1971 T100c

rcrowley

Member
Local time
Today, 01:54
Joined
Nov 18, 2019
Messages
29
Points
7
Age
36
Location
Weymouth ma
First Name
Rich
My Ride
T100C
Hello everyone. First timer on this forum. Always wanted to do a classic build. Here's the quick story. Brother in-law got the bike about 13-15 years ago in high school. Wanted to restore a classic. Quickly discovered he was not as interested in these things as he thought. Bike has been sitting in a garage ever since. I never knew it existed until recently my father in-law mentioned it to me that he just wanted it out of the garage but didn't want to sell it to just anyone he prefered to see it rebuilt. Lucky me. He just said take it and enjoy it. Only back story I have on it is that it would not start. Someone along the lines told them the engine would most likely need a rebuild. Now I've done some non invasive builds. Such as just replacing/rebuilding carbs, some transmission stuff. I'm not expert. But I'm very mechanical and can generally figure out anything. I've also got a few friends to throw questions at. So here it is. My 1971 t100c. Unfortunately the bike was in pieces. Fortunately my brother in law is OCD about being organized to everything was bagged and labeled. Except the float and bowl assembly for the carb. Completely missing. So a test start is no an option yet. I did check the engine by the kickstart. It moved. So not seized. My question is. What do you all recommend for the next time as far as inspection goes until I can get the carb. What are some common issues I these that have been sitting for so long? Is it necessary to start pulling apart the engine and inspecting everything inside? Also, I know I will probably get some backlash on this part. I really enjoy the look of these when turned into a bobber. Id never chop a classic frame. But this rear frame is bolt on. If I do decide to go the bobber road. Wats recommend as far as frame and mods? That part is a little ahead of myself l, the plan is to get it running before jumping to that part of the build anyways. Thanks ahead of time for any help and advice provided. Extremely stoked on this project.
 

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You seem pretty handy with a wrench so just the standard common sense things; change the engine and transmission oils; check the valve clearances; squirt some oil into the cylinders and rotate the engine many times with the spark plugs out; fresh gas of course after you get a complete carb; adjust the points; a new battery; I would invest in new spark plugs too.
What's the inside condition of the gas tank?
If you plan to ride this bike quite a bit, buying a new carb is a good investment. You soon forget the cost in the satisfaction in how it runs and idles.
I'm sure the tires and tubes are very old so invest in new ones.
That will keep you busy.
Others may have more to offer.

I'm not a fan of bobbers so I'll leave that to others.
 
That isn't a standard '71 T100C ...

It might be the differences are cosmetic and easily-fixable along the way. Nevertheless, it'd help others if you'd confirm the engine and frame VIN:-

. engine VIN should be stamped on a machined-flat area on the side of the left-hand (looking forwards) crankcase just under the cylinder block; also stamped on this area should be a series of tiny "Triumph" logos;

. frame VIN should be stamped on a raised flat strip on the left-hand side of the steering casting, reading towards the front downtube; again, the strip should also be stamped with tiny "Triumph" logos but, as the casting is steel, the logos might be difficult to see;

. the numeric part of a VIN should be five figures;

. prefixing the number should be a two-letter code; the second letter will be "E" if it's a '71;

. if the bike is a T100C, that will either prefix the two-letter code or follow the five-figure number;

. if the engine and frame left Meriden (the Triumph factory in England) assembled together, both complete VIN - model code, two letters (date code) and five numbers - should be the same; if they aren't the same, post most of each, perhaps without all of figures in each number?
 
That isn't a standard '71 T100C ...

It might be the differences are cosmetic and easily-fixable along the way. Nevertheless, it'd help others if you'd confirm the engine and frame VIN:-

. engine VIN should be stamped on a machined-flat area on the side of the left-hand (looking forwards) crankcase just under the cylinder block; also stamped on this area should be a series of tiny "Triumph" logos;

. frame VIN should be stamped on a raised flat strip on the left-hand side of the steering casting, reading towards the front downtube; again, the strip should also be stamped with tiny "Triumph" logos but, as the casting is steel, the logos might be difficult to see;

. the numeric part of a VIN should be five figures;

. prefixing the number should be a two-letter code; the second letter will be "E" if it's a '71;

. if the bike is a T100C, that will either prefix the two-letter code or follow the five-figure number;

. if the engine and frame left Meriden (the Triumph factory in England) assembled together, both complete VIN - model code, two letters (date code) and five numbers - should be the same; if they aren't the same, post most of each, perhaps without all of figures in each number?


Here are the numbers. They do match as well. What jumps out at you to say it's not a standard 71t00c?
 

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You seem pretty handy with a wrench so just the standard common sense things; change the engine and transmission oils; check the valve clearances; squirt some oil into the cylinders and rotate the engine many times with the spark plugs out; fresh gas of course after you get a complete carb; adjust the points; a new battery; I would invest in new spark plugs too.
What's the inside condition of the gas tank?
If you plan to ride this bike quite a bit, buying a new carb is a good investment. You soon forget the cost in the satisfaction in how it runs and idles.
I'm sure the tires and tubes are very old so invest in new ones.
That will keep you busy.
Others may have more to offer.

I'm not a fan of bobbers so I'll leave that to others.


Ya I figured a new carb was a good investment off the bat. Haven't peaked inside the gas tank yet. But I figured I'd flush anyways. Outside of the tank is in good condition.
 
That is good. Matching numbers increase the value.
 
Here are the numbers.
One of the earliest, built in September ("K") 1970.

What jumps out at you to say it's not a standard 71t00c?

So:-

1. Front fender should follow the curve of the tyre more closely; what's the tyre size moulded on the sidewalls? Btw, T100C was fitted with a fender mounting bracket (H1688) not shown or listed in the '71 500 parts book.

2. Handlebars.

3. Exhaust.

4.. Oil tank colour (and sidepanel if it's the same colour as the oil tank). Btw, that fuel tank colour in the brochure is a candy dark orange Triumph called "Olympic Flame".

5. Rear shocks. If the rear tyre is standard 4.00x18, the shocks. are also shorter than standard.

Aiui, '71 T100C was/is rare standard. Although Triumph listed the version for '72, they never made any. "C" stood for "Competition" but, by the early 1970's, 4-strokes were outclassed by lighter 2-strokes. As the decade progressed, 4-stroke off-roaders became less and less desirable, people that got 'em ripped bits off 'em to try and make 'em usable as trail bikes, where most of 'em got crashed and bashed 'til they were scrap.
 
One of the earliest, built in September ("K") 1970.



So:-

1. Front fender should follow the curve of the tyre more closely; what's the tyre size moulded on the sidewalls? Btw, T100C was fitted with a fender mounting bracket (H1688) not shown or listed in the '71 500 parts book.

2. Handlebars.

3. Exhaust.

4.. Oil tank colour (and sidepanel if it's the same colour as the oil tank). Btw, that fuel tank colour in the brochure is a candy dark orange Triumph called "Olympic Flame".

5. Rear shocks. If the rear tyre is standard 4.00x18, the shocks. are also shorter than standard.

Aiui, '71 T100C was/is rare standard. Although Triumph listed the version for '72, they never made any. "C" stood for "Competition" but, by the early 1970's, 4-strokes were outclassed by lighter 2-strokes. As the decade progressed, 4-stroke off-roaders became less and less desirable, people that got 'em ripped bits off 'em to try and make 'em usable as trail bikes, where most of 'em got crashed and bashed 'til they were scrap.
I'll get the tire info once I head out to the garage. I did notice the exhaust and bars looked different. Question. Is there any significant importance to the link between the 2 pipes? I don't see it on the stock exhaust. I assumed it was probably taken from a later year?
 
any significant importance to the link between the 2 pipes?
It allows the exhaust pressure from either cylinder to vent to atmosphere through both pipes and silencers/mufflers; with originals, there was a slight noise reduction but today that more-likely depends on the maker of a given silencer/muffler.

don't see it on the stock exhaust.
There's a link on all '69-on twin exhaust systems.
 
I have tons of spare carb parts.

grandpaulz athot maildot com

Send me a list of what you need, fire sale pricing, you pay postage.
 
Don't miss Grandpaul's offer...grab it while the offer is hot!
 
I have tons of spare carb parts.

grandpaulz athot maildot com

Send me a list of what you need, fire sale pricing, you pay postage.
Well damn already ordered a whole new carb last night. Should have been patient. I should know by now forums like this always have someone with spare parts
 
If your order isn't shipped yet you may be able to cancel it still.
 
Just a quick update. The engine isn't siezed. However it was sticking in some spots. So drained the oil. Added some oil inti the cylinders. And rotated the engine a good amount. Got it to stop sticking. It was stuck in neutral as well but managed to break it free, I assume the clutch plates were probably stuck

Kickstart return seemed gummy. Pulled the gearbox cover off. Found the spring return plate was warped so going to order a new spring and plate, transmission looks very clean inside. I assume it was rebuilt by someone at some point but don't see any where on the visible parts. Attached a photo.

Wiring is just a mess. Ignition coils has some corrosion dust on them. Rectifier is broken. Thinking if just doing a complete rewire of the whole bike. With my trade I do a lot of wiring and actually really enjoy it so not an issue there.

Any suggestions for where to get electrical parts for the bike would be appreciated.
 

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Nice project!
If you're located in MA, USA the Choppahead cycles shop and Hutchinson cycles are local to the state and they carry parts for the older Triumph bikes. You've also got Lowbrow customs, Factory metalworks, British cycle supply, Walridge motors to name a few.
Suggest pitching some of the old Lucas components and going with EI if you're re-wiring... Pazon, Boyer or other ... makes things more reliable and better performing in my opinion and experience. There are wiring diagrams available online for positive or negative earth options ... battery or no battery etc.
 
I don't know much experience you have with vijntage Triumps; but their clutches are prone to sticking. Aa a matter of routine, I put mine in neutral and with the ignition off, I kick start it until the kick start move freely. Then I start the bike.
 
I don't know much experience you have with vijntage Triumps; but their clutches are prone to sticking. Aa a matter of routine, I put mine in neutral and with the ignition off, I kick start it until the kick start move freely. Then I start the bike.
Tiny bit of experience with vintage triumphs. So learning a lot with this project. That's exactly what I did. I came across a post on here recommending that so gave it a try.
 
engine
rotated the engine a good amount.
Stop doing this until you have added oil in several other places:-

. When the engine is running, camshafts and followers are 'splash lubricated'- by oil that drains into the crankcase from higher up the engine, picked up by the spinning crankshaft flywheel and flung around the crankcase. Simply "rotating the engine" doesn't do this, so camshafts and followers could be rotating/rubbing without oil.

. Also when the engine is running, oil is pumped to the rockers and valves in the cylinder head. Again, simply "rotating the engine" doesn't do this, so rockers and valves could be moving without oil.

. Remove the four valve inspection caps from the rocker-boxes, use an oil 'squirt-can' with a long spout to squirt engine oil liberally over valves, springs and rockers. Also squirt liberally at the rocker ends on the tops of the pushrods, some of the oil should then drain down the pushrod tubes to the cams and followers.

. Remove the two domed nuts from the ends of the rocker shafts, use the 'squirt-can' to push oil into the rocker shafts - required is steady pressure on the 'squirt-can' lever for a period and you might be rewarded with oil dribbling from between rockers and washers.

Later, before first starting the engine, pour a full pint of engine oil into the primary chaincase the day or night before the first start. A full pint is more than the chaincase requires normally, the excess will drain into the crankcase; when the engine starts, the oil will be picked up and flung about by the flywheel, lubricating 'splash-lubricated' bearings before oil drawn from the tank and pumped through the crankshaft. Also, oil returning to the tank will show sooner than waiting for oil drawn from the tank and pumped through the crankshaft to drain into the sump, cutting the time you hold your breath after starting the engine before scavenged oil reappears in the tank ...

Wiring
where to get electrical parts
If you want a complete harness off-the-shelf, British Wiring do the best in the US. I strongly advise against "Genuine Lucas", which is nothing of the sort.

However, British Wiring is only "the best" if you ask and they agree not to supply an exact copy of a 1971 T100C harness but to incorporate certain changes to fix original '71 cost-cutting and/or make it easier to connect late 20th century electrical components. Aiui, BW will make changes only sometimes, so you have to ask; if they won't make the suggested changes for you, as you're happy with wiring, "the best" is more-likely diy from components (which'll also be cheaper).

Desirable changes are:-

. Brown/Blue wire from battery negative to ignition switch in 28-strand. '71-on standard is 14-strand, its 8.75A rating is exceeded by the standard alternator output above about 2,000 rpm ...

. Brown/Blue wire also without connections for original rectifier and Zener diode (latter in the finned casting attached to the front of the lower fork yoke). Late 20th century replacement is an electronic combined regulator/rectifier, its DC output wires connected directly to corresponding battery terminals.

. Brown/Blue wire also without fuse/holder.

. Fuse/holder in a 28-strand Red wire, that being the only Red wire from the harness Red wires network attached to the battery positive terminal.

. White wire from ignition switch to junction with individual components' White wires also in 28-strand.

. If fitting an electronic ignition:-

.. Second White/Yellow wire and terminal by the coils deleted. Two White/Yellow wires and terminals are only required with points ignition (one White/Yellow wire is connected to each coil's negative terminal). With electronic ignition, only one White/Yellow wire and terminal is required, for connection to the ignition 'box'.

.. Second Black/White and Black/Yellow wires deleted. With points ignition, one each of Black/White and Black/Yellow wires connects a coil's positive terminal with its corresponding points; the second of each Black/White and Black/Yellow wires connects a coil's positive terminal with one of the condensers (inside a rubber and metal box normally mounted under the forward fuel tank mounting to the frame). Condensers aren't required with electronic ignition, so one each of the standard Black/White and Black/Yellow wires from the coils' positive terminals isn't required. Similarly, the Red wire that originally connected the condensers box to the harness isn't required.

If you decide to diy the harness, while BW's website looks like they can supply everything required, regrettably there are some significant gaps - e.g. (currently?) they don't list crimping tools for any of the listed terminals ... - while some other components are expensive.

If you look more widely than BW, consider Autosparks (BW's supplier, but a greater selection of components than BW) and Vehicle Wiring Products in the UK - not as daft as it might look initially for a large order, as you wouldn't pay the UK equivalent of sales tax, and carriage to the US is significantly less than the likes of the USPS screw you to send stuff out of the US.

Btw, if you buy from Europe or British Wiring, one thing you might wish to be aware of, despite BW including "Gauge" (AWG) is some of its wire descriptions, all wire is metric - each strand is 0.3 mm. OD, 14-strand has a 1 sq.mm. conductor cross-section, 28-strand is 2 sq.mm.

Rectifier is broken.
As I say, it's been common for decades to replace it and the Zener diode with a combined regulator/rectifier. My preference is for one of only two - Podtronics POD-3P or 5-PIN Voltage Regulator RectifIer for HONDA CBR600/900RR 1100XX 96-99 97 98 NEW | eBay plus 5 Way Regulator Rectifier Male Plug Connector For HONDA VT750 Shadow 750 400 | eBay.

As you can see, both are for 3-phase alternators, while the alternator on your bike is (was originally) 2-wire single-phase. Reason is, if/when the bike needs a new alternator, or you want to upgrade, all alternators (stators) are a similar price, so that makes a (high-output) 3-phase the best value. In that case, I'm guessing you wouldn't want to have to upgrade the reg./rec. as well when, right now, a single-phase alternator can be connected to a 3-phase reg./rec.?

As you can also see, big difference in price. Podtronics is US made, been around for decades, US-based back-up if anything goes wrong. Ebay ones have been around for a decade to my knowledge, rock reliable, but you can buy three or four for the price of the Pod.

As I say, simply connect the DC wires of each directly to the battery terminals - Red to battery positive, Black or Green to battery negative. I include a blade fuse/holder in one of the wires.
 
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Awesome project!
I've seen a few older Triumph's, 650cc, 500cc ect being 'bobbered' . Spares for the style should be easy enough to get ive been told about Dragonseating for the seat and custom mudguards from classicbikeshop.
As long as its going to be used it don't mind the style really!
Good luck with the project :p
 
Excellent post Rudie TUP TUP
 
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