KAWASAKI Z1325 Ralph Ferrand nears the finish line and makes a catch- tank.
Ralph moves on with more jobs on the big-bore Zed: this month a catch-tank and footpeg holders.
Last month I was fabricating custom parts for this indomitable 1325cc colossus of a Kawasaki based on a 1978 Z1000A2. The bike had been previously attacked by an amateur sporting considerably more enthusiasm than competence and the frame and running gear had to undergo some serious surgery to make this bike as safe as possible, considering the increase in engine power. One of the problems often associated with mono-shocking a motorcycle originally designed for twin shocks is that there is nowhere for the air-box to go. n this instance, even if there were, the original air-box, designed for a modestly tuned thou' with standard valves and cams, would probably not be able to provide the ow of oxygen req uired to feed an engine with a swept capacity of a third up on stock with massive valves and uber high lift cams. Given the lack of space left in the frame the only practical option was K& N pod lters or bell mouths. Bell mouths look the part and give little resistance to air ow to the hungry intakes, but are not choosy about what they suck into your engine. So K& Ns it was, which threw up another problem: on a standard bike or even car for that matter, the engine breather is fed into the non-ae ltered side of the air-box so that any oil smoke or mist is inhaled by the engine and burned in the combustion
chamber before exiting the exhaust. A big Zed motor has a chamber above its breather with bafø ing that discourages oil thrown about in the engine from going up the breather tube into the air-box, rescuing the vast majority back into the sump where it will do most good. What is left has to go somewhere and that somewhere is a catch-tank. Back in the day it was seen as pretty cool for a race bike to have a breather pipe pushed into an empty beer can cable tied to the bike. Given how much more clean living today' s youngsters are than we were, they would probably favour a mineral water bottle or to be really risquè , a Red Bull/ Monster Energy can. This build was supposed to be a uality custom motorcycle, so there were not to be any cable tied beer cans! n an ideal world one would buy one of the myriad catch-tanks offered to car and bike tuners on ebay, but sadly, given the limited space available, had to design a custom tank to t in the very limited free space. chose to make it out of stainless steel which would last forever and is reasonably easy to fabricate. bought a piece of suitable austenitic stainless steel tube, but it was too long by a fair margin, which was good in that it gave me some spare stock left for the shelf, but did provide me with the problem of cutting it to length, squarely. f had a giant lathe with a 4in+ spindle internal diameter would have cut it as accurately as possible with a hacksaw, probably a power one if had room for a very large lathe and then stuck it in the three jaw chuck to face off, happy days! rom memory, the piece was 100mm diameter and given the hole in my lathe chuck, the only way could grip it was with reverse jaws i.e. gripping the inside of the hole (see photo). Because one end was pretty square to start with this was okay, but not to take any heavy cuts with a hugely out of square workpiece. Being extremely careful, (and am NOT advocating this as good workshop practice let alone within the realms of good health and safety) set the spindle turning and gingerly held my Dremel with an abrasive cut-off disc against the rotating workpiece which acted as an abrasive parting off tool. Most importantly this gave me a nice and square cut. was then able to very
gently face off the end with a tungsten carbide tipped tool. then took the work piece out and faced the other end. Sometimes you need to think outside the box if you don' t have all the workshop eq uipment you desire. f you are ever maverick enough to use an abrasive on a lathe, always ensure that you cover the lathe' s bedway with cloths and give them a very thorough clean afterwards or you' ll cause irreparable wear. then turned my attention to the top and bottom pieces. The bottom was a simple circle and the top needed to have two lugs sticking out to support the tank from brackets would later weld to the upper frame rails. have found the easiest way to cut stainless plate is with a hand electric jigsaw using a very ne tooth bi-metal blade at fairly slow stroke speed and no pendulum action. nless you have a limitless source of good uality jigsaw blades, it is imperative to use some form of cutting compound or uid. With my jigsaw always use Rocol RTD cutting compound that doubles the blade life, though experience with cutting stainless sheet tells me that the blades last almost no time without some cutting uid; even engine oil is better than nothing. Don' t use a cheap jigsaw without proper bearings and speed control or you will end up in a mess. The difference in cost between a cheap, crap power tool and a professional one is not a good saving, if you' re working at anything for that basic home DI . Once cut out, clamped the top in place on the tube in the bench vice and fettled the contour to the tube with a good uality sharp ne hand le. When cutting austenitic stainless steel it is crucial to use good uality sharp cutting tools as the metal work hardens. sing a dull edge will actually harden the piece instead of cutting it. welded the top in place using my TI G welder set on DC (Direct Current). To ensure that it was leak free inverted the piece and sat it on a piece of paper wipe and half lled it with water. Were there any leaks it would show up on the tissue after a while. There were no shows, so no leaks. Back on the lathe machined up a threaded boss and a hex headed drain plug in stainless steel. used a nice ne metric thread and tted a bre washer to the drain plug. drilled two holes in the tank for the inlet and outlet pipes and cut two pieces of stainless pipe for the inlet and outlet stubs and faced them off in the lathe. used the mighty TI G welder to glue the boss to the bottom, welded that to the bottom of the tank and welded the inlet and outlet stubs to the container. At various stages in the manufacture polished the tank on the bufae ng spindle and while it' s not easily seen on the nished bike, like all details to look the part. t didn' t take that long and removed all discolouration from the welding processes. As a late addition to the project the bike' s owner decided that he might be able to coerce some gullible young(ish) lady to take her life in her hands on the back of this re breathing mechanical Welsh Dragon and so asked that add rear foot rests. The original footrest hangers had been chewed off years previously so had to make something new. The brief was
that the foot rest hangers were to be removable and not to add excess weight. We decided on original pegs and suggested that these could be supported by hangers fabricated from 6mm aluminium plate bolted to bosses welded to the frame. kicked off with a template made from packaging board, cut out with hole positioning clearly marked. offered this up to the bike and felt that it looked in keeping with the overall design and the owner was happy. To cut a strip off the big sheet of 6mm aluminium plate clamped up a straight edge as a guide and used a thin bladed cordless circular saw. then applied marking blue to the top face and transferred the template contour and hole positions with a scriber. Once fully marked out used some bi-metal hole-saws in the bench drill to cut out the lightening holes. When using hole-saws, where possible, it' s best to cut halfway through and then ip the material over and nish the cut from the other side. That way you avoid getting burrs and the scrap bit in the middle is easier to extricate from the cutter. also drilled the mounting holes at this point before cutting the nal shape out on the band-saw. used hand les and emery cloth to nish up the edges. To make the mounting bosses grabbed a suitable diameter piece of round free cutting mild steel bar from my stock and put it in the lathe. faced off one end, centre drilled it, pilot drilled it and drilled deep enough with a 6.8mm drill (tapping drill for M8 x 1.25) to make four bosses allowing for facing and cutting. then tapped the hole M8 as deep as was practical; was never going to be able to cut the full depth in one go. then put the bar in the bench vice and sawed off enough for one boss. took this piece back to the lathe and faced it off with a knife tool to the exact length sought. also faced off the main bar again and cut the threads a bit deeper and so on until had all four mounting bosses. sing bolts and lock nuts secured the bosses to their respective footrest hangers and clamped them in position to the frame with G' clamps. t was important to t the hangers to ensure that the mounts were in exactly the correct position. sing my trusty TI G plant welded as far around each boss as was possible before removing the footrest brackets, allowing me clearance to nish welding all the way around. Next month ll kick off by repairing a severely buggered side-stand mount as the last job before the frame and other bits go off for powder-coating.