[GrandPaulZ]

Sort out the title before you start spending.

THIS!!!

 

[KADUTZ]

Diode? Not in the headlamp area. If you mean the Zener Diode then it was mounted in a finned heatsink under the headlight and easily accessible and visible till around 1976/7 [somebody will correct me on this], after this it was mounted on the alloy for the air intake box, a single unit till around 1980's then a 3 pack after this.
Yours will be mounted on the airbox alloy.

I believe there was a requirement passed in the US that required motorcycle headlights on with the ignition on effective vechile build date 1/01/78. By coincidence that was the same date for increased emission requirements for vehicles built on or after 1/01/78. In the US the T140V and TR7 models were no longer in compliance. Therefore the T140E (E=emissions) was developed with the new head, MKII carbs, revised crankcase ventilation etc.

The EPA approval for this model was, only received in December 1977. Once the approval was received Triumph needed to acquire the necessary parts to assemble the new model. Without the T140E no new machines built after 01/01/78 could be sold in the States. The first T140E was BX04570 this also would have been the first machine fitted with the lights on diode assembly and a different lighting switch.

This part would have only been on 1978 Model Year T140E model. It is shown in the 1978 T140E parts book supplement #TMA-9. Should you be interested it's on many online sites. An example is at www.classicbike.biz it is shown at the end of the 1978 parts book. Unfortunately I have never seen a wiring diagram showing the assembly installed. I assume getting the updated wiring diagram into the owner and workshop manuals was an oversight. All 1978 models used the same wiring harness.

I hope this clarifies the diode question.

K

 

[GrandPaulZ]

Dang. My oldest (2005) Excel spreadsheet in my backups doesn't show my '78 Bonnie 750, or I'd be able to see the serial number from it... The older ones are on ZIP 100MB floppies and I no longer have a working drive...

 

[Missouri Bob]

@KADUTZ : The wiring is a bit of a mess. Fortunately, it appears to be relatively simple. I need to sort through the harness to see what is missing before I can test the EI module. I would much prefer points and condensers.

 

[KADUTZ]

Something else to look for at swap meets....

K

 

[StuartMac]

Hi Bob,

The wiring is a bit of a mess. Fortunately, it appears to be relatively simple. I need to sort through the harness to see what is missing before I can test the EI module.

Your starting point for comparison should be the Triumph '73-'78 750 twin Workshop Manual wiring diagram on .pdf page 191.

Reason I say "starting point" is that's actually the ('76-)'78 T140V and TR7RV diagram; as posted earlier, there isn't an original '78 T140E diagram. Nevertheless, the ignition circuit wiring should be (was originally) exactly the same on your bike ... post if you want be to detail the ignition circuit in the diagram.

... 'til you get to the White/Yellow ("WY") wire from the "ENGINE STOP" to the coils' negative terminals ... if your bike has an EI, White/Yellow won't (shouldn't) be connected to either of the coils, rather it should be connected to the EI module input wire. If you post a photo of the actual EI module on the bike, I can advise what EI wires should be connected where.

Be sure this has nothing whatsoever to do with the lighting wiring or speculation about what PO might or might not have changed.

would much prefer points and condensers.

Ime, you wouldn't - Britbike owners have been converting to EI for decades, many spares generally aren't great quality anyway, when suppliers are supplying into a shrinking market, they're even less likely to make an effort over quality; EI's fit-and-forget and all have a better advance curve than the best original Lucas auto-advance units ever had.

You have a private "Conversation" too.

Hth.

Regards,

 

[Missouri Bob]

Boyer Bransden ignition module. The WY wire from the harness connects to the EI's W wire. It appears that the EI's R wire is grounded, and its B wire provides power to the coils (in series). BY from module to BY in harness. BW from module to BW in harness.

The zener diode and the rectifier are wired correctly. Adjacent to each coil is a small cylindrical component resembling a condenser. One has WY wires connected to it. The other has nothing connected. Would there still be a condenser without breaker points?

 

[StuartMac]

Hi Bob,

Boyer Bransden ignition module. The WY wire from the harness connects to the EI's W wire.
its B wire provides power to the coils (in series).

As the coils are in series, they should be '6V'; however, some owners just connect the original '12V' coils in series, because Bransden (the actual maker of "Boyers") said they could. In reality, two '12V' coils connected in series is mostly less reliable ime.

If the coils are 'original Lucas', they'll lave either "17M6" or "17M12" stamped on the ends opposite the terminals. If you want to check, first wiggle 'em side-to-side in the rubber rings to break the stiction then I smear cheap spray-on furniture polish on 'em to lubricate 'em through the rings.

appears that the EI's R wire is grounded

This might work. However, as you probably know, as the ignition circuits (through the module and coils) are from battery -ve to battery +ve; the harness has a network of 'ground' (Red) wires and insulated connections to battery +ve, using random bits of bike and uninsulated connections to them is crazy, not long-term reliable ime.

I connect the module Red wire directly to the battery +ve terminal, the coil series +ve either to harness Red wires or directly to the battery +ve terminal.

BY from module to BY in harness. BW from module to BW in harness.

BY and BW in the harness originally connected the coils' +ve terminals to the points and condensers, so most EI makers use them to connect the EI module to the trigger unit in the original points/AAU cavity in the engine timing cover. Generally reliable but, if the harness looks past its best, look hard at the BY and BW wires in the harness and the connections at each end, consider replacement, the signals from the trigger unit are low Volts and Amps, they need the best connections possible.

At some point in the future, I advise adding a low-Amps fuse to the ignition circuit; reason is Bransden advises current through the EI module shouldn't ever exceed 5A, the original fuse near battery -ve is 17.5A continuous ... Fwiw, I fit a 5A automotive blade fuse and holder where the WY connects to the EI module W wire.

View attachment 831208
Adjacent to each coil is a small cylindrical component resembling a condenser. One has WY wires connected to it. The other has nothing connected. Would there still be a condenser without breaker points?

In your photo., if you mean the small cylindrical component with a male spade terminal, beside the coil spade terminal with the Black wire on the upper coil, that's a condenser, the lower coil should have one beside it too.

EI, condensers should not be connected to anything.

Points, there was originally a WY wire connected to each coil's -ve terminal. Only one WY terminal was required to connect to the EI module White wire; failing a direct instruction, the EI 'fitter' obviously thought the other WY should be connected to something ...

Standard harness, fwiw I usually leave the unused WY spade terminal, just tape it up securely. Reason is, if you have to troubleshoot the ignition circuit, it's useful to have a 'hot' terminal that can be connected to the coils series bypassing the EI module.

zener diode and the rectifier are wired correctly.

Long-term, if you decide to keep rectifier and Zener, while they're generally reliable, be aware particularly the Zener has a poor 'ground' path - from the airbox to the battery carrier then though an edge to a washer with a bunch of Red wires soldered to it. Consider drilling another small (3/16" ID) hole beside the Zener, bolting a ring terminal with a Red wire there, connecting the Red wire to existing harness Red wires.

Aside, up to '71, Lucas gradually evolved motorcycle wiring to be pretty reliable. Then, for some reason, just the new OIF harness implementation regressed several years in evolved reliability, the contemporary 'dry frame' harnesses continued to be better.

Hth.

Regards,

 

[Missouri Bob]

@StuartMac : Thanks. That's exactly the information I needed.

 

[Missouri Bob]

If the coils are 'original Lucas', they'll lave either "17M6" or "17M12" stamped on the ends opposite the terminals.

They're "17M6", which I assume means 6 volt coils.

 

[StuartMac]

Hi Bob,

They're "17M6", which I assume means 6 volt coils.

Regards,

 

[DU75xxx]

Have you run the VIN number yet? That should tell you something. Try vehiclehistory.gov.

Nice tip! Will any of those sites look up older Triumph SNs?

 

[DU75xxx]

Nice tip!

Will any of those sites look up older Triumph SNs?

 

[DU75xxx]

Nice tip! Will any of those sites look up older Triumph SNs?

Seems like the answer is NO.

 

[maxkim1951]

My buddy, Charles, called me yesterday morning to ask if I was interested in "an old Triumph motorcycle". He didn't have to ask twice.

A friend of his knows an older woman who is moving out of her house and wants to get rid of everything, including the Triumph that had been owned by her late son.

Fortunately, it has been parked in a garage/shed/barn for the past thirty years. That's probably why the motor isn't seized with rust. No title and no keys. It's missing a few parts, but with perseverance, I'll be able to find replacements.

It's a T140E. I'm happy that the shift lever is on the left side; don't know how well I could adapt at this point in my life.

View attachment 830967 View attachment 830968 View attachment 830969 View attachment 830970

The first order of business is that of getting the motor running. If that proves to be satisfactory, I'll begin the process of getting a title. Colorado makes that somewhat easier for vehicles at least 25 years old.

The tank was repainted an unflattering shade of white. I expect to find bondo under the paint.

This will be a lengthy project.

Plan on a lot of new parts for the brakes. A vintage Brit bike will have issues with the "sludge trap" in the crankshaft possibly being jammed full of crud. Once you start sending warm oil through the system, it's not uncommon to have it seize the rods to the crank, and if that happens at speed, you can end the project right there with a hole in the crankcase, a broken rod, and the cylinder skirt blasted off. So, you might want to plan for a complete engine strip-down, too.

 

[maxkim1951]

Hi Bob,




After thirty-odd years unused, it's unlikely there's any oil between parts that absolutely need oil between them when spinning at several thousand rpm; before attempting to start the engine, please read Waking The Sleeping Beast.

Only thing to do differently is put a little less oil in the crankcase than WTSB recommends - it was written for triple owners, and triples have larger crankcases; twin in the US, maybe a pint to pint-and-a-half; risking stating the obvious, subtract whatever quantity you put in the engine from the total engine oil quantity recommended for a T140E.

Luck.

Regards,

It's likely that almost all of the oil in already in the case, so drain the oil from the case, the tank/frame, and the gearbox. Refill and prime the case with a cup of oil or so fed in through the rocker box access covers, squirt it all over the rockers and springs, it will drain down to the case through the holes in the tappet blocks.

 

[maxkim1951]

I just checked compression. I think that someone put oil into the cylinders when it was parked; both plugs were loose. 100 psi in each cylinder. I expect that those numbers will improve after I go through the valves and seats.

It would likely come up just by running for a while. But starting this with a crankshaft full of grit and goo is a risky, risky operation.

 

[StuartMac]

Hi,

prime the case with a cup of oil or so

Uh-uh; as you quoted:-

read Waking The Sleeping Beast.

Only thing to do differently is put a little less oil in the crankcase than WTSB recommends - it was written for triple owners, and triples have larger crankcases; twin in the US, maybe a pint to pint-and-a-half;

... a "cup of oil or so" is not a high-enough level in the crankcase to be picked up by the spinning crankshaft to splash-lubricate the bearings that need it.

A vintage Brit bike will have issues with the "sludge trap" in the crankshaft possibly being jammed full of crud.

A high-mileage vintage Brit bike might have issues with the "sludge trap" in the crankshaft possibly being jammed full of crud ... a low-mileage engine shouldn't have problems as the sludge trap doesn't fill up rapidly in early mileage.

Unless I've missed it, @Missouri Bob hasn't posted the bike's mileage?

Once you start sending warm oil through the system, it's not uncommon to have it seize the rods to the crank

The position of the sludge trap in the crank says it's a centrifugal filter. Unless the trap is very full, "warm oil through" it says the crank is spinning, keeps any trapped debris in the trap, filters any new debris.

Hth.

Regards,

 

[StuartMac]

Hi Bob,

The first order of business is that of getting the motor running.

In addition to reading Waking the Sleeping Beast, I'm guessing you'll remove the "Sump plate" at the bottom of the vertical part of the frame spine tube?

You should find a gauze filter attached to the plate. You can substitute a proper micropore filter element for the gauze.

Proper micropore element on the plate is colloquially known as a "Charlie's filter" after the Bristol Triumph dealer (Charlie's of Bristol) who apparently first fitted the filter element BSA fitted as standard '71-on to their singles, to the OIF Sump plate. The element is available under the original 19-4590 part number, or a couple of aftermarket parts makers offer a complete replacement Sump plate with a filter element attached, e.g. Motao. As with many aftermarket parts, there are a few gotchas to be aware of; users'll likely be along to post chapter-'n'-verse.

Hth.

Regards,

 

[Missouri Bob]

Unless I've missed it, @Missouri Bob hasn't posted the bike's mileage?

The odometer shows just under 7,000 miles. Although I would like to believe that is accurate, neither tire (tyre) looks to be original.