Z900 A4 Cylinder head refurb (advice needed please)

[Gray17]

Thanks for info, im coming round to that way of thinking myself, could have done without it, what with all other resto costs spiralling ever upwards but heyho! It is whar it is. Ive ordered a guide set from Zpower genuine kawasaki, I've also just sent an email over to Roger asking for quote to fit guides and recut seats.
So once they arrive i can make a final decision and hopefully get the head ready to be re fitted.
Thanks all

[sean_rfi]

You could also consider having K-Line valve guide inserts fitted. This saves having to press out the original guides.
There are a few companies that offer this option.

https://www.klineind.com/k-line-service ... ystem.html

http://www.jandeengineering.co.uk/valveguides.html

[Gray17]

Thanks for the info Sean, they look like an excellent alternative.
i have sent an email asking for a quote, but have already odered new exhaust valve guides from Zpower genuine Kawasaki ones.
Just need someone decent locally to fit them and re cut seats, then theres the clearences and shims argh! List just goes on and on!

[zed1015]

Which guides have you ordered and what valves are you using.
You should be aware that you cannot use the later round keeper groove valves in the earlier OEM bronze guides as their materials are incompatible and will quickly cause galling, excessive wear etc.
You can however run both early square and late round keeper valves in the later cast iron guides..
The OEM bronze guides should be avoided anyway as they were of an inferior material and prone to excessive which is why Kawasaki switched to cast iron.
I don't see the early bronze guides listed on Zpower anyway so you are probably ok.

[Gray17]

Its the pack of 4 exhaust guides ive ordered, (part no.49002-1002G ) did call Zpower to check part numbers are diff to the ones in the parts list, thay informed that the original ones have been suoerseeded by the new ones.
So hope these are ok. As for the valves using the originals as there apoears little or no wear on the stems or seats. If cost wasnt an issue i'd replace everything inlet and exhaust guides, valves and springs but it is so have to econonmise somewhere.
I have also heard back from Roger in Leeds regarding the guide fitment, basically he's so busy he cant undertake any more work until after June, so yet another choice wait for him or find another installer, it was the same at my local firm they too have long lead time but not as bad as June. As for the stress cracks, as mentioned he states most live with them due to being uneconomical to repair, however assume they can be repaired but cost may be prohibitive?.
Ive also read Kawasaki themselves have re cast brand new cylinder heads, but of course very expensive, even looked at used but there rare and the ones available probably worst or at least as bad as mine anyway. Ive even considered fitting the guides myself but even if i bought the correct tools and 7mm reamer theres still the valve seat re cut, the chances the new guides going in in exactly the same place and angle is slim to say the least.
Thanks all for info though, its appreciated

FYI
Further to yesterdays emails, i have today received a reply from the company in uk doing the k line inserts (Jonathon Atkin), they have advised that whilst they are suitable for motorcycles J and E wont fit them to motorcycles at all, not sure why, which is a shame.
The other companies i emailed regarding the alloy welds of stress cracks, have not even bothered to reply, so guess they dont want the work either!

[Ultim8pc]

Then stress cracks are a non issue and I wouldn't worry about them. They are common. If you weld the they may well come back.
I've had guides K-lines before and it's not much cheaper than new guides. Sadly two of the companies I used to use for both have retired.
You could try Buzzard at Buzzworks or Brian at Centurion Motorcycles. Both carry out high quality work, but like most good places they can't generally do work without a wait time.
if the valve stems measure to be within tolerance according to the workshop manual then they are ok to reuse.
If you are fitting new guides or re-lining them you really should get your seats re-cut in my onion as there is no guarantee that the centre of the guide will match the seat.
I can do most things but I get guides and seats done by people who do it for a living. They'll get it right and if it's not you have comeback.

[Gray17]

Thanks for that, well the guides arrived from Zpower, again excellent service, as you mentioned they are now no longer bronxe, like a silver alloy. Anyway i used my digital callipers on all 8 valves at 3 diff locations, very little wear present. I then tried the 4 exhaust valves in the new guides, fit was perfect, but decided not to jump in and have a go to save money, i've entrusted it to a local eng workshop, who has fitted it in for me as initially they told me a month at least. They are an old faschioned type place with proper engineers who know there stuff, lots of businesses entrust them to do their engineering work and ive had work done by them before, always excellent and never rip you off, prob why their always so busy. Any way i took it in and straight away without prompt they recognised it as a Z1/900, i told them the story and they had a look. As well as the valve guides and recut seats they are also doing the valves too and trimming the ends to the same tolerence they take off the seats, they tell me i should be able to use the same shim size assuming it was ok to start with.
They also recommended a head skim, pressure test and noticed a previously helicoil in plug had been done badly and was sat proud, not only that but they also noticed the stress fracture in the other plug thread and are sorting both of them out too.
They say it will be ready in about a week, which im over the moon about as most were talking months!
Of course it wasnt cheap, but then what price is top quality work and peace of mind, plus once rebuilt it will see my biking days out thats for sure.
Many thanks to all for the help and advice without which i would have really struggled to make an informed decision, yes the internets great but it only goes so far, experience cant be beaten.

[Ultim8pc]

Thanks for that, well the guides arrived from Zpower, again excellent service, as you mentioned they are now no longer bronxe, like a silver alloy. Anyway i used my digital callipers on all 8 valves at 3 diff locations, very little wear present. I then tried the 4 exhaust valves in the new guides, fit was perfect, but decided not to jump in and have a ho to save money, i've entrusted it to a local eng workshop, who has fitted it in for me as initially they told me a month at least. They are an old faschioned type place with proper engineers who know there stuff, lots of businesses entrust them to do their engineering work and ive had work done by them before, always excellent and never rip you off, prob why their always so busy. Any way i took it in and straight away without prompt they recognised it as a Z1/900, i told them the story and they had a look. As well as the valve guides and recut seats they are also doing the valves too and trimming the ends to the same tolerence they take off the seats, they tell me i should be able to use the same shim size assuming it was ok to start with.
They also recommended a head skim, pressure test and noticed a previously helicoil in plug had been done badly and was sat proud, not only that but they also noticed the stress fracture in the other ug thread and are sorting both of them out too.
They say it will be ready in about a week, which im over the moon about as most were tslking months!
Of course it wasnt cheap, but then what price in top quality work and peace of mind, plus once rebuilt it will see my biking days out thats for sure.
Many thanks to all for the help and advice without which i would have really struggled to make an informed decision, yes the internets great but it only goes so far, experience cant be beaten.

Glad you are getting sorted. Please keep us posted.

[Gray17]

Will do, i will upload a photo once i get head back

[Gray17]

Hi Guys, well just got cylinder head back from engineering company.
Work carried out: fit supplied valve guides (from Zpower) re cut valve seats, lap valves in, skim head, pressure test, remove badly fitting helicoil (standing proud) and fit 2 new timeserts, 1 for the duff helicoil and the other to remove micro fracture on plug thread seen in original photo. Alas 1 exhaust stud snapped when being removed they have drilled it and re tapped to 6mm so i now need a new stud, apoarently they had to remove them to allow skimming. Anyway its back.
Also in foreground on photo the 3 cam roller bearings have arrived, i asked for INA as per Zeds recomendation but got IKO, which according to Google are better but ?
Lots of work now to keep me busy, got everything i need to complete engine rebuild. Just got the dreaded shim clearences to sort out.
On a plus note they have ground ba k the valves heads to be the same tollerance as before the work started, so with luck may not need any new shims, time will tell on that one.
On another note they asked if engine ran, which it did, they said it would have not lasted long as the plug helicoil had been glued in and probably would have leaked, when i look closely whoever did it ran a double washer on plug to take up distance, dreadful, what a bodge!
Any way will keep you all posted on my progress.
Just need a decent fuel

tank now!!!!