Z1 as a project?

[MrDavo]

I'm going to bite the bullet and buy Kawasaki genuine head gaskets, the ones in my generic gasket set are no better than the ones I've taken out.

The real thing costs an arm and a leg (£151 pre discount and P&P) for the pair, however when I did my CB750 I paid over £110 for a real head gasket, because they work every time.

I'll never know for sure, but maybe I could have got away with just retorquing the head rather than pull it all to bits. I would still have been on knockoff gaskets and valve seals though, if I use the best I know I've done the best job I can. The Viton valve seals showed up this morning.

[royhall]

I was advised to use a Cometic head gasket on the GS1000, made in the good old USofA. I was impressed with the quality of the gasket, and it was a perfect fit. The one in the gasket set didn't even fit the dowel spacings correctly so it went into the bin. I had some very similar problems with the Suzuki with the Hi-Level head gasket that was fitted being soaked through with oil, that lasted 800 miles and the head bolts were loose just like yours. I think some of the gaskets in the sets are complete rubbish.

Maybe something like this   [size=78%]Cometic Motorcycle C8019 Head Gasket Kawasaki Z1 900 73-75 KZ900A 76 -77 KZ1000J | eBay[/size]
May not suitable for yours but these are quality gaskets, it does list this as fits 1973 Z1.

[MrDavo]

I have already taken out a second mortgage to fund the genuine KHI head gaskets, Roy. You can fit the one piece Cometic gaskets, but the groove for the wiggly rubber gasket around the camchain tunnel has to be filled with sealant first. The name Cometic keeps coming up though as an alternative to OEM that won't break the bank.

Interesting what you said about your Suzuki head bolts loosening as your gasket failed, I'm sure I did check the torque, at the same time as I took the cam cover off to lube the dry cams.

[royhall]

Dave. If it was me, I would take the pistons off the conrods (after numbering them to the bores) and take them with the barrels to someone that does re-bores and get them to measure the clearance accurately. There's no way you can measure them accurately enough with calipers. If they are even slightly oversize these 900/1000 engines will smoke like bonfire night. The guides need to be good as well, if they are loose the valve movement will destroy you new Viton seals.

[K2-K6]

I agree with Roy in checking as much as possible,  it'd be even more of a pain to reassemble only to find it unresolved.

The gaskets certainly look compromised,  but don't appear to tally with that much oil going through the cylinders, well not without some also being visible externally too.

I'd suspect the other elements until proven as measured within correct tolerances.

[MrDavo]

OK, while I want to get back on the road ASAP, and get my car in the garage again, I really want to ‘do it properly and do it once’. I really don’t want to be pulling it apart again in a few weeks, as said earlier this is how barn finds are born. My CL450 had been put together with a loose camchain idler spindle (the locating knockpin was in the sump) and witness marks showed it had been bouncing off the barrel skirts, it must have sounded awful. Someone had already spent time and money only to hear this racket, I reckon that’s when it went under a dust sheet for a few decades.

I’m away next week, but when I get back I’ll take the barrels and pistons to an engineering firm that has been recommended by a mate in the classic bike trade, for a spot of measuring. With the cost of real head gaskets I’m not installing one for a few oily miles again.

[MrDavo]

I just got back from Stockport, where I have dropped the barrels and pistons off at Quasar Engineering, which come recommended by my mate in the classic bike trade.

I included a sheet saying what (and why) I need measuring, plus a copy of the page from the workshop manual dealing with piston clearances. If the measurements show that the rebore was cocked up, then +1.0mm pistons are avaiable, though I don't want to use up the rebores if I don't have to.

While I wait I need to sort the head out, here I have fitted the Viton valve seals, using the wheelie bin again as an outdoor workbench.



For the sake of my sanity and valve clearances I had been warned that under no circumstances should I get shims and valves etc mixed up. A root around revealed a tray (with lid) for dips, nuts etc that we inherited from my Mother in Law. Once at the centre of the dinner table, with its 8 compartments it turned out to be just what I needed!

[Laverda Dave]

Are your shims on the top of the buckets Dave? Much easier to have them on the top rather than under the bucket as they are on the Z400J.

[kevski]

Over bucket shims on the 900/1000's at least up to 1981, they have been known to spit them out on the odd occasion though resulting in an expensive rebuild.

[Bryanj]

Only seen them spit out in extreme high rev situations

[MrDavo]

After a promising start, the Z1A is now being used as a paper towel dispenser.



As mentioned in my last post, the barrels and pistons are away at an engineering firm being properly measured for clearance. As well as reassembling the head with new valve seals, I also need another look in the carbs, I will have to resynch them after. I have a new NOS adjuster to replace the one I broke, also I assumed that all the needles were in the right place. The clips should be on the third groove down, however this photo I took when I was sorting out a battered pilot jet holder clearly shows the needle in position 4, this is how I found it and probably how it went back together, so I need to check all four. Maybe it will help the slow speed running, at the moment the air screws seem to make beggar all difference.

[AshimotoK0]

I just made a .pdf from this old 80's article Dave. I guess you have it already but may be of interest to others. Just about readable 

Click on Link for full article    :--


https://www.dropbox.com/s/pacj8e2usra1r56/Z.pdf?dl=0



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[AshimotoK0]

Dave Marsden looked so young in that article    and interesting that the translation from Japanese to English on the 'idiot light' panel was wrong. Bet those cocked-up panels are worth a bit. Does anyone know if he still has that bike?

[Laverda Dave]

I remember that article Ash and the one at roughly the same time when Bob Berry tested a South African version (in metallic green) that was limited to 750cc.
I also remember Bob's CBX rebuild, what happened to that bike? I think Bob Berry went on to edit 'The Biker'.

[MrDavo]

Somewhere I'm sure I've read a blog by Dave Marsden on building a Z1 from new parts he had stashed away, but I can't find it on the Z Power site. Fancy turning down £4,500 for it!!

Good news from the engineering shop today, he's finally had the chance to measure everything up, and the piston to bore clearances are fine and within spec at 3 thou. That's a big relief, I didn't want to use up my second rebore if I didn't have to, never mind the cost of another set of pistons.

There were two things to point out, one was that, as predicted, running in gently with modern synthetic was a mistake, the bores looked lightly glazed rather than run in. he's going to give the bores a very light hone, and I'll chuck some straight mineral oil in for the first 500 miles this time, and not 'baby' it too much.

The other observation was that the piston expander rings (under the oil rings) didn't seem to be doing a lot. I don't know if they can take a set over time if installed and then not used for years, but using 'an abundance of caution' (as they keep saying over Covid rules these days) I've ordered a new set of +0.5mm rings, as well as new circlips, from Z Power.