Dyna coil

[davidcouzens]

hi anyone had a problem with a dyna coil burning out? Could it be just bad luck or something else other coil is fine and I've swapped the wires on the sender unit and seems to be sending a spark from both sides.?

[zed1015]

Has it been shorting on the mounting post ?
Dyna coils are not polarity sensitive.

[davidcouzens]

Hi Rob I don't think so had the ignition for 3 years and have mounted them with nylon washers as spacers on 6mm long screws never gave me any trouble before.

[davidcouzens]

this is the other side the duff coil was mounted the same

[warren3200gt]

It looks like the coil core heat sink bar is not actually able to heat sink to the frame and has caused the coil to overheat.
Zooming I'm on the pic shows the nylon Bush going through the core bar and the cross head is seperate from the core bar also which means the bar is isolated and unable to dissipate core heat unless that's a washer under the cross head?
That'll burn out the coil in a pretty short time frame.

[davidcouzens]

Thanks Warren
That is a steel washer under the cross head screw. I used the nylon washers as the slot pan screws that connect to the coils are close to the bikes frames and can touch and short to keep them away from the frame. So I guess I need to somehow allow the metal heat sink to dissipate heat through the frame?

[warren3200gt]

The core should dissipate through the core bar then through the mount bolts the directly to the frame. Obviously to do this no part in the chain can be thermally isolated. Contacts between each part in the chain should be clean metal to metal and the largest contact area possible to maximise heat dissipation.

[davidcouzens]

I can dispense with the nylon washers and use some extra half nuts on the screws to mount the coils in the current position

[warren3200gt]

You can but then wrap the mounts with insulation to ensure the Dyna terminals can't arc across to the mounts

[davidcouzens]

Yes a good tip thanks again

[warren3200gt]

Heatshrink works well.

[davidcouzens]

So got a replacement coil and changed the mounting arrangements on both to this. Bike fired up and hopefully no further problems. Thanks for the help all.

[warren3200gt]

Assuming the spacer is insulated from arcing then to be 100% confident I would also insulate these points. Easiest way would be to cover or paint the terminal connections. Electricity has a knack of finding the route of least resistance to ground, especially when damp.

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