Oily pipes, fresh Z1A

[MrDavo]

Good news from the engineering shop today, he's finally had the chance to measure everything up, and the piston to bore clearance is 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.

[MrDavo]

The motor is mostly back together now, with new rings and valve seals, plus a light hone. Hoere's a photo I took yesterday of the cams being timed. I've never done this before on a Kawasaki, but following instructions on the forum it was straightforward enough. Note the paint dots on the cam sprockets and chain, at zero and 28 links.



Despite keeping all the parts for each cylinder separate, and not regrinding all the valve seats (i'd only done 375 miles), a couple of my valve clearances are right up the pictures, much to my disappointment. Two are under, (practically zero) two are on the big side at .15mm, so I'll try swapping the shims around.

I dont know how that happened, if you put all the same parts back where they came from everything should be exactly the same. But they aren't, and we are where we are. Luckily there is an excellent guide to valve clearance setting on the forum, I've ordered a genuine shim tool and, following advice on that thread, one of the smallest thickness shims, so I have a spare when swapping around the shims, and a way of remeasuring the two with virtually no clearance.

[MrDavo]

jumping back a stage, but I had to dig out this photo last night, as I was worried that I hadn't considered which way up the head gasket should be. as it happens you can see I did do it right. You can also see the hatching from the light hone the engineering shop applied to my glazed bores. I'm now using Tescos mineral oil for running in, last night as I poured it in the smell brought back memories, mainly of being covered in the stuff.....



I got a 2.0 shim from Z Power., so I could measure the clearance on the two valves with zero clearance, and to give me an extra to do some swapping around between the tight ones and the wide. I also got the genuine tool to make life easier. I had to buy a single 230 shim to get one in spec, they are finally all within the .05 to .15 (as modified from 0.10 in a service bulletin which I've read about but not actually seen) range now, so happy days, exhaust pipes and cam cover are back on. I'm at the Silverstone Classic this weekend, but next week I only have to assemble and readjust the carbs and I can have another go at running her in.

[ADRIAN H]

Original manual - tappet clearance 0.05 - 0.10mm.

Service bulletin 74 Z-4 (22.11.74) - Measured tappet clearance updated to between 0.11 - 0.14 mm

[MrDavo]

Thanks for that Adrian, so the change was when my bike was only a few months old, not years later.

I haven't got them in front of me, but one of my manuals (I have the real thing and a Haynes one) was trying to kill my cam shaft keeper bolt threads with a misprint - I was thinking 'this feels stupidly tight' and went to double check the torque setting, some people have stripped them all. I think it was saying 12 ft pounds when it should have been nearer 6 (actually given in inch lbs). If I ever have to do it again I may strap the cams down with zip ties or something, you are at a stage when you can't turn the motor yet but are fighting the valve springs to tighten the caps down.