TRIUMPH TRIDENT
Last month, Peter Hatfield located a five-speed 750 triple in the United States and brought it back to Britain. Now it’s ready to take to the road which means he’ll really find out what’s wrong with it…
Last month, Peter Hatfield located a fivespeed 750 triple in the United States and brought it back to Britain. Now it’s ready to take to the road which means he’ll really find out what’s wrong with it…
After recommissioning the Trident I could now get in some road time. However, kick-starting the beast proved somewhat fraught. This refusal to start reminds me of Dave’s negotiating prowess. (Remember, Dave is my friend in the USA who brokered the deal – do keep up at the back.) When the vendor and previous owner was trying to start it for the customary test ride, he had the same problem starting it that I did. Every lunge on the kick-starter was met with Dave saying, ‘Each kick lowers the price.’
I digress. Eventually, the fires were lit and the road beckoned. When you’re fettling an unknown bike, you don’t want to go too far and you don’t want too much by way of traffic. The Somerset Levels are an ideal place for shakedown rides, and Wells seemed just the ticket, being some 25 miles distant from my abode. About ten miles into the ride, all was not well: the engine was lumpy, indicating a rich mixture. I made it back without breaking down, always a relief, and the following plug chop proved interesting. Cylinder one was very rich, cylinder two was just right, and cylinder three was lean. I think it fair to say that the carburation was out to lunch, and definitely a case of more carburettors being more trouble.
Back in the workshop (which sounds better than garage, which in turn sounds better than shed), the carburettors were removed, stripped, cleaned and various parts changed. I’d attended one of John Healy’s lectures on Triumphs and old bikes in general at the
Barber Vintagee Festival, and remembered his mantra aboout poorly-running Amal carburettors: ‘It’s the needle jet.’ Consequently, those were changed and new stay-up floats and aluminium float needles fitted.
After checking float heights and installing new sparking plugs, another shakedown run ensued, but the results were disappointing. I couldn’t dial out the richness on cylinder one. Not wishing any more wild goose chases on what were obviously worn carburettors, I decided to purchase a set of new 27mm Amal Premier Concentrics from Surrey Cycles, Burlen Fuels not having any in stock. Surrey Cycles had only the lightweight aluminium types, which, although at a slight premium over the more customary ‘pot metal’ zinc type, were definitely a case of less is more. Once installed and the slides synchronised, the carburation was spot-on.
Although I had done a pretty good job of eyeballing the throttle slides to ensure that they rose and fell together, I had ensured success by investing in a Carbtune gizmo. Along with sight glasses for reading the inlet manifold pressure, this natty carburettor balancing tool has rubber tubes that one pushes onto the inlet manifold stubs. Except the Trident doesn’t have inlet manifold stubs. But the kit does. And they’re threaded M5 and M6 – boo.
Out with the drill, and three M5 sized holes were tapped in the manifold ready for the adapters. (I reasoned that M5 would be best, just in case I messed up, in which case I could go to M6.) The adapters simply screw into the tapped holes, and the Carbtune
works by indicating the inlet pressure for each cylinder in the sight glasses. On a three cylinder machine such as the Trident, it’s best to adjust the two outer slide adjusters on the carburettors, using the centre as a benchmark. Once adjusted, the adapters are removed, and M5 socket screws inserted to plug the holes. I was lucky in that the socket screws I bought were the perfect length, and fitted flush with the inlet manifold.
I ran the Trident that summer without a hitch, and for most people that would have been sufficient. But I’m an inveterate fiddler and I wanted to add some reliability. Back in the day, Lucas electrics weren’t exactly the last word in dependability. Forty years on, the situation was hardly improved, what with modifications for electronic ignition, other assorted fixes, and old age. I had to admit it: the wiring harness was past its best. Simply replacing the harness would have been too easy. Also, my plans went farther as I wanted to replace the unintuitive Lucas handlebar clusters with their ‘up for right’ and ‘down for left’ indicator switches.
I’d previously bought a left side switch cluster from a Hinckley Triumph ST to use on my Street Triple, so that I could switch the headlamp on and off as I pleased – don’t you just hate headlamps that come on with the ignition? Having found that a self-latching relay worked well on the Street Triple to cut the headlamp when switching on, the cluster was now surplus to requirements. Perhaps I could adapt it to the Trident, a scheme that also worked with my idea to cure the wooden feeling of the front brake. It is well known that the master cylinder of 5⁄8” (16mm) is too large, and that something around ½” (12.7mm) gives more feel to the brake lever. With the Hinckley switchgear on the left, a matching Street Triple master cylinder with its piston of 14mm would be ideal on the other side of the handlebar. Thus it was that I decided not only to rewire, but also to change all the switchgear and front brake at the same time.
The first task was to install the new hardware. After all, if I couldn’t connect the clutch cable to the new lever, then the whole enterprise was doomed. Fortunately, the hole in the new clutch lever just required drilling to 3/8” (9.5mm) from the original 8mm, and I was able to use the standard Trident cable. The front brake simply required a new length of braided hose from the Street Triple master cylinder, and I took the opportunity to rid the brake of the horrible Bundy tube by installing a 70° banjo at the calliper. With the new controls working swimmingly well, I undertook the re-wiring job.
The first exercise when re-wiring from scratch is to plan everything down to the smallest detail. I had designed a main loom with two sub-looms, one of which was for generating the electrics, and the other for the ignition. I had decided to dispense with the stone-age technology that is the Zener diode and selenium rectifier, and replace those components with a Sparx regulator/rectifier. This lovely little unit has the appearance of a Zener diode heat sink, looks the part, and produces a steady 14.4V at most RPM. Wiring it up is simplicity itself: the two yellow wires are connected to the green/yellow and white/ green alternator wires, and the black and red wires are plumbed straight onto one set of terminals of the Motobatt MB9U battery.
I like these Motobatt units – they use absorbed glass mat (AGM) technology, which means they don’t leak acid, and they hold their charge very well during periods of no use. In addition, they have two sets of terminals, which means that not only do they always orientate correctly, but it is easy to add accessories without stacking up one set of terminals.
The other sub-loom was for the BoyerBransden electronic ignition. Having it as a sub-loom means that it can be replaced in future without butchering the loom. As it’s not an item that requires access, the Boyer unit was moved from its original location on the rear mudguard, and placed on the frame under the fuel tank.
For the main wiring loom, I had made a number of decisions: it was going to be negative earth, all the bulbs were to be of the LED variety, except the headlamp, which was to be H4 and switched via miniature relays living in the headlamp shell. The overall plan was to modernise, and that meant replacing the old glass fuse holder with a blade fuse box. Also, there would be no reliance on earthing to the frame; every electrical connection would go via a single earthing
point conveniently utilising the old rectifier mounting point, which was connected to the negative battery terminal.
So, what’s involved in re-wiring a motorcycle? Not a lot really. It’s mostly just a case of connecting the various switches via the switched live (white in standard Brit bike wiring) to the component and back to the single earthing point. For my set-up, the only complication was the Hinckley Triumph switchgear, as it didn’t use the old wiring colours and the cabling was too short to reach inside the headlamp shell. Armed with a suitable wiring diagram and a multimeter, I quickly figured out how each wire worked. I then grafted on new wires with the old standard colours to the Hinckley wires. To hide the joins, the wires were contained within braiding, which can fray unless sealed with heat shrink tubing.
With the electrics fettled for the riding season (yes, I’m a fair weather rider, and I make no bones about it), I looked forward to a trouble-free motorcycle for the summer. That was the plan. Unfortunately, plans don’t always pan out, as in: what’s that strange rumble coming from the primary drive, but disappears when I disengage the clutch?
Rather than simply tearing into the primary without any idea of what the problem may be, I sought the wisdom of the gurus on Triplesonline. The general consensus was that the problem could either be the primary drive cush rubbers, or more likely the rivets on the clutch end cover housing. To cut a long story short, it was neither. It turned out that the splines on the clutch plate and the drive hub were badly worn, soon fixed with new parts.
Now that the mechanicals, electrics and aesthetics were finally sorted out, I was feeling very happy with the Trident. Personally, I really liked the way it turned out, and I wasn’t the only one. Come June, I went on the Wells Motor Cycle Club’s Hare and Tortoise run, which was attended by many a fine motorcycle, including one pristine Kawasaki 750 H2 triple. I engaged in conversation with the owner, only because his rear lamp lens had fallen off and shattered into a thousand pieces while I was following him. We compared and contrasted our relevant bikes, which superficially were identical: three cylinders and 750cc, but there the similarity ended. There was a prize for the best machine on the run, and I thought it was no contest for the Trident, so I left prematurely. Had I not done so, I would have won the prize. Damn! Sometimes the grass is not greener.
It’s a shame that the buying public didn’t see it that way either back in the day. The world’s first super bike, in the form of the Trident and BSA Rocket 3, may have had fewer cylinders and less weight than its arch nemesis, the Honda 750 four, but it was quicker and handled better. All this brings us back to the original question: is less more? Probably. That is, if you ignore the vexed question of reliability, where less is...