1962 Triumph 5TA speed twin - Wiring trouble - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 6 (permalink) Old 07-21-2009, 03:49 PM Thread Starter
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1962 Triumph 5TA speed twin - Wiring trouble


I recently bought a '62 Speed Twin that had been sitting in a shed for two years. The PO had bought with the intention of restoring it but never got to work on it.

First thing I noticed was that the wiring was a mess. A serious mess of wires put together with tape and the likes. So I replaced all connectors and almost all wires and now the lights and switches work.

BUT - I can't get spark. And in my manual I can only find descriptions and diagrams of twin coil models with breaker points in the side case. Mine has the Lucas distributor ( I think it's called 18D2) and only one coil and one breaker. I have opened the distributor and it looks clean.

To to test the ignition system I tried to set it up as in the image but still no spark. Can anyone see what I'm doing wrong? Does the rectifier and zener have to be connected for it to work?

By the way, first time I connected the battery I couldnt see which wire was positie and negative so I put them on wrong and one wire got really hot. I may have fried something?

And, does anyone have a diagram for a 5TA?

Thanks a lot. I know it's a lot of questions but this is my first brit bike :-)
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post #2 of 6 (permalink) Old 07-21-2009, 04:17 PM Thread Starter
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maybe I found the answer

just found this http://www.triumphcomehome.com/Coil%20Test.pdf

looks like I can find a lot of explanation there. I'll be back
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post #3 of 6 (permalink) Old 07-21-2009, 05:54 PM
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trump elecs

Hi - I have a 62 T100SS which needed a new loom and much other work but I think I have it running sometimes (it has a mystery fault; there is fuel, spark etc but it ocasionally wont run....). This has lead to my trawling the net and people's brains extensively. There is a pdf I have uploaded and attached it here. It concerns much about what you are querying. If you think you fried something, it might be as well to hot wire it just to eliminate that probablity.

Fit an easily removed wire from the battery live to the + on the coil. Rather thatn trying to start it, just put a working plug from anything in one of the caps - then the other to be sure. If there is nothing (you sshouldn't need the switch on for that test) you might try either a voltmeter or light bulb (I image you are on 6v?) at the distributor live feed. With the ign on, if there is no reading/illumination, trace that wire back to the coil. Test that wire for contuity. And repeat the power test with the feed to the coil (I doubt the coil will be burned out - if it is CHinese it may be substandard so dig deep and fork out for a decent one - trisupply seem OK).

If there is no juice there again test the wrie for continuity and trace it back to the switch - keep repeating these tests until you reach the battery. If all the wires check out OK, (zener and stuff i beleive are all to do with charge, not ign or light etc) then it could be the coil, condesor whatever - test one at a time by substitution. I have found that while I got power to the coil, the HT connection was crap so I fitted a brass screw into the wire.

So it goes on really - let me know how you get on or if owt still confuses. I have found various sites & etc that may help. As for me, I went 12v but it didn't solve any of the bike's inherent probs. Maybe soon.
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post #4 of 6 (permalink) Old 07-30-2009, 04:27 AM Thread Starter
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Electricals sorted!

Hello again,

Thank you very much for the help. I did as suggested, hooked the ignition up without the charging system (by the way its a 12V), which made things a lot more simple. After tinkering a bit with the wires and studying the pdf closely I got spark! a weak one, but it was there. I then cleaned the plugs, which made it a bit better but I will replace them anyway just to be safe.

I then sorted out the throttle cable, which was too short and left the throttle half way open and with some start gas, it fired right up! It doenst idle but I think that's just a matter of adjustment.

I still need to connect the ign. system to the charging system, and see if it's working but so far I'm happy to hear it running

Now, I just need to aliminate clutch drag. As soon as i try to put it in first gear it dies. I probably need to change the oil in the primary drive - does anyone know how much oil I should put in there and what type is best?

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post #5 of 6 (permalink) Old 07-31-2009, 04:45 AM
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Running - wiring trouble

Hi, glad the info helped. I found another link that can be useful for things trump; http://www.britishcycle.com/help.htm

I hope you just took a wire from the battery to the coil(s)? Doesn't really matter but some components are sensitive to prolonged abuse - usually more modern electronic things rather than zener diodes whatever. The small spark could be indicative of a poor earth, low battery - as you're on electronic ignition there isn't much else. Sparks can look poor in certain light - if it runs it can't be too bad.

I'd be inclined to check even things that look ok (earth connections -dismantle, clean) and get the voltmeter/ammeter on others. The result of your test shows that there is a fault between either the battery and the ignition switch, with the switch itself or with something (a wire or connector) between switch and coil(s). If you don't have a volt meter, a working 12v bulb will help trace it by wiring it to the item you are testing and earth - with the ignition on.

Got mine running again at last - found several shorts around the points - and they weren't closing - and the distributor wasn't seating so the timing was slipping.

It still cut out and a quick natter with Oliver at TRisupply suggested petrol cap vent. A test run disproved this (and I got a face full of fuel when I revved it sans tank lid). Notably when it stutters to a halt there is a lack of compression. I think (and hope) I have simply gapped the rockers too tight. Everything crossed... (why do we get an oriental holding our flag?
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post #6 of 6 (permalink) Old 07-31-2009, 08:57 PM
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Originally Posted by T100SS View Post
Everything crossed... (why do we get an oriental holding our flag?
T100ss san,

Nani? Kare no Yamaha ga kowareta otobai o arimasu. Kare ga josha o irimasu.

What? His Yamaha is broken. He needs a ride.

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