Opinions on the 70s 750 triumphs.

stay away from 71/72, they had higher frames and trans problems,
the 1973 and 1974 are my favorites.
they had right side shift, disk front brake, drum rear, the Amal mark 1 carbs, and regular old points ignition.
after 1976 they started getting weird. left side shift and problems with the linkage, Lucas E/I ignition, Mark 2 carbs, poorly designed rear disk brake, neutral switch, mag wheels. even electric start.

Some of the later T140's had a detuned camshafts which can replaced with hottter cams. I run a 1976 T140 in my Triton and converted it back to right hand shift, balanced the crankshaft, modern bearings, ported the head and she flies.

My '73 Tiger with electronic ignition is undoubtedly the best running, most reliable of any pre-Hinckley Triumph I've ever been around. I say '73 and '74, get the single carb head and you're riding the best Triumph option out there. Others have figured this out, though, and they are getting harder and harder to find.

Forgot to mention that they are FAST, too.

My '78 is the best bike I've ever had:

Triple brake calipers (like Slippery sam the Trident racer)
Balanced Crank
Gas flowed head
Hot"ish" cams
Box section swing arm
Improved lubrication & cooling
Billet con rods

You can do so much to these bikes to make them brilliant. Almost all parts are available as new old stock, and there are many good re-pop parts available as well. Look good with hard tails as well.

I race the dog snot our a '76 T140 in AHRMA.

Love it!

By the time Triumph had developed the T140 they had pretty much refined the Bonneville twin to its zenith. Gutsy, smooth and fast...personally I would stick with the pre '79 models, just because I like the old Amal concentrics better.