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Coil?

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Pauarc:
https://youtu.be/W4HRPsTPl0A?si=gnP8oVxs_RqP18eG
Hi Martin this may help
Paul

Martin6:

--- Quote from: Pauarc on April 08, 2025, 05:23:01 PM ---https://youtu.be/W4HRPsTPl0A?si=gnP8oVxs_RqP18eG
Hi Martin this may help
Paul

--- End quote ---
👍

Martin6:
All 12v feeds to the coil are reading fine. Bullets are clean and tight. The resistance checked out fine on primary and secondary, then started the bike and it ran on all 4. Took it for a ride and it cut out on 2 and 3 again before I got half a mile.

I think it is the coil, I should have retested the resistances while still hot, but I'd already ordered a new coil and 2 new plug caps while I was at it, from David Silver. I'm hoping to ride tomorrow with a mate and I didn't want delivery to hold me up.

New coil arrived just before lunchtime today, 24hrs on std delivery. Was impressed. I was expecting to shove it on in 30 minutes to an hour. Took me over 3 hours. It is a pattern part and the coil mount holes are further apart than the bike frame's bracket which then interferes with the front spacer that sits on the mounting bolt. Also, the 12v feed terminals are spade connectors on the new coil, they are longer than the original arrangement, so interfere with the bike's frame. Also, the 12v connectors are both male, rather then one being female.

I made up a temporary extra bracket extension, out of a large diameter disc washer, drilled with a second hole and filed down to be bolted onto the frame bracket and then the new coil onto the extension. I don't generally have metal offcuts lying around, so I had to make do. It's solid though and doesn't interfere with the fuel tank. I had a sheathed double female connector, so that sorted the male to male connection.

But a simple job had become frustrating. I rang David Silver to check they'd sent the correct part. They had. They knew about the mounting holes being incorrect, but had never had anyone raise the incorrect bullet connection. Their view was it's a pattern part, not OEM. I could send it back for a refund if I wished. I asked him to add a note to the item on their website, to warn customers.

Anyway, bike started up from cold on all 4 nicely. Needed to feed and walk my dog, so only had time for a 20 minute run, which was fine.

I guess, no earth shattering learning here. 1. Old coils can seem OK but not cope when they warm up, 2. Pattern parts may have used a different pattern.

Sorry, bit lengthy!  ::)

McCabe-Thiele (Ted):
I'm sure you have, worth mentioning though, the coils should be marked for polarity and connected appropriately.

The coils will still work but not strictly as they should, be interesting to know if the coils are branded?

K2-K6:
Hopefully you'll get a good and uninterrupted run out on today.

Pinpointing the real cause always adds to personal knowledge store, plus research as you've done here just fills in gaps with a little more confidence in your looking after it.

To be fair, these original coil are fantastic in their reliability, possibly better than most in construction.  They do however eventually succumb to flexing around the HT lead to coil area, ultimately to crack or disconnect the HT route continuity.

There's, on here, Ash's coilfix method to replace the HT and reinstate them.

It's possible that if the HT are trimmed to fit new caps over the years, then the eventually get too tight when pulled to get them onto plugs that may play a part in this effect.

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