Other Stuff > Desperately Seeking!!

Wanted CB 400 4 coils for an F2 1977

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Ken4004:
Hi Ash thanks for the advice, from what I can see the descriptions of some of these HT leads don’t give a great deal of detail, do you think the bright coloured cables are predominately silicon coated ?

I’ll check the specs on the epoxy resins to ensure good electrical properties, just trying to find a small quantity as I don’t think I would ever use a litre can of it.
I have seen the sachets where once you open it you need to use it unless I can find a small tin of epoxy + hardener.

Oddjob:

--- Quote from: AshimotoK0 on May 06, 2026, 08:23:27 AM ---I wouldn't use silicone HT lead on the coil fix as I don't think you would get decent bond with the epoxy.

--- End quote ---

Sorry Ash but explain that a little please.

AFAIK the main supply of HT leads these days is silicone sheathed. Not 100% sure what Honda used back then but it seems silicone is the stuff most commonly used these days.
I can understand your concern regarding the adhesive quality or lack thereof in this case. But I’m a little confused as to why you think this is a cause for concern. The new lead is soldered to the stump of the old lead, so I’d imagine just that would mean it can’t be pulled out easily. The epoxy I understood was just there to fill the hole you need to make to gain access to the old core of the old lead. If it also grips the outer sheath of the new lead that’s a bonus I suppose. I always smeared silicone sealant on the outer sheath where it enters the coil body in order to prevent water ingress. You’d imagine silicone would grip silicone wouldn’t you? Or am I wrong?
My set of coils is still only half done as my illness last year just stopped everything so I’m fortunate in some respects that I can alter mine without too much trouble. I was intending to fill the hole with the epoxy you sent me so it was almost flush with the body of the coil, then overfill a little with something like Araldite and then dress this down until flush and then spray Matt black in order to blend the repair in.

Have I got something wrong? Or just misunderstood your concerns here.

exvalvesetdabbler:
Nothing much bonds to silicone apart from silicone. Silicone doesn't have much structural strength  either.

The original ht leads look like pvc or similar thermoplastic with a rubber jacket.

Getting resins to bond with other materials is shrouded in mystery.  A lot of the primers used in industry are obviously proprietary.  In critical applications we sometimes had no option but to buy the molding kits with all the needed resins and primers.  Without the right resin and compatible primers the bond would usually fail, usually when in deep water.  We were bonding polyester and polyeurothane sheathed cables to stainless using a rubber compound. For less critical applications ie
Prototyping cable harnesses epoxy seemed to bond with most stuff.  Low energy plastics were the worst, polythene or polypropylene.


Regards
Dave

AshimotoK0:
I think Dave has pretty much answered you there Ken.

I usually use 7mm PVC cable or Hypalon and abrade/degrease the surface. Hypalon isn't supposed to good for bonding to rigid epoxy but I have abraded it and found it to be OK with the RS adhesive. I don't think the original PVC cable 'bonded' well to the plastic Honda used anyway.

Ken4004:
Ok thanks Ash I will therefore get some pvc ht leads instead.

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