KAWASAKI Z1325
There’s set up, a rotten rotor to sort and then a test ride: the mighty Zed is finished!
It’s finally finished!
At last I am on the final furlong of what has been a substantial build for me. I have to say that I have enjoyed many parts of the build, though not others!
Heavily customised bikes aren’t for me, but I do rather enjoy the challenge of building them. I love designing and making custom parts. What I am less keen on is sorting out other people’s screw ups! I really hate telling the owners of classic bikes that a previous person/owner has done bad things to their bike and it will cost a lot of money to put right. And so it proved with this bike on a few occasions. So, the mighty Mikuni 34mm flat slides were pushed into the lovely new supple intake stubs ready to start their life of accurately metering the go juice and life-affirming oxygen through the oversize valves, opening far wider than Mr Kawasaki ever intended into the massive oversized combustion chambers to be compressed and exploded, forcing the high compression Wiseco pistons down at time warping speed making huge amounts of power to be transferred through the very wide rear hoop to the glorious tarmac of south Wales. (Editor’s note, you can tell Ralph is paid per word…) The genuine K&N pod air filters needed a finger of red rubber grease before they could be persuaded to take their place on the air intakes of the flat-slide racing carbs. I removed the oil pipes from the top of the oil cooler so that I could fill it with oil to help it along. I used one of the dear little funnels I usually use for filling lead acid batteries with distilled water. After the first fill this step is unnecessary. The oil pipes could then be secured in their final positions. I then fitted the fuel pipes to the carbs using the supplied fuel pipe and clips. If this fire-breathing motor was going to be used for racing and every ounce of power had to be extracted from it, I would have encouraged the customer to heavily invest in a Dynatec 2000 ignition system which is programmable using a PC, but such extravagance and the dyno time involved in setting it up is wasted on a
road bike. Rather I suggested the Dyna S system, which I use on the vast majority of my own bikes. It’s a piece of cake to fit and is hugely reliable. The only downside is that it uses the bike’s original mechanical advance system using bob weights thrown out by centrifugal force and controlled with springs. As the springs age they tend to weaken and the engine ignition can advance before it should. I have had this issue with my own Zed for over 12 years, but she keeps going and I never seem to be able to find the time to change the springs! I decided to statically time this engine before firing her up. I dug out a pilot light bulb and holder, and connected the bulb to the black wire from the Dyna S and the other to ground. Using the timing marks on the advance mechanism and the mark on the crank case, I moved the crank so that 1 and 4 was at the full advance point. This is the mark approximately 12mm to the right of the ‘F’ mark, which denotes the firing position at full retardation. I then turned the ignition on, loosened the screws holding the Dyna pick-up plate, turned the rotor clockwise to its fully advanced position and then moved the plate until the light was coming on at this exact spot. It’s worth moving it back and forth a few times to get the exact spot. I then locked off the securing screws and moved the crankshaft back and forth a good few times, with the rotor held at full advance to ensure that the switching was happening precisely at the full advance mark. Just for belt and braces I re-performed the same process on 2 and 3, but they were perfect. I have yet to
have a Dyna S plate where they are not correct, but it’s worth checking. Once the engine was up and running, I checked the ignition dynamically with a strobe timing light and no adjustment was required. With the engine warm I turned my attention to synchronising the carburettors. The adjustments of the slides are rather confusing if you’ve not done a set of flat-slides before, and I hadn’t! With every other make I have come across you slacken off the lock nut and adjust the centre screw, but with these carbs the screw is the lock and the nut is the adjustment. This messed me around for quite a while until I gave up and did what I should have done initially – RTFM (Read The Flipping Manual)! Because I needed to get a screwdriver through the socket, I had the chance to use my rarely used drive through Signet Vortex hollow socket set. I could probably have used a cranked ring spanner, but I paid good money for that socket set and like to get some value from it. The slides in these carbs rattle, making a lovely clackety clack noise so no one is in any doubt that the bike has racing carbs! The carbs have their own vacuum take-offs which I connected to my Vacuum-mate to balance the carbs in the normal way. I won’t go into this again as I have covered it pretty recently on another bike. After a short while of running there was a very unpleasant and definitely not racing sound coming from the alternator, so the mill was stopped and the casing removed. Oh my God! I had known that the taper was a bit rough, despite the crank having been sent to a specialist crankshaft builder who dynamically balanced it. The brand new rotor had come loose from the decidedly not brand new taper. There was only one thing for it. Other than stripping the motor and getting the taper re-ground, that was to lap it on. I applied fine grinding paste – of the sort used to lap valve seats with – to the taper and replaced the rotor loosely. I turned the rotor on the shaft alternatively clockwise and anti-clockwise, applying a pressure so that the tapers would be lapped together. Every so often I would remove the rotor, clean both parts and apply a bit of fresh paste, because (like emery cloth) it gets worn down eventually and the abrasive grits break up. By inspecting the parts at each removal, I could monitor the progress. I applied some engineer’s glue to the taper inside the rotor and refitted the rotor dry, which gave me an idea of the improvement. Initially it was mainly high spots, but as the lapping progressed, so more area of the tapers were in contact with one another. Once I was satisfied that the tapers were good enough, I applied some anaerobic high strength retaining compound to the tapers and finally refitted the rotor, which then stayed on securely. We managed to source a rather nice light aluminium custom chain-guard for a GSX-R1100 and I made up some brackets to fit it as the supplied bits didn’t work for us. The paint set came back from Andy Marsden at Ultimate Bike Paint near Bristol. It is a lovely candy blue and gloss black. The photographs do not do credit to it. The blue really pops in the sunshine. I am very tempted to get Andy to paint one
of my bikes the same. As always I had to clean out the threads for the tank badges with an M3 tap, before screwing the new pattern badges sourced from Z-power. I’m always nervous about handling new unblemished paint work, as the slightest slip can spell expensive disaster. The owner of the bike had bought a new replica rear mudguard for the project, but because of the massive width of the rear wheel it really didn’t work so I swapped him for a tail tidy I had bought from Z-power for my Z900A4, but had changed my mind about. It was perfect for this bike. The number plate, however, was not as visible as it should have been as it was being masked by the tail light, and as the Welsh Police are notoriously hot on such infringements, I made a board for it out of sign-makers’ laminated fibreglass and aluminium sheet which is very strong, but light. For neatness I decided to bond the number plate to it so there would be no screws. I painted it black, but masked the portion where glue was to be to get a better bond. It was finally finished and I took it for its MOT, which it sailed through. Riding was impressive. Even though the engine was brand new and needed to be run in before having the fuelling set up on a dyno, I was very pleasantly surprised how hard it pulled with a strong eagerness to rev out. Following the advice proffered by Kawasaki drag racing ace, Tim Blakemore, we plumped for the 34mm flat-slides which gave it oodles of low down grunt, making it a joy to ride on the road. The sound coming from the Delkevic pipe was awesome. Now it was time for me to give it back to the man who had paid so much of his hard-earned for the bike to be built, and I have to admit I was sad to see it go.
Thanks to:
■ www.bikerstoolbox.co.uk ■ www.ultimatebikepaint.co.uk ■ www.z-power.co.uk