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Cylinder wall condition. 06 Dec 2017 07:05 #775633

  • gordone
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Hi,

I have open up my engine, and consider the cylinders to be honed or not...
I have not find deep scratch, but I have not a trained eye for it...

When I first have the engine open, will I do everything properly.

I have uploaded photo:
temp.dynamitt.net/div/MC/cylinder/

If I can take photos another way please let me know.

Thank you all for input and support during my rebuild of the bike.
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Last edit: by gordone.

Cylinder wall condition. 06 Dec 2017 07:31 #775636

  • SWest
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I would combine the two threads. It looks like moisture got into the cylinders judging by the staining. You could try a hone but chances are those bores will have to be bored. Try uploading pics using the attachment and add file buttons. The different color on the valves suggest the amount of oil getting past the rings.
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229
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Cylinder wall condition. 06 Dec 2017 07:40 #775641

  • Nessism
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Photos can be posted easily by bracketing the direct image link (must end in .jpg or similar) as shown below.

For example: {img]https://photo link.jpg[/img} (must replace { with [ in the example),

Those cylinders look corrosion pitted where the rings parked on the cylinder wall. Most likely will need a bore job.

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Last edit: by Nessism.

Cylinder wall condition. 06 Dec 2017 07:45 #775642

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I have taken picture with high resolution, so hard to upload there where you have 5mb max...

Cylinders:
temp.dynamitt.net/div/MC/cylinder/

Valve:
temp.dynamitt.net/div/MC/valve/

Piston:
temp.dynamitt.net/div/MC/piston/

Do you have problem to open I can upload to another site, you shall be able to zoom into the picture, since they have high resolution.

So based on the co lour it looks like oil leaking through valve, the oil seal on the valve it self is leaking then?
My plan was to clean everything and replace the valve sealing...

So you suggest to boring the cylinders? Can it just be bad piston rings?
I can add that the engine has runs fine before I open up the engine it was only leaking from the head gasket...

Cylinders:
1. Honing cylinders?
2. Borring cylinders?

Top:
1. Replace the oil sealing on the valves?
2. Deliver the top in for overhaul valves? both seat and the valve it self? or is the best to purchase new valves and let a workshop machining the valve seats?
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Cylinder wall condition. 06 Dec 2017 07:47 #775643

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Nessism wrote: Photos can be posted easily by bracketing the direct image link (must end in .jpg or similar) as shown below.

For example: {img]https://photo link.jpg[/img} (must replace { with [ in the example),

Those cylinders look corrosion pitted where the rings parked on the cylinder wall. Most likely will need a bore job.


Can I take some more photos from another angle or something, so you are 100% sure I need for bore them?
Will I be able to reuse the same piston after the bore job?

What about the top and the valves? should I do something there also?
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Cylinder wall condition. 06 Dec 2017 08:19 #775644

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Looks like bad valve guide seals. A hone may do it but the stains go deep into the porous sleeves. If not pitted, they can be reused maybe. Better to get a good used set of barrels and change the rings. Check the condition of the valves guides and seats. May be able to lap them maybe again.
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229
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Cylinder wall condition. 06 Dec 2017 08:56 #775645

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SWest wrote: Looks like bad valve guide seals. A hone may do it but the stains go deep into the porous sleeves. If not pitted, they can be reused maybe. Better to get a good used set of barrels and change the rings. Check the condition of the valves guides and seats. May be able to lap them maybe again.
Steve


I need to ask to be sure I understand you correct :)
1.
There are a big risk boring will not help, because it can be to deep?
There is no way I can check these, it will be clarified when I the boring has been done only?
And the problem is, you cannot remove to much of the steel?

2.
So the best and cheapest I can do is to get a new used barrels and maybe delivered to a workshop for honing to get it 100%
condition?

3.
Are there a chance for the pictures is lying?
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Cylinder wall condition. 06 Dec 2017 09:02 #775647

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A good used set of barrels is the cheapest way that is unless you want to big bore for more power, then it gets $$$.
Steve
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229

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Cylinder wall condition. 06 Dec 2017 09:41 #775649

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SWest wrote: A good used set of barrels is the cheapest way that is unless you want to big bore for more power, then it gets $$$.
Steve


Thank you for your quick feedback, as I understand have I 3 options.

1.
Get a new barrets, in good condition. When I receive it must I consider honing or not? A honing job will make better performance
and it will worker for longer before I got any problems?

2.
borr less as possible and honing to get the cylinders in good condition.
Can it be I need to get new piston also then?

3.
Borring to get higher performance, how much mm are we talking about ? what is mm dimension original and what is normal to go up to? I have carbs from a 650mm engine today, so maybe I will get problem and re jetting will not help?
Is there other problems I got / upgrades need to be done?
Job include, borring, new pistons and rings + new jets for the carbs?
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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Last edit: by gordone.

Cylinder wall condition. 06 Dec 2017 09:42 #775650

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I would try and scuff first with a 1500 grit wet paper . See if it sarts to deminich the blemishes. If it does, hone and new rings. Make certain pistons are in spec.
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Cylinder wall condition. 06 Dec 2017 09:55 #775651

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I would get them honed first, if they are still bad have them re-bored with new pistons, any used sets of cylinders out there will need to be honed and possibly re-bored therefore adding more money to the build.

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Cylinder wall condition. 06 Dec 2017 10:56 #775655

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kevski wrote: I would get them honed first, if they are still bad have them re-bored with new pistons, any used sets of cylinders out there will need to be honed and possibly re-bored therefore adding more money to the build.


re-bored with new pistons, what size do I need to go up to?
I must properly inform the workshop what piston I shall use and what they shall borr to?

I will check with wet sanding tomorrow to see if the mark disappear or not.
1981 KZ650-D4, with 1981 z750L engine (Wiensco 810 big bore).

Project:
www.kzrider.com/forum/11-projects/607213...sr-1981-z750l-engine

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