KAWASAKI Z1300
Ralph gets the mighty Z1300’s top off and finds issues that he needs to sort out.
Ralph is sorting the valves on his mighty six this month.
In my last scribblings about my icon of 70s motorcycle excess, I dismantled what has to be the most interesting sump I have come across and measured all six bores of the engine. Realising that the barrels were glazed and had to be removed to be lightly honed, I decided that given how much of the engine was now spread out around my workshop I may just as well pull the remaining lump from the bike and repaint it, as the previous paint was now looking a tad less than pristine and while I am no collector of show ponies, I don’t like my bikes to look rough. In an ideal world where I had inexhaustible resources and time, I would have stripped the whole powerplant down to its last nut and bolt and bead blasted each and every surface to be coated before applying a top industrial paint covering, but sadly time and boundless wealth are resources that are both in very short supply in my world. I did however mask up the sump and give that a good old blast.
Good quality gaffer tape is good for masking up for glass bead blasting. The blasted finish makes a perfect key for paint. Once I had used compressed air to throw ground up glass at it, I removed the gaffer tape masking and used some IPA (Isopropyl Alcohol) to remove the glue residue. I then re-masked it all with masking tape, but only the bottom as I would be sitting it upside down on a piece of flat wood to spray it. I managed to get some genuine VHT engine paint, made in the US, via ebay. I took the sump out to the garden to paint because the fumes are not good for one’s health. With the ambient temperature being so low at the time, once the paint had cured for a while I popped it in the wife’s oven to harden off: while she was out, clearly! There is no real need to bake paint, but in the winter it will speed up the full hardening process. The next job was to take a look at the head. The first thing to be tackled was the shims. I knew from the last time I had re-shimmed the head during its most recent service that all the shims were on the thin side. Some actually on the thinnest size – 2.00mm. At this point I must say that if you have a head with thin shims that go under the minimum size the answer is NOT to get the shim ground thinner! Shims are usually case hardened and if they are ground, the hardening will be removed leaving their softer centre to the ravages of the pounding cam lobes. Judging by the surface finish on a number of the shims in the Z1300’s head, she may have been abused in this manner previously. The first job was to completely strip the head and ascertain what was right and what wasn’t, so I fitted a set of head stands, which make life so much easier. Given how reasonable in the price department they are, it amazes why folk struggle without. I see a lot of Diyers using the lever type valve spring compressors, probably because they are cheaper, but a proper motorcycle valve spring compressor set is much more flexible and an easier tool to use. I used a labelled, multi compartment storage box made by Stanley from one of the large DIY sheds to store and keep separate all the valve components. Once the spring is compressed, depending on my mood I’ll either remove the collets with a pair of curved nose forceps or as in this case a magnetic pickup tool. I used a pick tool to tease the valve springs and the spring retainer. I used my fancy stem seal removal pliers to pull the stem seals off the guides. I only use it because I spent money on it, but have used the hook tool from a pick set to good effect in the past. A pick set is an absolute must and will perform a million tasks, whereas stem seal pliers are very much a one trick pony and were they to break, they probably
wouldn’t get replaced. The seals that came off may well have been responsible for much if not all the smoking the engine did. They were the cheap sort that came with pattern gasket sets. They are not worth using. I always use Viton seals that I get from Joe Hooper in the States via ebay. They’re expensive for stem seals, but cheap compared with the expense of a top-end rebuild. I again used the small magnetic pickup tool to extricate the spring seat. All engines will have a build-up of the deposits of combustion on the valves, pistons and head. Once the valves are removed I clean them up on a wire wheel on the bench grinder/polishing spindle. With any process that generates a lot of dust, you should wear a face mask to reduce the inhalation of airborne particles, but if you suspect that the engine hasn’t been de-coked since running on leaded fuel you need to be extra careful. Somewhat counterintuitively lead on valves etc. is a white(ish) deposit and is very damaging to breathe. To clean the deposits from the combustion chambers and ports I tend to use a fine wire wheel in my Dremel. I have tried the brass wheels, but have found that they tend to leave a brass residue and don’t really clean as well. The steel haired brushes employed gently do a great job and providing a degree of care and subtlety is employed, I have found that they don’t mark the castings. The only downside is that they do tend to moult and they can stab your skin! Once the head was properly clean I removed the pistons. I used a pukka gudgeon pin removal tool. Always buy new piston pin circlips as they only cost buttons and the result of a tired circlip letting go is unthinkable. They are a ‘use once and discard’ item. I have witnessed people drifting the pins out with all sorts of implements including screw drivers, pin punches, nails, bolts etc, but this is a bad thing because it puts undue pressure in the connecting rods and big-ends. With the pistons sitting like a row of stumpy soldiers on the bench I carefully gripped one at a time in the soft-jaws of my bench vice for a clean-up and to divest them of their rings using my piston ring expander pliers. Again I employed the Dremel multi tool with the baby wire wheel to disencumber the piston crowns of the carbon build up. I bought a new full set of rings from Kawasaki, which was a long way from cheap, but thankfully they were available. I usually give the piston crowns a quick polish on the medium grade buffing wheel because the smoother the surface the less inclined carbon etc. is to adhere to it. Once the valves and head were clean, I examined and measured all the components. The valves springs were measured to ensure that they were within
tolerance. The workshop manual gives the minimum length of each spring and I checked them with my digital calipers and all were correct. I then measured all the valve stems with a micrometer screw gauge and found they were also well within tolerance. The exhaust valve guides however were not and so had to be replaced. The guides are the same as used by other big Zeds of this age and are still available. It is possible to heat up a cylinder head in an oven and then drift out the old guides with a special tool and refit the new ones in the same manner. Unfortunately, I don’t have an oven big enough for a standard Z1 head, much less the prodigious lump that is the big six head, so I had to take it to an auto engineering company. Sadly, the old boy who used to do all my auto engineering work became unwell and had to give up on his business, so with a heavy heart I had to look for an alternative. I came upon a local business with a very tidy workshop, more akin to an operating theatre, who boasted that they work on race car engines, so entrusted them with the work of fitting six new valve guides, de-glazing the barrels and nipping 0.3mm off all 12 valve stems to allow me some fatter shims and therefore extend the usable life of the head. When I came to collect the job, he had re-cut the exhaust valve faces and lapped in all the valves. I was also presented with an eye watering bill for £450 – about three times the damage I was expecting. When I got back to my workshop I realised that they had removed far more than 0.3mm from each stem and a few had so much removed that the top of the valve stem was beneath the valve keeper collets! I decided that at this point I had no option other than to carefully remove some material from the stem collets. To do this I very carefully clamped the collets in some extruded aluminium alloy soft jaws in the bench vice and removed some material with a hand file. This is not an ideal situation, but given how thin the original shims were this was probably the best solution. The important thing is that the bucket should act on the valve not the collets. I then refitted all the valves using the valve spring compressor, popping the collets in with my cranked nose forceps. Now the head is clean and sound mechanically it’s time to direct my attention to the aesthetics of the gargantuan mill in this mammoth bike, which will require me to get some serious muscle in to help remove the motor from the frame next month.