October 2019
This bike looks remarkably good considering its age and having a reasonable mileage. Interesting to me that it was NZ new but has MPH speedo, US tank but possibly home market bars. Things were getting a little ragged at the Triumph despatch dept in those days.
Always an amazing riders-eye view of these fuel tanks.
The bike had come for the addressing of some tuning problems, which sounded to be an over rich situation just off the idle stop, as in riding in town. This has become an increasing problem with many bikes coming my way. It may be the changing nature of modern fuel, but I suspect it is being exascerbated by lack of quality control on some new parts - needles and needle jets in particular. However, that is just based on my experience with previous bikes. Let us see what it might be with this one.
Carbs were removed from the bike and stripped. First thing I noticed was something that stumped me for a long time with another T140E and its Amal Mk2 carbs. One of the spray tubes was beginning to diminish.
Spray tubes are small brass sleeves which protrude up from the floor of the carb throat around the needle, and they provide a small reservoir of fuel to supply the shortfall when the throttle is suddenly snapped open, rather like an accelerator pump would. The loss of this feature makes the engine run very lean, and if not detected, causes owners to adjust the mixture in a richer direction to attempt a cure, which then leads to other problems - such as being experienced here.
The spray tubes are inserted through the main jet holder opening and swaged in place, but this process seems to be a bit hit and miss considering I have found the same problem on several sets of Mk2 carbs now. The other one had allowed the spray tube to vanish completely. Fortunately the solution is very simple and just involves driving the tube back in place and adding enough impact force to allow the lower flared edge of the tube to engage with the inside bore of the jet holder opening and remain in place in future. This was done.
There was some apparent discrepency in the heights of the two throttle slides, which indicated that a previous tuner had made allowances for the problem without identifying what it was. The pilot air screws were also at odds, with one being 1½ turns out and the other 3½ turns out, while they should both be 2½. There were also a few adjustment problems with the throttle cables discovered as it all went back together after treatment, so hopefully we will be able to achieve a much happier state of tune when it is all back together.
Besides checking every jet, float heights, slides and needles, the choke mechanisms came in for close scrutiny as they can leak fuel into the idle circuit if they do not shut off properly and that can create a rich situation. Apart from some straightening of the levers, and reshaping of the friction mechanisms that keep the choke on, no parts were found to need replacing and were all restored to service. The needles and jets were found to be the leaner versions of two possible variations, so it made sense to retain them as they were. Throttle behaviour at higher settings was absolutely fine in use, and it was only the low end behaviour that was a problem.
Carbs were reassembled and refitted with all settings restored to standard as a suitable starting point for tuning.
Another reported problem with the bike was to do with the ignition switch, which had a few false positions and a dead spot between ignition and igniton plus headlight. I noticed that the key was inserted upside down, so removed the idiot light binnacle and investigated. Sure enough the switch had been fitted upside down and the wires were now on the wrong terminals, so that was all put to rights and the missing cover fitted. Electrics now behaved as they should.
While attending to the binnacle it was obvious that the speedo and tacho cables were forcing the clocks out of their rubber holders, due to a bit of excess cable length. I chose to apply a bit of silicone sealant to locate the gauges to the housings so they would not move in future. Nothing more annoying than clocks that rotate themselves while riding. This is why they are absent in the cover picture for this bike.
Fuel tank and all the other bits now got refitted and the whole thing was left to ferment overnight.
A bit of late afternoon sun today saw the bike outdoors and a trial start. Lit up easily and I warmed it for a minute before tuning the idle and synching the carbs.
That complete we were off around the blocks to see what happened. It ran nicely and apart from the first half a mile of warming up it could not be caught out from any throttle position, so the state of tune is pretty damn close. Air temp - or lack of it - was not enough to get the engine really hot, so some fine tuning may be necessary on such a day, but for now I think it is good enough to do some miles and see how it goes.
Currently seem to have a blue/silver theme going on...
Both bikes are heading back to their respective owners in a happier state. I guess that is the game.
Close of play 23 October 2019.