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Z650 cylinder head

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Mark W
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Z650 cylinder head

#1 PostAuthor: Mark W » Fri Sep 06, 2024 4:18 pm

Taking apart my z650 1979 cylinder head has proved difficult and have found that the carb intake flange was stuck on with window sealer,one of the bolts has sheared off.The exhaust studs have damage and has split the housing,so needs welding.Should I just ditch the head and go on to the dreaded e bay or get it repaired?Also are the camshafts bored and matched to the head meaning I would have get a complete top end ?
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moizeau
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Re: Z650 cylinder head

#2 PostAuthor: moizeau » Fri Sep 06, 2024 4:32 pm

Make sure the cam caps are included, they are the important bit as far as I'm aware. I have a spare engine from a D model, the head 'seems' good but untested.
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Gray17
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Re: Z650 cylinder head

#3 PostAuthor: Gray17 » Fri Sep 06, 2024 5:14 pm

Im no expert, but that looks pretty bad to me, by the look of the aluminium in parts it looks like theres a few areas that need attention, welding and re drilling and tapping etc, in my humble opinion if it was mine and assuming you cant do all the work yourself, the cost wouldnt be worth it in the long run.
Personally i'd get a replacement head, perhaps try forum members 1st before ebay, more likely to get a better replacement.
Hope you get sorted.

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warren3200gt
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Re: Z650 cylinder head

#4 PostAuthor: warren3200gt » Fri Sep 06, 2024 6:22 pm

The cam caps and seats are line bored as one piece to ensure alignment on 650's. Also the cams guides don't have shells so it's vitally important any head you get comes with the original cam caps.
Your existing heads is not going to be cost effective to repair unless you can do it yourself and as 650 heads are not difficult to come by that would be your best route.
Check stem guides for wear, reseat the valves and use new valve seals.
I would be checking Peters offer out first before hitting ebay lottery.
PUM 488 June 2026
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

Mark W
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Location: Kent

Re: Z650 cylinder head

#5 PostAuthor: Mark W » Fri Sep 06, 2024 7:44 pm

Thanks for the help guys,I am taking the head to an engineering place in east grinstead for them to have a look on Monday,if I need to take you up on your offer I will let you know.I have managed to remove the broken inlet stud and all but 2 of the exhaust studs,it would be handy to keep the existing head as a known quantity.On taking the head apart I noticed that the manual cam chain tensioner had the lock bolt facing the right hand side of the engine,my z900 has got it facing the left,does it matter?

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warren3200gt
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Re: Z650 cylinder head

#6 PostAuthor: warren3200gt » Fri Sep 06, 2024 8:14 pm

No, the tensioner can be mounted either way. From the factory the lock bolt/nut was on the left as you sit on the bike.
PUM 488 June 2026
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

Mark W
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Location: Kent

Re: Z650 cylinder head

#7 PostAuthor: Mark W » Wed Sep 11, 2024 11:58 am

Hi guys my cylinder head has been fixed by a friendly engineering place a mile down the road for £50
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Gray17
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Re: Z650 cylinder head

#8 PostAuthor: Gray17 » Wed Sep 11, 2024 4:39 pm

Wow, thats 100% better then it was, hopefully it hasnt weakened the alloy on the other areas. Hopefully not, £50 a bargain really considering how it looked i thought it was scrap.
Personally id get it vapour blasted and head skimmed whilst removed and check valve guides too.

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ADRIAN H
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Re: Z650 cylinder head

#9 PostAuthor: ADRIAN H » Wed Sep 11, 2024 5:09 pm

That looks spot on, pleased for you.
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