Reading other internet forums about Meriden Triumphs, I'm really surprised at the poor information so far in this thread.
Unless you have some sort of medical problem with your left hand, those gadgets are - at best - a solution in search of a problem; at worst, snake oil in search of a sucker.
I spent years in London either as a dispatch rider or commuting on motorcycles - apart from none of the listed Japanese manufacturers make bikes that can't be used all-day every day in London by normal human beings, Triumph sold thirty-odd thousand twins a year around the world for years, which would've been impossible if they also couldn't be used in cities like London all-day every day by normal human beings.
Having renovated the clutch and fitted new springs
That's the obvious starting point. Which springs? Where did you buy 'em?
You haven't helped yourself by failing to state which year "T140V" - Meriden made 'em for five years. However, because I can be bothered to look beyond half-arsed gadgets, I looked in '73 and '78 parts books and found the same clutch spring part number listed - 57-4644. Then, although I'm not particularly interested in T140's, even I knew there are at least two different actual springs sold under that part number, and a few minutes searching another Britbike forum turned up the details - both have the same free length but different fitted lengths, which results in one being 53 lb./in. and the other being 76 lb./in. So, as I say, where'd you buy the new springs from, and which ones have you fitted?
Aside from the springs themselves, even I know there are several other potential problem areas, mostly with current parts 'quality'.
Are the "Pressure nuts" set correctly on the bolts? Accepted wisdom is the ends of the bolts should not protrude beyond the nuts. What make of cable are you using? When it was off the bike, did you check that the inner drops through the outer under its own weight when the cable's held clear of the ground? Is the cable the longer 'US-market' length, even if your bike has 'low' handlebars? With low 'bars, route the cable around the front of the frame, the cable then keeps a desirable large-radius bend even when the steering's turned fully to the left. Did you check the handlebar lever pivot for wear-related friction, especially under strain when it's compressing the clutch springs? Does the lever measure 7/8" between the pivot centre and the cable nipple centre? That's the correct measurement for any pre-'79 Triumph twin, greater requires (a little) additional lever effort and doesn't do anything for the clutch actuation mechanism in the gearbox cover. Does the lever mounting also measure 7/8" between the pivot centre and the cable inner where the latter passes into the adjuster, when the lever's up against the mounting?
