TOPIC:

...and some more pics of my tools i use for the valve guide job






And some reamers for the ID of the valve guide in 6,98/6,99/7,00 mm size.

You're saying you don't align the seats?
Steve

Yes, Steve of course, i would do/can do the job by my self.
It is a must to do, to verify a correct valve guide install and valve to valve seat position and angle.
But not all of us have the right tools or serdi mashine to do the valve job after the valve guide job.
I shall limit myself to the new valve guide installing topic.
Trust me i learned my lessons by my own errors and this is a very difficult job for a rookie.
Luckily i have a full access to the machine park and tools of my steel manufacturing company if i need it.

Agreed.
Steve

Good evening Guys,
I have read your topic with interest.
I have recently stripped a Z900 A4 US import engine and had it vapour blasted, whilst its come up like new which is great, now I've come to rebuild its highlighted a couple of issues on the head now all carbons removed.
Firstly looking into the plug holes from combustion side you can see what looks like stress fractures in the plug hole threads not bad but there, 1 has been helicoiled. Whats your thoughts on this and can it be rectified, or ignored?
Secondly none of the valves appear worn and the inlets have very little guide wear, the exhausts guides alas do. Whats most cost effective solution as moneys tight.
Ive reaIvebout guide knurling any good, longevity?
if i go down the replacement guide route, how much can be done myself, or should i just send it away. To a machine shop?
this would be my preference if money wasnt an issue, but would like to keep expenditure to a minimum.
note before stripping bike ran fine with no smoke, but obv had a lot of carbon, now it doesnt hence question.
Many thanks for any advice

What was the compression like prior to disassembly?  Those cracks look like they are deep, and might affect compression.  It's not unusual to see cracks like that but those look pretty big.

Thanks for reply, to be honest they were all within a few psi of each other, noted them down but cant find paper. It also ran ok and ticked over ok, but as its not yet uk registered never got chance to ride it on the road though, literally bought it, was supposed to have been part restored with new parts fitted, just needing finishing but found lots of the jobs not done very well, hence full strip down. Engine had been sprayed silver so it looked good, Frame brush painted, also painted none standard etc. I've ended up doing a full resto.
frame and all chassis parts powder coated, new tank panel paint back to original with new decals, engine strip vapour blasted, found a couple of cam chain rollers collapsed so lucky i stripped it, now this.
its cost a fortune so far and could have well done without this on top.
any advice appreciated on best way to tackle the head. Did think plugs sealed on top of head with flat washer, so hoping the cracks wouldnt hurt?
Thanks

I would agree with HRM that those cracks whilst not uncommon do look significant. Regards the guides, if money is tight then I wouldn't recommend cutting your teeth on this as your first attempt (you will also need to spend on tooling) worn guides won't cause it to smoke as the stem seals should stop oil entering (however worn guides will prematurely wear the seals, I guess it depends on how much you intend to use the bike)
I would be more concerned about the cracks as worst case is that the valve seats could start to drift out if enough tension is lost through the crack. This would stop the valves closing fully which could cause some mechanical love making. The cracks can be repaired by "stitch welding" etc but I have no idea of the cost. I have included a link to a company in Coventry that do this sort of work, might be worth giving them a call

www.metalockengineering.com/en/metalock-...uk-limited/services/

Here is another one in Measham that will quote from a photo of the damage (crack)
www.castironweldingrepairs.co.uk/metal-stitching-process.php

 

Thanks for the info i have sent them an email with photo for a quote to repair.
its got me even more worried now as def didnt expect that, wishing i hadnt had the vapour blasting done as the carbon build up was masking it to a degree, but it would have had to be done at some point!
As for use, im getting on a bit now so very limited use probably only 1000 miles a year mostly trips up to the coast and back on a weekend,(if i ever get it back together as keep finding more probs) as you say the new seals will take up some of the wear but wear out quickly, that said considering the ammount of play im surprised the seats or valves havn't more damage showing they look perfect?
had a quote for valve guide replacement and seat recut £105 but i buy the 4 exhaust guides, timescales an issue as very busy argh!

So the bike will be a Sunday ride thing...not a daily rider.

If compression on those cylinders with cracks was good then you might want to consider putting everything back together without fixing the cracks or replacing the exhaust guides.  Just replace the valve seals.  You will also require a set of head gaskets.  Those will be your most expensive purchase.  Go with OEM if possible.
 

Thank you, yes already have the full gasket set not oem though but look decent quality.
I am awaiting quotes from the 2 firms Wookie sent me, see what sort of price comes back.
have ordered new guides already from Zpower genuine Kawasaki ones. I will take the advice and not have a go myself, with my luck at mo id prob do more damage then good, besides as pointed out, by the time ive bought the insert tool and 7mm reamer your nearly at cost of a proffessional doing it properly and prob only need them the once!
living where i do makes it awkward as very few places nearby, which is a pain.