KAWASAKI H2 C
Ralph again, but this time on his triple!
It seems some time since we last spoke about the myriad failings of my purple nemesis. I am now in a position to start re-assembling the two-wheeled smog monster.
My gearbox arrived back at Chez Ferrand with all the broken bits replaced with used replacements that had undergone a serious health check, so I should now have all the ingredients for a good robust cog-swapper.
To kick-off I fitted the upper crankcase in my home-brewed engine building frame and selected a nice sharp wood chisel to remove the remains of old base gaskets from the mouths of the crankcase.
I cannot over-emphasise how important it is to do this tedious job with maximum care and full concentration, as any chunks taken out of the gasket surface can cause leaks that would have a devastating effect on the good running of the two-stroke engine. After flipping over the crankcase, I started to repopulate it with all the gear changing components.
First back in was the shift drum and selector forks. It’s a fairly simple task, sliding the selector forks over the drum in their correct position as you push it in. Once the drum is in, you can engage the guide pins that follow the contours of the drum groove in each of the three selector fork bosses. These then can be tightened up and the tab washers flattened against the flats of their spanner hexes to prevent them undoing, which would likely destroy the box. Then the securing plate was fitted on the outside, followed by the indent lever that engages on pins on the end of the drum to ensure that the bike stays in the gears selected.
Before re-fitting the gear cluster shafts it is important to fit the bearing set-rings in the crank cases to prevent lateral movement. The outer races of the bearings have slots cut in them to locate into these rings. The outer races of the needle rollers, at the other end of these shafts, locate in the knock pins. It is slightly tricky to locate the selector forks in the gear grooves while simultaneously locating the bearings in their homes, but perfectly possible with a bit of practice. The clutch on this bike has a curious system of clutch actuation requiring two clutch push-rods. They meet in a bush behind an oil seal on the left-hand side of the motor. The bush is fitted at this point and uses a knock pin for location. If you look at photo 3 you can see the space for it. At this point I realised I had mislaid the smaller of the push-rods, but helpfully Kawasaki give the length in the parts book, so I made one up out of a spare exhaust valve for a Zed, which should be plenty hard enough and helpfully was the correct diameter – 7mm. I dropped the kick-starts gear in and the crankshaft, and carefully degreased all the
crank case mating faces on both sides with brake cleaner. Once happy that all the working parts were at their stations and there was no hint of grease, or any other detritus that could cause a failure of the seal, I buttered the mating faces with Wellseal, allowed it 10 minutes to flash off the solvent and then dropped the bottom case on. All the nuts and washers were returned to the studs and I broke out the torque wrenches: 3/8-inch drive for the larger studs and the smaller ¼-inch driver for the M6 studs.
The selector drum is actuated on the right-hand side of the machine, so the gearshift lever assembly has to go all the way through the crankcase to exit on the left for the gear change pedal. As it gets close to its final position the hooked levers that pull the shift drum around have to be gently located to the drum whilst feeding the return spring legs either side of their post protruding from the crankcase wall.
Once the gear selector gear was comfortably in place, I turned my attention to the diminutive clutch, which was woefully under-engineered considering the power output of the 750cc two-stroke powerplant. Compared with a Z1 it is like a toy and they have a tendency to slip under heavy acceleration, which is a shame as blisteringly rapid take-offs are rather the point of a big stroker. I fitted the various needle roller bearings, spacers, the clutch basket and the hub. I spun the nut up, fitted a universal hub holding tool and tightened the nut to the prescribed torque setting with my ½-inch drive torque wrench, which isn’t the easiest thing in the world to do on your tod, so I engaged the help of a gullible friend – cheers Gary!
Before refitting the clutch friction plates, I measured the thickness of their meat with my trusty digital caliper; they start out at 2.80mm +/- 0.1mm with a service limited of 2.5mm, so a measurement of 2.78mm meant there would be nothing gained by replacement.
Had I needed to replace them, I would have soaked the new ones in engine oil overnight before fitting. The friction plates have sprung steel rings inside them,
which I presume is to minimise clutch chatter. As with all multi-plate clutches, the steel plates are fitted alternately with the friction plates. The steel plates engage with the hub which is attached to the input shaft, and the friction plates interact with the outside basket, which is gear driven from the crankshaft.
Once the clutch is fully populated with plates one should ensure that one remembers to fit the longer push-rod, the ball bearing and the pressure plate pusher before fitting the pressure plate, etc. Some daft bugger may have forgotten the ball and pusher first time, necessitating a back-track. Once these components were in place, I was able to re-fit the pressure plate, noting that there is a mark on the plate which must line up with a mark on the clutch hub. At this point I decided to measure all
the clutch spring to ensure that they weren’t tired. They start life at 32mm and are considered to be scrap at 30mm, so mine were again in fine fettle. When I first stripped the clutch I had noticed that there were copper washers under the main steel washers over the springs, no sign of which was shown in any KHI (Kawasaki Heavy Industries) publications. I mentioned this apparent paradox on the Triples Club Forum and was told that this isn’t uncommon to add a bit more pressure on the plates to give the clutch a bit more strength, given how ‘under spec’ it is in the first place. I decided to re-assemble with the added performance clutch upgrade, particularly as the clutch had been working before the bike was stripped. I fitted the spring cups, springs, washers and M6 bolts before tightening them up to the correct torque setting. There was evidence of some form of sealant previously used to fit the actuator, so I cleaned all the mating faces up with some brake cleaner, and applied a small bead of RTV sealant before securing it in place with the original M6 JIS screws. I can now hear the siren call of a bottle of Hobgoblin so I will take my leave. I’ll tell you more about the purple pain in the pink next month.