wish that was feasible but there are effectively no used late gpz550 engine parts available on ebay so that puts me in quite a predicament... unless you guys find some for a reasonable price. The only other thing I saw someone do was use a different sprockets from his zr550 on the intake cam to guarantee clearance and it worked out for them. I read that from the thread that I mentioned earlier.
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig
Last edit: 06 Feb 2026 11:54 by bound. Reason: fixed some bad writing

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Re: Terrible motor swap idea kz440

06 Feb 2026 13:25
#921280
I hope you take my comments in the constructive manner intended. I think you may be getting “ the wrong end of the stick” I don’t see how a different sprocket can increase clearance!!!!!
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca

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Re: Terrible motor swap idea kz440

06 Feb 2026 14:21
#921285
Sorry if you took that the wrong way. Im just trying to weigh my options and I'm going to you guys for your opinion and your knowledge. If my thoughts are incoherent its probably because I have a lot on my mind at the moment 
[img
.  I did not explain myself about the cams nearly well enough, but if you read this you'll probably get a better explanation than I can give:  kzrider.com/forum/2-engine/607394-gpz-55...50-or-zr550?start=96  
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig
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