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#847750 05/02/21 6:54 am
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I have fitted two sets of coils onto my 650 now with the same result: neg power to -/SW terminal and points/ condensers to +/CB terminal. When I switch on the coils get warm but with a test light I have nothing if I connect from +/CB to earth. Surely there should be continuity here? How are they getting warm?? Does this indicate a faulty coil which is my assumption at this stage?


1968 T150/TR6R
1970 TR6C
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Hi,

You'd do better with an Ohm-meter or multi-meter set to Ohms:-

. one meter lead end each on SW and CB terminals, depending on coil make, '12V' coil, meter should display between 3 and 4.4 Ohms; '6V' coil, meter should display between 1.5 and 2.2 Ohms;

. one meter lead in the HT terminal, other meter lead end on each LT terminal in turn, meter should display around 5,000 Ohms;

. one meter lead on the coil case, other meter lead end on each terminal (LT and HT) in turn, meter should display very high (tens of thousands) Ohms or infinity.

Originally Posted by tiger_cub
coils get warm but with a test light I have nothing if I connect from +/CB to earth. Surely there should be continuity here?
There is, the coils are getting warm. smile

The points are simply a switch, not a resistance, the coil's the resistance in any ignition circuit. Assuming standard "positive earth", the potential difference (unit Volt) is the same from coil CB to battery +ve; because the p.d.'s the same, there isn't anything to 'power' the test light bulb. Try connecting your test light between points and battery negative?

Hth.

Regards,

tiger_cub #847759 05/02/21 10:01 am
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Coils measure 4.2 - 4.6 ohms (One is 6V I just discovered so measures 2.1 ohms). i will need to get another. I was assuming the test light would just be a parallel circuit to earth. I will measure the HT side next.


1968 T150/TR6R
1970 TR6C
tiger_cub #847838 05/02/21 10:20 pm
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All the 12V coils test as around 4800 ohms HT to other connections. Also got circuit light batt -ve to coil +/CB. Looks like all is well....


1968 T150/TR6R
1970 TR6C
tiger_cub #848020 05/04/21 12:30 am
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As they are Wipac coils, they have screw in acorn nuts which don't seem to be able to make a good HT connection, I will just have to keep trying to get that with metal spacers and washers!


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Originally Posted by tiger_cub
I was assuming the test light would just be a parallel circuit to earth. I will measure the HT side next.
It is a parallel circuit, but it's parallel to a short circuit so no current flows through the lamp unless that set of points is open.


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I'm now having an issue with the 6CA points setup. I get a connection with my test light from battery neg to the points wire/ coil CB even when the points are are open. All the nylon spacers are in place and I just can't see where the short would be. I have disconnected the condensers, it doesn't make a difference. Any ideas?


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1970 TR6C
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Now I know what it is - the points spring has been made badly and contacts with one of the baseplate screws. I re-bent them and all is good now....


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Hi Tiger_cub, Good you found the crooked spring. occasionally I’ve seen that. Even back in the day with original points.

Sometimes after riding & spring heats/cools it may want to go back to its old ways. One of mine did that & I had to tweak it again. Was good ever since.

After riding a bit give it a quick look.

It didn’t want to line up right on install. Like the loop over stud was rolled crooked. I tweaked it. Was fine a few days. Then no spark one side one morning. Was fine last night. Inspection showed spring had moved. Another tweak. Been good since. Same points still in at 36k miles. I put them in at 6k.
Don


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I like using the 6CA plate in my Cubs as well. Fine adjustments are much easier to make. However, I have found that that the additional plate on the 6CA forces the points cam follower a small bit off the top of the points cam but not a real issue. Cub On!


Geoff Patrick
geoff@americantriumph.com
FLY AMERICAN TRIUMPH!

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