OK, what is the name of the switch? Is it an ignition switch? On the bike you put in the key and turn it and it powers up the bike. You push the start button to actually cause ignition so the key switch is the power switch. I'm going to call it the ignition switch anyway.
Any hoot. I was finding that the ignition switch was getting dodgy. Sometimes It'd turn the bike on, sometimes it wouldn't and then by fiddling with it I'd get the power. When it was really getting to be a pain it was time to fix it.
Not knowing the mechanics in detail - or at all, I tried the old WD-40 in the lock. It didn't seem to make any difference. I looked on the internet - they say "Don't ever use WD-40 to clean contacts - it stay wet and attracts dirt and dust and the all things unholy". Woops I thought! Another blog said repairing it was an easy job so I thought i'd do the job myself - and I did. So here's what I did so that you can do it to, and I'll be able to do it in ten years when I've forgotten all about it.
Step naught - you need security headed screwdriver - a small star shaped one, some emery paper or whatever to clean the contacts, a sharp knife, a small cable tie (or equivalent), a rag to clean things up, Spanners to remove headlamp, medium sized flat headed screwdriver to tease the switch apart... and some common sense.
Step one - remove the headlamp and it's casing. This is described in another blog on this page.
Step two - remove the speedo and rev counter. Well actually this is what I did since It gives your a bit more light to see what you're doing - but it also means they are flopping about all the time and getting in your way. So next time I do this job I think I'd leave them attached and then only remove them if they're getting in the way for some reason. If you want to remove it's a simple job of undoing the two chrome bolts either side of the ignition lock.
Step three - unscrew the three small screws holding on the ignition switch. These small screws need a "star" headed screwdriver to get them out. I got a security screwdriver bit set which had many fun looking screw shapes along with a selection of different sizes star shapes. Luckily these star heads work at a bit of an angle which is useful since there's not much space. Once unscrewed the switch should be easily released by pulling down. When it's off make sure you note the position of the switch (e.g. the position of the slot) for when you replace it. Note the slot is keyed and can only go on one way round. At this point I realised why squirting WD-40 in the lock had no effect on the switch. It's pretty well sealed and none of the WD-40 got anywhere near the insides of the switch.
Step four - remove the plastic cover - just pops off.
Step Five - cut off the plastic cable-tie holding the wiring to the switch case.
Step Six - Remove the switch case. Now this is where a bit of vandalism came into play. The plastic casing, getting on for 20 years old is a little brittle and there was no way it was going to let me pop it off without shattering the casing. So I used a sharp knife to cut two little slots into the casing so that the sides could be pulled apart allowing the casing to be pulled off. (The casing has two bulges on either side into which lugs on the switch base extend holding it all together.)
Step seven - carefully pull the switch out of the casing and be ready for a couple of spring loaded ball bearings. In my case the balls stayed in place until later when I knocked one and it pinged off. Luckily it didn't go far. So just always be aware the bearings could escape.
Step eight - Invert the switch (e.g. the base (with its wires) is on top). Tease the plastic switch gubbins (e.g. the thing with the ball bearings and copper contacts inside) off of the switch base using a gentle turn of the screw driver.
Step nine - clean everything up. I used fine emery paper to clean the spring loaded contacts in the plastic holder and also those on the switch base. You should then lubricate it with a little bit of the right sort of grease. Not sure what it should be and didn't have any to hand so I didn't bother - time will tell whether that's a good idea or not.
Step ten - put the switch back together. Keeping it inverted, carefully push the plastic holder into the base making sure the contacts and ball bearings stay in place. Push on the casing - should just click on. If you managed to break the case a bit when removing it and one of the recesses has gone, as long as it's mostly there you might still be able to use it since the three screws should hold everything together when it's on the bike.
Step eleven - pop the case cover back on and just to try and keep it all water resistant, I put some electrical insulation tape around the unit so that the cover was held on and the slots I cut in the casing were sealed.
Step twelve - cable tie the wiring from the switch to the switch casing, In my case I didn't have an appropriate tie so I used some thin wire which I twisted on to hold it all tight.
Step thirteen - Put the switch back in place and screw it in with the three screws. You might have to wiggle the ignition key in the lock to get the switch and the lug from the lock to align, but it should be pretty easy.
Step fourteen - replace the headlamp (and speedo if you removed it) and off you go!