It's been ages since I last posted an update on my Kawasaki Z650 restoration. With rain every day since Christmas, sometimes all day and sometimes just for a short while, it's not been ideal working conditions.
But I've made progress on my secondary project of refurbishing one of the spare engines I've got, so the winter hasn't been totally wasted.
In the meantime, the last thing I did to the bike itself was to replace a faulty ignition coil. Sadly, it doesn't seem to want to start, which is a bit frustrating since it did previously.
Approaching it logically, there are only a finite number of things which could be the problem;
- Carburettors - unlikely, I've rebuilt them several times.
- Inlet manifolds - possible but unlikely. I put new ones on at the start of the process. However, they are just starting to show surface cracks, which is annoying and indicative of the poor quality of some of the pattern parts available nowadays.
- Compression - unlikely, I checked the compression just before Christmas and it seemed good.
- Timing. Possible, need to investigate.
- Electrical. The prime suspect ! Despite the new coil, the spark appears a little weaker than it ought to. It's definitely there, but orange rather than the blue it should be. Although I've re-made a lot of electrical connections already, I think the next job is to go through the ignition circuit thoroughly, cleaning it up and replacing anything which looks dodgy.
The first on the list was the engine kill switch.
In the manual, the right-hand switchgear is a single unit. It is treated as "replace if faulty". That was fine forty-odd years ago, but getting hold of a working replacement nowadays at a sensible price is incredibly hard.
Because it was treated as a sealed unit, individual parts were never available, and no-one currently sells a kit of refurbishment parts. It's something I might look into putting together, if I can find the specifications for each bit. In the meantime, it's going to be a case of taking it apart carefully, checking and cleaning each piece, and reassembling it.
First step is to undo the two screws which clamp the two halves of the switchgear to the handlebars. Note that the front one is shorter than the rear one. Both of these were horribly rusty, but cleaned up passably with the help of WD-40. I forgot to take a photo of this step !
This photo shows the switchgear gently moved open. The next step is to undo the screw holding the wire retaining plate and remove the plate, putting it somewhere safe. I gave it a quick clean, but it didn't need much attention, it's not a part of the circuit.
This next photo shows the plate removed, and the next stage, which is to undo the two screws holding the electrical contacts in place. These did get a thorough clean, initially with WD-40 and a good wipe with rag, and then some light sanding with lapping film on the top and bottom sides of the brass washers.
These are the actual contacts. They were in remarkably clean condition. They're also something I didn't want to risk trying to remove from the plastic retainer. After 45 years, it's likely to be brittle, and almost impossible to find a replacement if I break it.
So I gave them a good squirt of WD-40, then followed it up with an aerosol contact cleaner (which I think is mostly acetone). I made sure to use kitchen towel wrapped most of the way around the contacts in order to catch any over-spray. That stuff is pretty evil and would be likely to harm any chrome or paintwork it hits.
The next bit is easy; taking out the retaining screw which holds the engine kill switch in place.
This is the switch itself. The two screw holes at the bottom are where the contacts go, and the hole at the top is where the retaining screw came out of.
To open the switch up, the e-clip has to be taken off. This is a job to do very, very carefully, because it's very small and likely to spring off and disappear forever. In less confined spaces I'd use a small pair of pliers, but here I found it easier to push a 2mm watchmakers screwdriver into one of the gaps and twist it to get the clip moved so it could be pushed the rest of the way with a fingernail. Fiddly !
The switch opens to reveal a lower half with two contact points, and an upper half with a locating ball and a copper spring-loaded contact plate.
The idea is that the locating ball means that when the switch is turned, it has a "positive" feel to each of it's three positions. I have a feeling the ball should be spring loaded, but it was seized in and didn't want to go anywhere. When the plate is centred, the dimples on the copper plate are pressed against the contact points, completing the circuit and allowing the engine to run. Turning it either way breaks the connection and stops the engine running.
I cleaned the two contacts and the copper plate with WD-40 and then fine lapping film. I wanted them really clean, but didn't want to remove any more material than was necessary. The lapping film is 8000 grit, far finer than any sandpaper.
Under the copper plate are two tiny springs. These were in fairly poor condition, but a lot of the rust and corrosion came off with a soak in WD-40.
This photo is all the pieces in one place and after being cleaned up. The light was starting to fade, which is a shame because the copper plate and contacts were a lot shinier than the photo suggests !
After this, it was just a case of reassembling everything in reverse order. When the two clamp screws were tightened, it's important to remember to do the front one first, then the rear one. That means the switchgear is tightest at the front to stop water getting in.
The re-assembled switchgear isn't perfect because I couldn't put new parts in, but I think it's as good as it'll get with original parts cleaned. When it was all back together, I turned the ignition on, turned the switch to the "off" position and was rewarded with the sound of a quiet but healthy click from the ignition relay in the electrical box.
Next job is to go through the wiring to both coils, replacing any corroded connectors, followed by finding out how to test the electronic ignition pickup....
All photos in this post by me !