KAWASAKI H2 C
Ralph seals the deal with his H2!
In my life I have always considered two-strokes to be trouble and in my experience the more pots, the more trouble; ergo triple trouble delivered by the purple pestilence!
The last job to do in the engine build frame was to refit the check valves at the bottom of the crank cases. These were an idea Kawasaki Heavy Industries dreamed up in 1974 for the H2B onwards in an effort to do something useful with any oil building up in the bottom of the crankcase when the bike has been idling or slow running, and to attempt to reduce the noxious smoke cloud from the exhausts when one is back on the power. When the engine revs up again crankcase pressure increases, forcing the oil into drillings at the bottom, which then feeds oil into the one-way check valve and then into the left-hand main bearing of each individual pot. The mica petal one-way valve and the constantly changing pressures in the crankcase effectively make this a scavenge pump. This has the effect of increasing lubrication on the bearing and then makes it easier for used two-stroke oil to join the swirling air/fuel mixture headed upstairs to the combustion chamber.
Reading the busy forum on the Triples Club, where there are some seriously knowledgeable folk, it seems that the general consensus is that these valves bring little to the party and many owners deem it best to block them up. Given the originality of my bike I want them back where they should be, given that anything non-standard would negatively affect the monetary value of the Purple Pain.
Having had them re-plated in bright zinc plate, as they were when I bought the bike, I have now discovered that they should have had a yellow/gold passivate! I took plenty of pics as I disassembled them for my articles, so I checked back with them to make rebuilding them a piece of urine. For those not writing about their endeavours, can I suggest you use a smartphone to archive the strip; though if it ends up as disgustingly filthy as my trusty DSLR you will need to clean it regularly! I re-used the gaskets which were in good condition with a smear of Wellseal.
Because I found it slightly tricky extricating the motor from the frame in its entirety, without chipping paint on the down tubes, I decided to make life easier by not putting on the outer casings or top-end before replacing the engine unit, particularly as I didn’t have a spare pair of skilled hands available. Having nailed the clutch back into place, it was now time to re-home the lump. I protected the painted frame parts with workshop towels and then slid a bit of gash MDF over the bottom frame rails. I built up a platform under the motor in the engine building frame with wooden blocks so that when I removed the
securing bolts it wouldn’t fly to the floor under gravity. It was then straightforward to lift the power plant from the bench and slide it on top of the MDF in the duplex cradle.
Because I was working solo I attached a piece of rope around the crank on the left, up through the tie points of the lifting arm above my bench and back down to be tied off on the clutch basket the other side. I then dropped the bench down a little bit so the rope took some of the weight of the engine, allowing me to get the MDF and towels out the way.
With the engine partially supported from above I was then able to nudge the engine into its final resting place without fear of trapping my fingers. Had the engine unit been any heavier I should have found more suitable lifting points, but for this particular application the low loads being applied were not a worry.
As someone used to working on Kawasaki’s four-stroke multis, I have been less than enamoured with the build quality of the triple compared with the Z1s; they were clearly built to a price.
With the motor in place the engine seemed somewhat narrower than the frame at the mounting points. I measured the ‘slop’ and then searched around my washer collection to find washers to act as shims to pack out the gaps at the engine mounts. From memory I think that the gap
was 1mm. Disappointing, when I have worked on so many big Zeds where the rear of the crankcase fits into the frame cradle as tightly as an otter’s pocket. I had all the mounting bolts re-plated with bright zinc for that new look.
With the lump safely ensconced in the warm embrace of the widow-maker’s frame, I noticed that I had forgotten to fit the oil seal for the gear change shaft. Oil seals are designed to keep the allimportant lubrication fluids where they should be when you have shafts passing through the walls of the component containing the lubricant; in this situation it is the gear box.
There are various different types of oil seal, but the most common are like the one in the diagram I have drawn. The body of most oil seals used on bike engines tend to be manufactured from nitrile rubber, which has good resistance to heat, petroleum and hydraulic oils as well as petrol. Nitrile is designed to operate from -40°C to 120°C and if your engine is any hotter than 120°C then you will have a lot of issues. On the most commonly found seals you have a lip on the very outside of the seal which just touches the shaft and whose reason for existence is to keep dust and grit away from the delicate inner lip.
The inner lip is held in contact with the shaft periphery by a spring steel garter, which is effectively a toroidal spring which exerts an even, but gentle force on the lip: when a seal is holding back oil around a constantly turning shaft like a crankshaft or gearbox shaft it is of paramount importance that shaft has a perfect ground finish, otherwise the vulnerable seal lips will be abraded by the spinning shaft generating heat. For the same reason the seal lip needs to be lubricated by the oil behind it.
Where there isn’t great lubrication the seal will not only be damaged, but rather counter-intuitively will wear a groove in the shaft, particularly if the shaft isn’t case hardened. Although the lip parts of the seal need to be nice and flexible, the outer body needs to be rigid. This is achieved by having an L-section steel support. When the seal is drifted into its cutaway the steel reinforcement causes the interference fit of the outer body to be held tightly in the seal’s orifice, preventing movement or leaks around the seal.
Whilst I will not compromise on quality materials, parts or tools, I am not partial to being ‘bent over’ just to have a part in a box with an OEM (Original Equipment Manufacturer) logo emblazed on the side. Kawasaki, Yamaha, et al do not manufacture oil filters, seals bearings and the like. When they design an engine they will look at the space available and then
seek out an oil filter, bearing seal, etc., that will fit the space and specification. They then buy loads of them for a very great discount and get some boxes printed with ‘Genuine Kawasaki Part’ and then mark it up in price.
So, with oil seals and bearings, it is always worth measuring up the original and getting a price from an industrial bearing supplier. Bearings usually have their size and type engraved on one side of the outer race.
A word of caution though; not often, but occasionally I have found the bike shop cheaper, e.g., a clutch bearing for SWMBO’S Street Triple cost me more from a local bearing supplier than it would from the main dealer, had they had stock! In the case of the oil seals for my smog monster, however, a goodly saving was made with an order from Simply Bearings, who seem to have limitless stocks and with bearings will usually offer you a choice of manufacturers and quality levels.
As I had to fit the seal over the shaft, I needed a drift with a hole that would push the seal at the correct position and would not be impeded by the shaft. As is often the case, the near perfect tool for the job was a deep reach socket. Rather annoyingly, I hadn’t noticed that some bell-end had hit my casing around this oil seal, making the oil seal cavity somewhat less than circular. Had I noticed this before I nailed the box back together, I could have repaired the unnecessary damage without too much difficulty. With the engine back in the frame, waving propane torches about is asking for trouble, so I decided to hope and pray that the seal would reshape itself to the strange contour of its new home and all will be well with the world.