Terrible motor swap idea kz440

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Re: Terrible motor swap idea kz440

18 Jan 2026 12:23
#920747
Since i need new pistons, why not go 615cc? Right? Im on a tight budget so wiseco is not an option right now. I see these cruzin images pistons that seem to be well regarded on a budget but I'm wondering since this is a 1985 gpz550, it has 10:1 stock compression ratio. The heads and pistons are different for this bike compared to all other kz/gpz550s so I dont know how other pistons will affect this. Will 615cc pistons from cruzin images for the 1981-1983 gpz550 work well?
 
The Ebay Cruzin Image 615cc pistons look to be the same design as what you took out of that engine.

 

I believe the kit is just mislabeled as to what year it fits.
 
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

18 Jan 2026 13:11
#920749
That's so funny! I just took a screenshot of the pistons to ask if they have the same dome shape as mine.. I just sent a message to cruzin image to ask if those pistons will work on my gpz550.
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

18 Jan 2026 15:00
#920753
Cruzin image got back to me and said this: "Thank you for your question. Regarding the KZ550 PISTONS KIT, the pistons and rings are different between the 1981–1983 models and the 1984 and later models.
Therefore, the pistons kit that I sell does not fit the 1985 model.

Best regards,
Mitsuo" 

I understand how the pistons would be different but not the rings. Curious on what you guys think.
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

18 Jan 2026 17:52 - 18 Jan 2026 17:55
#920756
Cruzin image got back to me and said this: "Thank you for your question. Regarding the KZ550 PISTONS KIT, the pistons and rings are different between the 1981–1983 models and the 1984 and later models.
Therefore, the pistons kit that I sell does not fit the 1985 model.

Best regards,
Mitsuo" 

I understand how the pistons would be different but not the rings. Curious on what you guys think.

 
You should have asked them specifically if the photo of the piston kit is EXACTLY what you would receive if you bought them.

You do realize your asking a Chinese guy, who may not fully understand your inquiry (I have nothing against Chinese people) I worked directly with and for Chinese people for 6 years, so I know what I am talking about... You may have to ask the same question a few different way till it sinks in. You have to remember they are always thinking in Chinese and not in English.

I know that may sound bad but in no way it is meant racial in any way.
 
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
Last edit: 18 Jan 2026 17:55 by Injected. Reason: more info

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Re: Terrible motor swap idea kz440

18 Jan 2026 18:41
#920757
I understand what you are saying. It's possible that some of the specifics could be lost in the translation. I sent them a response with pictures showing that these pistons look very similar to mine and whatnot. I hope they understand what point I'm trying to get across.
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

18 Jan 2026 19:52 - 18 Jan 2026 19:55
#920760
That Company may be selling kits for dozens of different sizes and makes of engines so in some cases they are NOT experts in all makes or know what fits what. It could also be some sort of typo mistake, I have seen plenty of that on Ebay with sellers unknowingly identifying items happily to my benefit :)

If worse comes to worse you could order it, its not like its a $800 kit that could not be recouped in some way. Plus if they say its for a certain year and its not, would you not be covered under Ebay's buyer protection plan? for misrepresenting a item fitment??
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
Last edit: 18 Jan 2026 19:55 by Injected. Reason: sp
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Re: Terrible motor swap idea kz440

18 Jan 2026 20:45
#920763
I think that I'll just send it on the piston kit and if they dont clear the head, I'll get a different head if worse comes to worst. Only problem from my understanding is getting the carbs to fit.
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

19 Jan 2026 13:20
#920775
My heart, my soul,
Oh, where shall I go?
Without you, I am cold...

Making you right is my goal,
But back to college I shall go,
For staying too long is bold.

When I fix you my mind flows
With dream of riding you on the road
Until my body crumbles to coal.
 
Aww man, this bike got me feeling poetic 
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig
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Re: Terrible motor swap idea kz440

21 Jan 2026 09:32
#920825
Im interested in finding a windshield but they seem to be nonexistent so I was wondering if it's possible to fabricate one? Do you guys know about someone who has done this or any material to use? Thanks!
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

21 Jan 2026 10:04
#920828
Im interested in finding a windshield but they seem to be nonexistent so I was wondering if it's possible to fabricate one? Do you guys know about someone who has done this or any material to use? Thanks!
seem to be readily available in Europe, you better order quick before the additional tariffs come into force 

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Re: Terrible motor swap idea kz440

21 Jan 2026 11:55
#920837
Holy smokes! I dont think I'm ready to spend close to $200 usd on a piece of clear plastic! I would rather use a piece of pliable plastic and cut it to shape. If you know anything about doing that, I would love to hear about it!
1982 KZ1000M2 CSR
1983 KZ440D5 LTD
1985 GPz 550A2?

Craig

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Re: Terrible motor swap idea kz440

21 Jan 2026 12:15
#920839
It’s not cheap but it is a low volume production part. The original is curved in two directions which you won’t be able to replicate. I have done some plastic forming on my current project. You could make a cardboard template then cut it in plastic, bend it cold to bolt into place then heat with a hot air gun to relieve the stress. However you will get one shot at this and if you overheat it you don’t have the luxury of sanding and painting afterwards with clear. Also research the plastic you intend to use- you don’t want anything that will shatter in a frontal impact then “cut your throat” when you are thrown forward!!!
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