The Light Pours Out Of Me


As noted in my last post, I’ve been having a few problems with the lighting on the TRX. I decided to do something about this in time honoured tradition, by just doing the first thing I thought of, rather than doing a bit more thinking. So, I went out, and bought a headlight unit from an entirely different bike, on the offchance that it might work. The first immediate problem was the connector was obviously different, but more importantly, about 30 seconds after plugging stuff in, a quick bit of mental arithmetic showed me that I’d be pulling pretty much double the current through the aged wiring and handlebar switch. I could ‘do the math’ as the saying goes, but I’m not going to do that. I’m going to do the maths instead. It’s a small distinction, but an important one, I think you’ll agree. So, the standard H4 bulb draws 60W on main beam, 55 on dipped. So, with a 12V supply (give or take – I’m not planning to land a probe on Uranus or anything like that, so I don’t mind being a few % out either way), that will draw 5A on main, and about 4.6A on dipped. The new headlight has a pair of odd P30T-40 bulbs, which are 55W main, 40 dipped. Each. So, that’s about 9.2A on main, and 6.7A on dipped. A pretty substantial increase in current draw. So, it was immediately apparent that to get the most out of the new light, and to prevent the handlebar switch melting, I’d need to add a relay. Better than that, I’d add two – one for dipped, one for main beam.

A quick visit to the Vehicle Wiring Products website soon relieved me of another twenty quid or so, but in short order a large envelope turned up with everything I needed – a pair of relays and connectors, some wire, a couple of fuse holders and some relay sockets. For this job, I only needed four pole relays – which is handy, as they’re a couple of quid cheaper. First job was to decide where to mount them on the bike. You can put them next to the fusebox in the seat unit, but I decided to run them at the front of the bike, attached to the fairing mount bracket. This simplifies the cable run a little bit, but more importantly, makes them easier to get to when I undoubtedly break one of them. Five minutes with the drill, and the sockets were mounted.

Now, at this point, I should probably draw a nice little wiring diagram to show you how to wire the things up. Only I’m not going to, as I’m terrible at drawing, and there are already a million nice diagrams drawn by people who are far better – just google ‘headlight relay wiring diagram’ and look at the pretty pictures. Now, one notable short cut that I took was to wire a single fuse in place, rather than a pair – one for main, one for dipped. This means that if the fuse fails, I’ll lose all my lights, as there’s no provision for a sidelight with these lights either. No worries though. As has been determined already, I’m quite used to riding around without any lights at all. Anyhow, with the sockets mounted at the front, some nice fat cable was run from the battery directly to the live side of the relay, and the existing bulb holder was hacked off to wire the existing high and dipped feeds into the switching side of the relay. It was about this time that my soldering iron exploded. Literally. I was using a gas powered iron, and after many years of faithful service in the paddock, it finally shat itself and blew the end off the gas reservoir. Good job it was pointing away from me at the time, as it went a good 5 metres, bounced off the wall at the far end of the garage, and landed back at my feet.

So, where were we? Oh, yup. Relays wired in, cabled up, so just needed to physically fit the headlight and plug it all in. And in a surprising turn of events, it worked first time. So, is it any good? Well, most of my riding at the mo is being done on some pretty busy roads, so I’ve not had the chance to test it yet on a completely unlit, empty road. But initial results are pretty positive for sure. The beam pattern on dipped is noticeably wider, and there’s definitely a lot more light coming out of it. So all in all, I’m calling that a bit of a success. Total cost was about £75 or so, for the light, and the relays and stuff. I probably could have saved about 50p by reusing some old cable, but I decided that it was worth buying some new stuff. Oh, and I suppose I need to buy a new soldering iron now too. Dammit. Just as importantly though, the twin projector headlight just looks so much better than the old unit. I’m going to keep the old one, just in case the new one falls foul of an MOT law at some point. As long as I wire in a decent weatherproof connector, it will be a 10 minute job to swap them over.

Now, it’s worth pointing out that I’m painfully aware that blogging is now *so* 20th century. And to be fair, I did start this one in 1997. But, as my children have pointed out before, vlogging is where it’s at now. So, with that in mind, and because it’s easier to just set up a video rather than take a million photos, here’s a couple of quick videos explaining some of this stuff. Firstly, the why?


And, of course, the what?


I was going to do the how? but the battery died in my camera. If anyone is even remotely interested in watching me burn my fingers with a soldering iron for 20 minutes, I’m sure I could be persuaded to do something along those lines for another project. Alternatively, I’ll just resort to my 20th century ways, and take a load of photos.