December 2018

I got a phone call from a stranger. It seems to be a recurring theme. He took his problematic T150 to a garage for a wof, and asked if they could tune it. They said yes and gave him my phone number. He called me and some time after he brought the bike around. I loved the look of it as it reminded me of a T140D Special and I am guessing that was in the brief of the builder too.


The bike had been seriously modified in a number of fashions. Lester wheels were the obvious visual clue, but there was a rear disc which had been well engineered as far as both caliper mounting and master cylinder were concerned.


Brake pedal and master cylinder are well thought out and function as well as they look. Chrome chainguard's origins are unknown to me, but presumably worked from the owner's perspective


The twin front disc setup was exactly like my own, which suggests that Les Williams originally supplied it as a 'Legend' kit. I can vouch for how superbly it functions.


There were a number of issues with the bike, mostly to do with its horrendous state of tune which was totally carb related. It ran so rich at town speeds that the plugs would foul and cease firing. This was confirmed by both the state of the plugs and a quick run with a colourtune plug. At idle it was fine and at over half throttle likewise, so it was slide/needle jet/needle related in my view.

Stripping the carbs revealed that they had 2 slides fitted, whereas 3 would be usual. This would definitely contribute to the problem, although it appeared that somebody had previously attempted to open the cutaways slightly. The needle jets and needles were quite worn but of the correct type. The needle was at its lowest setting which indicated that this had been tried as a means to lean it a bit.

As it happened, I had another Trident with exactly the same problem at the same time, although it was a T160 which has leaner needles and slides to begin with. The symptoms were almost identical despite all the internals on that one being correct. I had tried fitting the complete carb setup from another T160 to it as a test, and it now ran perfectly. So it was the carbs, and now I had two sets.

As you have to change something to move forward or to simply eliminate what does not help, I decided to fit a new set of 3 slides to the T150 plus a new set of stock 106 needle jets. I had tried fitting 105 needle jets in the errant T160 but that had made it almost as far too lean as it was rich.

The slides and needle jets showed up. The new anodised slides are pretty expensive at $60 each, but they looked like pretty good quality and promised to wear far slower in future. The needle jets were on the other hand, rather odd. The side drillings allow a small amount of air to mix with the fuel, and are normally around 0.035", but the drillings on these new items appeared to differ from one another, to the tune that you could see it with the naked eye.


While this was disconcerting, the manufacturers state that the jets are "flow optimised", so perhaps they had used the side drillings to fine tune the performance of the jet. Only way to find out was to fit them and see what happened. So I did. What happened was that nothing changed. There was a very slight difference to the pilot screw to accommodate the leaner slides but that was it. The bike was still running as rich as a very rich thing.

I spoke with a friend who messes with carbs and he suggested that I might be able to fine tune the jets myself. Drilling the holes further would allow more air to mix with the excess fuel and thus lean it back. As I was 90% convinced that the needle jets were the problem I figured this would be the best approach, and not too expensive should I destroy the jets in the process. I posed a question on Triplesonline and one response was from someone who had done this before. He advised not to exceed 0.004" oversize, although I am not sure what might take place above that. Initially I drilled both holes out to 0.0374", reassembled the carbs and tested the bike.

Huge improvement, but I could tell that it was still too rich by the behaviour on a trailing throttle, where it kind of "gargled" fuel a bit. The whole lot came apart again and this time I drilled to 0.0393", so just over the 0.004" amount. This time the bike was so close to spot-on that I stopped right there. Starting was still great, and throttle response was very good, although it felt just a tad flat around half throttle. I imagine that the lean needle setting might now be responsible for that glitch, but it also might not, and it takes so long to strip and rebuild, tune and ride, that I decided near enough was near enough. Basically the bike was transformed as far as the original problem was concerned, and the owner was very happy with the result. He had taken the bike to several places previously, but none had managed to get it even approaching right. If they had been trying new needle jets I think I know why. I repeated this same process with the T160 and got the same result only better, as all the other settings were better to begin with, and the entire throttle range now seemed to be exactly as it should be.

I have never before removed and refitted Trident carbs so many times to get the tuning correct. Previously I just fitted the parts that were designated in the parts book and it worked. Not this time. I hope this is not a coming trend.

The owner of the T150 had brought me another set of mufflers and some other parts which I could fit, as he was intending to sell the bike and figured his loud shorty mufflers might not be as attractive to potential buyers. I was happy with that as the other mufflers looked to be a bit more tuning friendly and I had done enough of that. He also complained that the gearing seemed to be rather on the low side. I had noticed that it was extremely difficult to get the bike on the main stand, so had been running the rear wheel onto a block of wood to help. Besides having a large rear sprocket, which may have been a one-off to mate with the alloy wheels, I discovered that the rear wheel was an 18", just as on the T140D, but this one had a 4.10 x 18" TT100 on it, whereas it should have a 4.25/85 x 18" to maintain the same rolling radius as the 19" front wheel. ffectively the rear wheel was at least 1" smaller than it should be, making the gearing even lower.


The longer mufflers fitted up well, and allowed use of some rather tasty rear footpeg mounts which had obviously been a part of the major modifications done to the bike during its rebirth. I appreciate the engineering work that has gone into the whole build - must have taken an enormous amount of time and money.


The rear master cylinder is a type I am not familiar with, but looks right at home and works very well. This whole project reeks of an owner build, given the care and attention to detail involved. I think a larger rear tyre would add something more to the balance of the look.


Nice to see something other than an oil pressure gauge between the clocks. It wasn't actually running so I opened it up and replaced the battery. It deserved to be working.


I think the overall look with the lower longer mufflers is much better, and I prefer it now to how it arrived. I do not find the seat to be pleasing to my eye, and would have opted for a T140 Special seat to complete the lookalike effect. With the small fuel tank being not unlike the T140D item I think the seat may have passed muster.


So there you have it. A somewhat happier beast than a few weeks earlier. Given time I would have made a few more tweaks, but for now I am pretty happy with how it goes and how it looks.


Very pleased to have been involved with this bike. It was built in the USA and was purchased by the current owner out of Las Vegas. Good score.


May 2019


This bike changed hands and came back to me courtesy of the new owner. It was badly out of tune again despite having been quite happy when I had last seen it. I was surprised to find that a number of parts it had previously featured were now gone, and I had to replace the handlebar mounts for a second time.

I could not however tune it, as it was burning too much oil, and because I had no room at this time for stripping an engine I sent it back to the owner with the intention of doing battle with it at a later date.


A later date arrived in January 2020, so there is another page further down for battle recommenced.