tech26

Well, it's Triumph time, again. Thanks to our former president, Barry Smith,
I have ended up with a 1973 Triumph Trophy Trail. Seems like it was
found in a barn in Idaho, I believe. It is one of the "core" bikes that I am always talking about; mostly all there but will require a total rebuild of the motor and chassis. I have not been much of a BSA single fan, even though I have been using a B44 for our dual sport rides for the past couple of years. There is something negative to me of a noisy valved, clunky feeling , slow revving British single. If you ever saw it you would believe it to be unique. It consisted of a street B44 model with blue fiberglass tank, adapted to dual sport using forks off of a 1981 Yamaha IT465, modern Acerbis fenders and
number plate light, and other neat modern features like Answer Pro-Taper handle bars, Works Connection perches, Gunnar Gasser throttle, Progressive Suspension rear shocks, CZ front wheel, and a custom seat. You see, I can not leave a bike alone when I know that better adaptable parts are available. Performance and comfort beat originality in my book. Well, the new project Trophy Trail will not escape my modification hand. The plan is a rebuild of the motor, use of the stock seat and tank, and replacement of the inadequate front forks with ones from a1980 Yamaha YZ465 with the Yamaha front wheel. Of course, I'll have Pro-Tapers, Gunner Gasser Throttle, Progressive Suspension rear dampers and springs, and Works Connection controls.

The Plan:

The Trophy Trail was pretty rough when I got it from Barry. It was mostly there and what was not on the bike was in boxes. The motor appeared to never have been totally apart. It came with extra wheels and fork legs. Unlike my BSA projects the frame was going to need minor welding repairs and paint. Our gracious editor, Joe III, gave me a brand new seat and a nice gas tank that was in much better shape than mine. For forks I went searching for an old Japanese bike. My son found the 1980 Yamaha YZ465 at one of his customer's businesses. The price was right and the forks appeared to be in excellent condition as did the front hub. The bonus was that the front brake was double leading edge. I was able to sell the rest of the YZ ending up with the forks and the front hub for a nice price.

The bike would need the engine rebuilt: new pistons and bore job, a valve job, all seals and gaskets replaced, the crankshaft sludge trap cleaned (must split the cases), new rod bearings, and replacement of any parts that looked too well used or broken. As the transmission of these 500cc Triumphs is the weak point, the transmission would be thoroughly inspected. The two that I have done so far have require repairs in the trans.

The chassis would require: welding repairs in the area near the side stand, a new side stand fitted (found an after market one in my junk pile that was more robust than the Triumph original, which was missing), the YZ forks fitted, the new plastic rear fenders fitted, and tons of extra doodads removed (like the chrome rear fender brace). And of course the frame and chassis parts would need paint-powder coating preferred.

The Yamaha forks would have their triple clamps modified to allow fitting to the Triumph frame while the fork tube's travel will be limited to 8 1/2 inches from 12 inches. There is no surer way to turn a old British bike into a handling monster than to try to give them 10 to 12 inches of fork travel. The original Brit geometry, not easily modified, is all wrong for long travel. I have found that 8 1/2 inches fork travel works fine if rear wheel travel is about 4 to 5 inches with one inch longer rear shock overall length.

The wheels would need to be torn down, the hubs and brake backing plates polished or repainted, and new Excel rims spoked up with new stainless spokes. The tires would be DOT approved knobbies: 4.00-18 rear and 3.00-21 front.

The electrical system would use the original alternator (standard battery ignition 12 volt stator and rotor), a Boyer battery eliminator Power Box, the headlight that is part of the new UFO number plate/headlight assembly, a small off road tail/stop light assembly, a heavy duty lighting switch, and an automotive brake light switch. The ignition will require a key switch, a Boyer analog electronic ignition module, and two new 6 volt coils (as per Boyer requirements).

With the new seat and a tank in very good condition I would not need to spend any money on those items. The tank is used and not perfect but for off road riding it doesn't much matter as one fall would change a perfect tank into a less perfect dented one. So why waist money for a perfect tank?

So much for the plan. As the bike progresses the plan may have to change.

Trial Fitment:

Several issue are at hand with the plan for the chassis: steering head bearings, fork stops (to keep the turning circle manageable without the forks hitting the tank), rear fender mounting (incorporating sub fender with rear plastic fender), missing side stand, cracks in side stand boss on the frame, and removal ofun-necessary welded on brackets.

The Yamaha lower triple clamp was modified, as was the Triumph stem to
allow the forks to fit using the Triumph tapered roller bearings. A hat/sleeve was pressed into the Yamaha lower triple clamp to accept the lathe modified Triumph stem while the Yamaha upper triple tree was modified to accept the Triumph cap nut. The frame's fork stops needed only minor grinding to allow them to work adequately. Since the Yamaha forks were designed for the fork tubes to protrude above the upper triple clamp, the height of the front of the bike will be able to be adjusted as necessary.

The original fender was shortened to about 16 inches from the bottom up. This allowed two bolts for mounting. The upper of those mounts (just behind air cleaner) is shared by the front of the plastic fender. The rear of the plastic fender is mounted by the provided tabs on the frame rear loop. Later I found that in order to clear the new exhaust system several inches of sub fender would have to be removed from the fender's bottom edge. More on the exhaust system later.

The frame cracks on the side stand tab were welded up and a new retracting spring post installed to accommodate the "junk" side stand. The stand was shortened (originally long for a modern bike) to work correctly with the new ride height.

The motor was removed and the chassis completely stripped of parts for the next phase.

Frame Painting:

With the oil carried in the frame, powder coating can be a problem. The powder coating process requires bare metal which they normally get by glass beading the frame. If any beads end up in the "tank" they eventually get into the engine and wear it out, since glass beads are very hard and not ingested well by any motor bearings or the pistons. It is so important to get to really clean metal that chemical stripping is usually not considered to be adequate. Powder coating requires clean metal for correct adhesion. How do you assure NO (!) beads get into the tank? I made aluminum plugs on my lathe for the filler and the bottom of the down tube and tightly installed them.
The push on oil line tubes on the frame were threaded internally (1/4-20) and bolts threaded into them very tightly. I left instructions with the powder coater to never remove the plugs under any circumstance and re-iterated that any glass beads in the tank would destroy my engine. I dropped the frame off and waited the required four weeks. I left the side covers, foot pegs, brake pedal, brake stay, head steady, and engine plates for powder coating as well. The frame and the extra parts came back from Daytek, the after market Harley frame manufacturer and powder coating company here in Hesperia, nearly perfect. But the price to do it was about twice what I expected. Off road bikes are hard on the frame paint and powder coating, if done correctly and not too thick, is the most durable choice. I justify the cost by rationalizing that I only have to do it once not multiple times as with regular paint (it works for me). Plus it looks great!

As an aside, powder coating is done to bare metal that is static electrically charged so that the sprayed powdery plastic particles, oppositely charged, are attracted to every nook and crany of the surface. It is then cooked in an oven where the plastic powder melts and then hardeneds. It results in a plastic encapsulated product with virtually zero impact to the environment.

Engine Tear down:

The top end looked pretty good with a standard piston. But inspection by Keith Moore (Moore's Cycle Center) revealed that Triumph had installed undersized valves originally and cut funny shaped valve seats. So new correct valves and springs were installed. The crankshaft was standard and in excellent condition but the sludge trap was nearly impossible to get out. They must have LokTite'd the plug in at the factory and I had to drill it out for a 1/2 inch easy out to get it out. I have made a special tool that I put on a slide hammer to remove the tube from its' cavity. It is a good thing I took the effort as the trap was nearly completely full. The primary chain, clutch, hubs, alternator and other primary stuff was in excellent shape.

The transmission had been "repaired" previously, unfortunately. To avoid replacing a broken kick starter spring, the idiot reformed the broken end. When he couldn't get it to hook up to the retaining posts and tangs, he rotated the kick starter out of position. That keep the ratcheting mechanism from disengaging and damaged the starter gear. He then correctly indexed the starter but stuffed in an extra washer to keep the spring on it's tabs. This little mod forced the starter shaft too far to the left making the bearing drag on a step on the shaft, screwing up the step. After much thinking about how the design was suppose to work I cleaned up the damage with files and trial assembled it to assure myself that all would be OK. In this idiot's frustration
he used half a can of Permatex to seal the cover. About 1/10 that quantity of Permatex sealed all right while the rest ran into the shifting selector, hardened and made shift plate motion extremely hard. The fingers that move the plate then proceeded to override their slots, rounding the bearing edges and digging into the running surfaces of those fingers. This Permatex bath made removing the push fit selector plate spindle a slide hammer removal process destroying the spindle in the process. And of course, no selector plates have been available for several years. So a trip to the welder and an hour or so on the milling machine and some more time with a file and the
plate is like new. WHEW! The rest of the trans showed normal wear patterns and nothing else would require replacement, except for the shift plate detent spring. (This is a good idea whether it looks bad or not as total removal of the primary and trans is required to change it later).

In general the motor shows little actual wear. The speedo says less than 10,000 miles and the motor shows that level of wear. I may have won on this motor after fixing the transmission. I decided to rebore and use a new piston as a new piston in an old bore is a waste of money. The piston/bore does not get the full normal life as the bore already started out too big through previous wear. The engine pieces went to Keith Moore (Moore's Cycle) for the new bore and the valve job. Next was waiting for the work to be done and for all the engine gaskets, seals, and hard parts to be gathered by Keith.

Front Forks Overhaul and Modification:

The Yamaha front forks, having already been trial fitted, needed new seals and to be shortened. This required the fork legs to be disassembled. All internal parts were thoroughly cleaned, inspected, and the seals replaced. The fork bushing were found to be un-worn and could be reused. The shortening process involves installing a spacer under the anti-topping spring on the dampener rod. This spacer keeps the fork legs from fully extending, thereby limiting the available travel. The spacer was 2 5/8 inches long to reduce the travel from 11 1/8 inches to 8 1/2 inches. It was machined from aluminum, kind of like a tube with the internal and external diameters sized to match the anti-topping spring's internal and external diameters. The preload spacer on the top of the main springs was discarded and the main
springs shortened to be just below of the top of the stanchion withnthe legs extended to their new length. This was about two coils of the spring since the original discarded preload spacer was about 2 inches long.

Wheels:

Why build a bike with loose wheel bearings, crummy looking hubs and rusty or corroded rims? I don't! So the wheels were measured up for offset. I then marked for the "master" spokes on each set of four master spokes, the old rims, and the hubs. The old rims were also marked as to which side was the brake side. All this marking assures that when the new rims and spokes are built up no mistakes are made in assembling the parts. A photo of each side was also taken to assure my old memory didn't screw up the wheel assembly. All the rest of the spokes, except for the masters, were cut off with a die grinder and the wheels disassembled. If you are doing a non-standard wheel you can take the old rim and the four master spokes to your rim and spoke provider so that he may match them perfectly. Every combination of hub and wheel size requires a different drilling of the rim and specific set of spoke lengths and end bends. Each hub was cleaned and polished, if necessary, after the old bearings were removed. I use my bead blaster for most aluminum cleaning but be aware that the tiny glass beads will hide in all the nooks and crannies of any part, only to come out when the bike is running. Glass beads are harder than any metal and will destroy a running engine. Be careful what you glass bead! Each hub was then washed in hot water and Simple Green. The new bearings, doubled sealed bearings from a bearing house rather than a dealer (much better pricing and the double seal option), were then carefully installed. The assembly/truing, using new Excel rims and Buchanan stainless spokes and nipples, went without incident. I chose the flangeless WM-1 x 21 for the front and the flangeless WM-3 x 18
for the rear. See my previously published article on lacing for more wheel assembly information. Actually Buchanan's gave me the wrong spokes for the front wheel at first: lengths for a 19 inch rim. The trick is to take the old rim and the four marked master spokes and compare them all to what ever they give you. I took them but "trusted" that they got it right, which they didn't.

For tires I selected a Dunlop DOT 21 inch knobby and for the rear a Kenda Trackmaster II DOT 18 inch knobby. Knobbies for a dual sport bike are the best choice as dirt traction is more important than street traction. You just have to cool it when on the street, keeping from heavy lean angles on curves and slowing down a bit for safety. A compromise might be "trials" type tires but they are nearly impossible to find. Knobbies work very well, thank you.

Chassis assembly:

The sequence of chassis assembly is important to minimize the installing and removal and re-installing of components in order to install other components. The sequence I used was: frame, swinging arm, forks with empty handlebars, front wheel, both fenders, rear wheel, side stand, rear shocks (Progressive Suspension units from CR Racing in Fallbrook), partially assembled motor (more on that later), oil lines, finish motor assembly, carb and air box or filter, controls on bars including switches, control cables (custom made TerryCable products made here in Hesperia), electrical wiring, side covers, seat and tank (which are prefitted even before assembly starts) and gas
lines. After installation of the side stand you now have a roller. This allows assembly to be done over time without taking up your work area forever. In my case it allows me to work on other bikes (race bikes for vintage motocross) using my motorcycle lift with the partially completed Trophy Trail rolled into a corner.

I installed the crankshaft, the cams and timing gears with their cover, and the transmission into the cases on the bench. The trans was checked for gear selection capability on the bench. I then installed that motor sub assembly into the frame at the correct time. What this does is minimize the weight of the motor during installation making handling it a one man job and reducing the possibility of damaging the paint on the frame tubes around the engine. After the motor sub assembly was in the frame I add the pistons, the barrel, the head and rocker boxes and finally the primary stuff with its' cover. The clutch was adjusted while the outer cover was off and the valves were
adjusted for correct clearances. Intake manifolds and head steadies were added last. This approach works on most engines but some engine/frame combinations can only be done this way due to minimal clearances in the engine bay. The Trophy Trail frame is a modified BSA B50 frame and the large main tube that acts as an oil tank demands that only the 1973-74 Trophy Trail 500cc Triumph motor can be used. Earlier engines must use the Trophy Trail head to be installed in this fashion which can create interchangeability problems as early heads combustion chambers are different using different shaped piston tops. The head bolts are a combination of studs and extremely deep special head nuts. The standard T100 head bolts cannot be withdrawn or installed because the central tube is too wide. The spaces are so tight I am not sure that any motor can be removed or installed fully assembled. My way with the stock motor is the easiest way I know to do it.

Electrical:

I have chosen to use a "battery ignition" batteryless with a Boyer analog electronic ignition module. To get to batteryless you throw away the battery, the rectifier, the zener, the large Lucas capacitor and replace it with a Boyer Power Box. The Boyer electronic ignition gets rid of the points, condensers, and the mechanical advance mechanism. I decided to try a double ended coil (one coil serves two plugs) that I got from Keith Moore. The spaces are tight on a Trophy Trail and I was able to mount the coils and the two modules on a triangular shaped plate under the right side cover where the battery box used to be. I separated the lighting circuits from the ignition
circuits and set it up so that no lights come on until you select the high or low beam head lamp. That assures I'll be able to start the bike without the battery then switch on any of the lights. All the lighting and lighting control was done on the backside of the number plate/headlight assembly. It was fed from the Boyer Power Box positive lead and a ground wire from the common point ground terminal mounted to the triangular electrical systems plate (remember, where the battery box used to be). A single wire returned switched 12 volts back to the brake light switch and tail light when the lights are on . For a source of AC power the alternator's wires were twisted then routed to the Power Box input wires. The coil positive terminal was used as a
distribution point for all +12 volt DC while the coils negative terminal was connected to the appropriate wire from the Boyer Power Box. Note that this bike was wired negative ground because not even the Brits wire things positive ground anymore. The common point ground stud had wires from the tail light assembly, the two electronicmodules, and the headlight assembly. The frame was not relied upon as a return path, but the stud was hard tied to the frame so that the ignition could use both the motor and the frame as a ground path. Good grounds are very important. Very importantly the trigger wires from the magnet/trigger coils assembly in the points cavity were twisted then routed away from all other wiring. Any "noise" induced into those two wires can produce false triggering of the ignition with very bad
results.

In the former points cavity I had installed the magnetic rotor and the magnetic pickup coils as per the Boyer instruction with one modification. I have found that the taper on the Boyer magnetic rotor is rather crude and can slip inside the taper in the cam. There is no key and tapers rely on friction to engage. With rough machining on the Boyer rotor there is less than adequate friction to keep it from slipping (don't ask me how I know). I install a spring lock washer on the hold down Allen bolt followed by a thick washer, then I LocTite the bolt threads (blue LocTite).

Details:

The exhaust system was done by my friend Mark Mc Dade in stainless tubing. The muffler was custom made with an aluminum outer tube, stainless 'glass pack" internals and a flat plate on the back to take a SuperTrap spark arrestor plates (12 to 18, dependent on desired noise level). The header pipes were styled after the old accessory MCM system, 2 into 1 under the engine with a collector pipe that jumps over the swing arm pivot and out the side. The original system was 2 into one at the front of the engine, weighed a ton with its' "box" muffler under the engine, and was constrictive (my original supplied muffler was also sans spark arrestor module).

The carb was a new exact replacement Amal Concentric, again from Keith
Moore. A clamp on foam air filter was used with the special adapter ring on the carb mouth (see Keith Moore). During the assembly process I decided to have my original tank de-dented and polished and to apply small triumph stickers to the sides. It looks more racy that way.

The seat was another gift item from our Joe Powers: a new reproduction
unit, that didn't have a much cracked base like my original.

Finish:

After adding the chain, the original speedometer with a new "modified to work" cable, oil, and finally gas I was ready to start it. I first removed the pressure switch on the front of the motor and temporarily fit a hose connected to a pressure gauge. This assures that I know the motor has oil pressure when I first start it. After initial starting I replace the gauge setup with a pipe plug as pressure switches can and do leak. After the engine had been running a few seconds the oil pressure came right up to about 60 psi and oil started returning to the oil tank (I observed it by removing the
tank's oil cap. The engine started on the second kick and ran smoothly. A small adjustment to the air screw and the idle speed got a nice smooth idle. The ride up and down the street in front of my house showed that the gear changes were smooth (unlike my 500cc twin Triumph powered Rickman). The shift plate and the new detent spring are working well (On the Rickman I did not replace the detent spring, shame on me!).

Conclusion:

So far the only thing that will have to be revisited is the final gearing.
The initial ride showed that the motor was reving pretty high just to be running along at even 50 MPH. The stock TR5T gearing was 18/53 while the stock gearing on a T100C was 18/46. I found a 47 rear sprocket at Keith Moore's shop and went with that. I have since riden a fast loop off road. The new 18/47 gearing is great but the seat height is too low for my 6 foot 2 inch frame. I will take the bike over to my favorite seat guy, Rip and Tear, and have him make the seat flat, front to back, and at the height of the current rear kicked up end and even with the top of the gas tank. The bike needs to
be in the right gear unlike my BSA single which would pull from real low down, just slowly. The Triumph will bog if in too high of a gear; typical Triumph 500 performance. It will break the rear end loose at the touch of the throttle. The suspension seems to work well, even better than my BSA. All in all, I like the new bike much better than my BSA single, but I always did
like twins!

I hope you enjoyed reading about my latest project. As always, the fun
of these old bikes is in building them. This one is like new from the bottom up, new rims and spokes, and with comfort mods like ProTaper style bars, a new seat, a longer travel forks. After having done this multiple times it was a lot easier this time. I have found all my sources of parts and services, which makes things go a lot easier. Why don't you go for one of these project too.