❙ KAWASAKI Z900
Kindly given a box of old Zed bits, Ralph Ferrand is back on the case with one of his favourite four-strokes!
Ralph Ferrand is on part one of this stocker restoration.
Right now I’m the envy of my Zed Head friends, having been the lucky recipient of the extremely generous gift of a collection of boxes containing a 1976 Kawasaki Z900 from a fellow member of the Z1 Owners Club.
I gave my word that I would perform as good a restoration as I am able to and have been throwing money at the project from day one. Although the bike is mostly apart, the bottom-end of the motor was in one piece so it was time to pull that apart.
Many years ago I designed and made an engine building stand to hold bike motors whilst they are disassembled and rebuilt that allows the engine to be turned though 360 degrees. This was with an eye on selling them on, but with the top-quality parts I was using, they would have cost an arm and a leg. Sealey has just produced a new engine building stand and they sent 1 1/ Using mechanical advantage to get the heavy engine unit into the engine frame. The engine securely held in the Sealey engine frame. The inner clutch basket is held with a universal clutch basket holder whilst I remove the securing nut with my air impact wrench. me one to try out. Engines don’t come much heavier than a Z900 lump, so it seemed like a good test. It turned up flat pack and was easy enough to put together. I tied lifting straps to the engine and attached them to the lifting arm over the top of my bike bench. I dropped the bench down, leaving the engine hanging from the arm. The engine building stand was placed on the bench and the platform brought up to the suspended engine. I lined up the arms of the stand with the top crankcase engine mountings and bolted the arms up to the crankcase. Once fully secured I raised the bench so that I could remove the lifting slings. It has to be said that the stand doesn’t have the rigidity of my own version, but will do the job allowing the engine to be rotated through 180 degrees, and is good value at £165.54.
I removed all the clutch plates and attached my universal clutch basket holding tool to the inner basket. Because I have the facilities, I fitted a big socket to my Aircat super powerful air impact wrench which whizzed the nut off securing it all to the gearbox input shaft.
Because the engine was going for a deep clean everything had to come out and the next ball of fun was to remove all the cylinder studs. After soaking the bottom of the studs in ACF-50 for a day or two I locked together two M10 x 1.25 pitch nuts on the top of the studs. For those that were resistant to being extricated, I heated the crankcase part they’re secured in with a heat gun and for those most problematic, my propane torch.
I soon realised that the alternator rotor was wobbly. This is a common problem and whilst one could engineer a solution given enough time, there is little point given that Electrex World make a fabulous replacement. I used a pin wrench to hold the rotor on the crank whilst I released the securing bolt with a cranked ring spanner.
I then used a basic six-way flywheel puller to release the rotor from the taper. Because there is a bolt hole in the end to anchor the rotor, I put in a round piece of metal against the end of the crank for the puller to push against. Once the puller was screwed in tight a gentle tap on one of the arms with a soft-faced hammer was all that was required to release the rotor, being careful to stick the woodruff key somewhere safe. I removed the transmission cover which had previously suffered the indignity of having a drive chain snap; a common issue in the past when people used split links as they’re easier to fit if you don’t have the tools to rivet up a chain and can’t be arsed to remove the swingarm to fit the endless chain as was fitted originally. As always, the hardened bush behind the front sprocket was worn by the lips of the oil seal with fine grit flicked up from the road by the chain, and was added to the long list of genuine Kawasaki parts needed.
I next dropped the sump off and it was full of truly hideous crap from the oil that had festered for many a year. Plenty of degreaser was used to clean it and finished off with copious amounts of brake cleaner squirted from my chemical spray bottle and blasts of compressed air.
I loosened all the crankcase bolts with a breaker bar. A few wanted too much torque so I used the propane torch to warm up the part of the casting where the bolts were threaded in and dribbled in some ACF-50 which is really great for corroded aluminium alloy and is the best of all penetrating oils I have used. Despite this care, one of the really long M6 bolts snapped. This isn’t uncommon particularly with the long bolts from on top around the final drive area; they’re often knackered by being stretched by home mechanics who don’t use a torque wrench. The crankcases already had a number of snapped off screws and bolts for me to repair. Once the bolts had all been loosened, I whizzed them all out with the cordless impact driver Sealey gave me to test a while ago; so much quicker and easier than a ratchet. The crankcases have some M8 threaded holes into which bolts are screwed to push the two halves apart. These were seriously crusty with years of corrosion so I lubed up an M8 tap and cleaned them up. Always check, double check and then check again that you have removed all the crankcase bolts before even thinking about using these. I had a fellow who had missed some bolts and absolutely creamed these bolts in and smashed the front of the crankcase. That was another set of Zed crankcases that would never be used again. Once the crankcases were split, I carefully put all the parts into storage boxes and labelled plastic bags ready for the rebuild.
As with almost every Zed I have come across, someone had snapped off one of the four final drive cover screws. I have repaired them on a bike and it is a right royal pain in the botty. I left this one until I had the cases split for minimal grief.
21 21/ For the best chance of an extraction I broke out some more ACF-50 and the propane torch. 22/ The extractor was inserted in the hole and then I carefully turned it anti-clockwise to extract the screw.
The one that had gone was one with a dowel, which always adds another level of difficulty. The dowel was well stuck in, thanks to galvanic corrosion common with steel components in aluminium alloy castings. I made life easier with the application of some direct heat through the medium of my beloved propane torch and a drop or two of ACF-50. Once out, I fitted a tool maker’s button in the hole to centralise the drill. I drilled it with a left-handed drill bit and then used a screw extractor to remove the remains of the screw. I used a left-handed drill because it’s not unheard of for the screw or stud to unscrew when the drill bites and generates a bit of heat; worth a punt. Once out, I fitted a Helicoil, not as a repair but as an upgrade to prevent further issues.
The bolt that snapped off flush with the face of the crankcase could not be removed in the same fashion, so I centre punched the remains in the middle. I then set the crankcase up on the bed of the pillar drill and centre drilled it to get accurate position. I then drilled down through with a nice sharp 3.2mm top-quality twist drill to ensure the best chance of a nice concentric hole. Old, worn or cheap drills can wander, which is the last thing you need removing broken fasteners. As the old adage goes, ‘Buy crap tools and stuff the job up’.
Never use cheap easy-outs for extracting screws or studs; they rarely work and often snap off. leaving you with a piece of high carbon steel to remove and the only way that’s happening is by the expensive and inconvenient visit to one of the few engineering companies who still have a spark erosion machine.
Before starting the extraction, I again applied some direct heat and some ACF-50 with the propane torch to make things safe.