T140 D (1982) Bought For Restoration.

Post a picture and we can let you know what tank you have and of course the bike is for use. We'll get it sorted between us.
A T140D should have twin Mk2 Amal Carbs.
There's a frame number stamped just below the headstock on the left side and the same number stamped on the left side of the casings just under the barrels - these numbers will give you the month and year of manufacture.
The Triumph owners club or VMCC have some copies of the original order books and should be able to tell you where they went to from the factory. You'll need to pay unless you are a member.
Lots of experience on here so fire away

 

All the best for your project!

 

Single SU's were sometimes used to replace (upgrade?) The twin carbs for both the 750 Bonnie and the Norton Commando. Easier to set up a single carb, which (as an aside), is why some say the single carb TR7 was better than the Bonnie.

 

The engine numbers relate to C - March and A - 1979. The frame number should be in the location you've cleaned but it does look like there's a lot of pitting there.
The tank is the British 'Breadbin' type. Lots of owners went for the US version smaller tank and higher handlebars. The breadbin tanks are fine -just really what version you prefer.
It's certainly has had a fair amount of work but also not a lot of love. The engine covers have allen bolts so it's been climbed into in the past.
The SU carb isn't standard, it should have a pair of MkII Amals on the parallel cyliunder head ports.

IMO this isnt a "try to get going" bike. It is a complete rebuild. Basically take the bike completely to pieces, inspect the parts as they come off, make a list of replacements required as you go, bag and label everything up - don't just throw bits into a box thinking you'll remember - you wont.

First things to get are a workshop manual and parts catalogue. A paper copy T140D workshop manual will be easily available on fleabay.
The parts catalogue are available on British Only Tech Library free to download

https://partsbooks.britishonly.com/

look for your bike 1979 750 twin and the 1979 T140D supplement. The part numbers are quoted to suppliers for replacements. There's plenty of suppliers about.

There's a few rebuild threads on here and other forums for guidance. Todd from Lowbrow Customs has a complete T120 engine rebuild series on youtube (the engines are pretty much the same)

The engine will also need to be completely rebuilt down to the sludge trap. These engines didn't really have an oil filter, they relied on the heavy gunk to be trapped in a tube that runs along the centre of the crankshaft. The centrifugal spinning forced all the nasty bits to stay in this tube before getting to the big ends. It will, from the looks of the bike, have to be cleaned out. Don't listen to anyone who says the sludge trap doesn't need to be cleaned, it does.

The engine needs to be completely dismantled to get to the sludge trap. Do not be daunted by this, the engine is easy to work on and will allow you to ensure all is well in there before you rebuild.
With a few special, fairly inexpensive, tools you will be able to carry out everything yourself, including paint, other than if the crank journals or barrel bores need engineering work.

Take your time, it's not going to be quick (allow about 20 weeks solid work to rebuild a complete T140), just enjoy the process.

And we are here if you need help, obviously we will require photos.
Come along, crack on.

 

The T140D Bonnevilles were manufactured from 1979 until 1980 when the T140E took over early in the year. Only a few hundred were produced in 1980.

The engine number confirms it's a 1979 bike (HA - July 78 to PA - Nov 79). I assume you have the V5C showing a 1982 bike with the engine and frame number?

The standard exhaust for the T140D was a two into one with the US style tank - the larger 4 gallon 'breadbin' tank on yours was an optional buy on the D in 1980.

Looks like you'll be fine with the rebuild. I enjoy these bikes and I'll watch with interest on the progress.

 

The engine number is a T140D with an early 1979 date. The T140E Bonnevilles started in 1979 until 1982. But as with anything Triumph there are exceptions and abnormalities. They've all been worked on by now and changes are pretty frequent.

Not many differences in the D and the E other than a breather from the front rocker cover and main engine breather into the airfilter rather than out to atmosphere over the back wheel. The bikes are much the same.

It may be that yours has had a replacement engine case on that side (the engine cases are stamped underneath where the long engine bolt threads through on each side of the split in the casing with a three digit number). The factory engine builder basically had a pile of casings that he matched, paired and stamped. Or there's been an engine replacement.

I've no problem with non matching machines and have had several and have built a few myself. The purists amongst us like everything to match. I've got imported Bonnys from the US that have registration numbers that confuse the insurers. DVLA try to match as close as possible when re-registring for the UK.

Later Edit: It could, just thought of it, have been stashed in a showroom/warehouse etc and sold and thenregistered a couple of years after manufacture. They were known to sit around for ages unsold due to the erm...issues at Triumph in those days.

Looks like yours may be a 'bitsa' - nothing wrong with that in my book. Enjoy.

 

Parts Books, Service Manuals and Service Bulletins are all available as pdf files online, although no one source has a complete set. It might be worth getting a copy of Oracle 3 as a starting point.

The parts books do contain some errors so it is always worth cross checking parts, I am pretty sure there was a supplement for the T140D which compliments the T140 E parts manual. Ideally try and get parts manuals with the "General and Export" supplement as these should include the different parts used on the breadbin tank models like yours.

There are some key service bulletins which deal with specific issues not covered elsewhere. For example setting crush for pushrod tubes and changes in the rocker box assembly. Service bulletins were produced by the factory, TriCor and JoMo with the TriCor ones being the most commonly available. I have spent a lot of time gathering a collection.

The service manuals are OK to a point but often short on detail and also have some errors.

There is a vast body of knowledge available on this and other forums which is worth tapping in to. There are also quite a few knowledgeable parts suppliers out there.

Many parts are still being manufactured, often under the original brand names but these are not necessarily to the same spec as original parts.

Regarding the SU carb, I personally never liked them on cars. A better option would be modern Amal Premiers or Mikunis for which there is a deep body of knowledge. You could go single carb like the Tiger 750 but that requires a single carb manifold and you would need a different (TR7) airbox or to use a pancake filter or similar. I have a single carb TR7 with an Amal Premier and it runs nicely.

A couple of mods to think about are a TriSpark ignition (brilliant), a 7 plate Aerco Clutch (ideally with an SRM pressure plate) and a spin on filter or a Charlie's filter.

 

My TR7RV has a March 1973 Engine/Frame number but was first registered in November 1973 when it was sold by Sports Motorcycles in Manchester.