Honda-SOHC
Other Stuff => Desperately Seeking!! => Topic started by: Ken4004 on May 03, 2026, 06:41:21 PM
-
If anyone has got a pair of coils for a 1977 CB 400 4 , not worried if the cable are damaged as long as the coils are functional.
I want to replace the cables on my original coils and just want a spare set so I can fit them to my bike while repairing my originals.
Thanks regards Ken
-
Don’t worry I am going to buy some new coils from DS , it’s not really worth the effort to try and refurbish a set of coils.
-
Just be careful if you're using standard points. I had a set of coils off a scrap 400, they looked the same but had detachable ht leads and a much lower resistance. They ran fine but caused the points to get pitted quite quickly. Probably for a newer bike with electronic ignition or a ballast resistor.
Dave.
-
Thanks Dave I am going to get the DS coils so I know where a I am
-
Not wanting to sound defeatist here Ken but just because it comes from DS doesn't mean it's perfect for your requirements. Lots of reports on the forum of DS stuff being either wrong or poor quality.
Your initial idea was a much better one IMO, the original Honda coils are almost bullet proof, the Achilles heel being the leads of course. The Ash fix cures that problem and should be good for many years and then can be done again if it ever needs it. Perfect fit, correct connectors etc. Ok it's more work but it's cheaper and better in the end.
Plus if your a bit odd like me you can substitute the leads for another colour. My CB1300 has red leads for instance and I much prefer the look of those so I've done a set of 500/550 coils with red leads, along with a red silicon outer sheath like the OE leads and the numbers on the leads. The old numbers slide off the old leads with a little care so can be reused.
-
Does that mean the yellow 400f should have yellow ht leads to signal it's elevated status?😄
Dave
-
Why not? It would be different
-
Don’t worry I am going to buy some new coils from DS , it’s not really worth the effort to try and refurbish a set of coils.
I'd heard a rumour that the DS coils are made by the original supplier to Honda.
-
If it was the OE manufacturer Ted you’d imagine they’d still have the original specs to hand, if so why are the wires fitted using flat spade connectors instead of the original bullet connectors? Why no manufacturers stamp on the body like the OE ones? Why no cylinder numbers or even the leads cut to the right length?
To me it sounds like the typical pile of BS that DS spout in order to get sales. They still make a profit even if it’s returned.
-
Not wanting to sound defeatist here Ken but just because it comes from DS doesn't mean it's perfect for your requirements. Lots of reports on the forum of DS stuff being either wrong or poor quality.
Your initial idea was a much better one IMO, the original Honda coils are almost bullet proof, the Achilles heel being the leads of course. The Ash fix cures that problem and should be good for many years and then can be done again if it ever needs it. Perfect fit, correct connectors etc. Ok it's more work but it's cheaper and better in the end.
Plus if your a bit odd like me you can substitute the leads for another colour. My CB1300 has red leads for instance and I much prefer the look of those so I've done a set of 500/550 coils with red leads, along with a red silicon outer sheath like the OE leads and the numbers on the leads. The old numbers slide off the old leads with a little care so can be reused.
Hi Odd Job your right I should have a go and repair my own, what do you think of yellow leads for a yellow bike or is that going to far alternatively blue leads would match the blue stripe on the tank !
I would however like a donor set of coils do I can still ride my bike whilst repairing my old ones.
Where would be the best place to buy good quality leads and plugs ? , there are so many people selling them with as you would expect varying in quality.
If I am going to the trouble of repairing the old coils I want to use good quality materials.
-
Try the green spark plug company. Used them a lot and always found they sell decent stuff.
Little tip. If buying plugs consider buying ND plugs instead of NGK. Lots of reports of fake NGK plugs but none of ND plugs. Honda used both makes back in the day and there wasn’t much between them to be honest.
Yellow leads? Yeah why not. I did have some spare coils for the 500/550 but without looking I couldn’t say for certain if they are the same as the 400 coils.
-
I have just been looking for adhesive at RS , this is what I have found but says only good for up to 120 deg , I wouldn’t have thought it would get up to that temp even though it is above the engine.
-
Try the green spark plug company. Used them a lot and always found they sell decent stuff.
Little tip. If buying plugs consider buying ND plugs instead of NGK. Lots of reports of fake NGK plugs but none of ND plugs. Honda used both makes back in the day and there wasn’t much between them to be honest.
Yellow leads? Yeah why not. I did have some spare coils for the 500/550 but without looking I couldn’t say for certain if they are the same as the 400 coils.
Blimey your up early I thought is was just me who was mad, thanks for the feedback I’ll take a look
-
I used a lot of electrolube black epoxy potting compound at work for potting up underwater cable splices and connector to cable terminations. Comes as a split pouch where you pull off a crimp and mix the contents of the two sections. No mess. It's a one shot deal though, you have to use it or bin it. One trick was to put it in the fridge to extend the pot life a little.
Stays runny for about half hour and rock hard by the next morning.
I thing the smallest we used was RD Pro 50 g which was handy for small jobs.
Dave.
-
That’s the same stuff I used to encapsulate new lead join, then reshape to original profile with milliput 2 part putty. Can be sanded and painted too. Yellow leads? Why not, I’ve just ordered blue but don’t even know what colour the bikes going to be yet!😳
-
Oh dear, what have I started. 😀😀
As for being up early, in fact I hadn’t even gone to sleep yet, my body clock is all messed up since I got ill last year.
-
That’s the same stuff I used to encapsulate new lead join, then reshape to original profile with milliput 2 part putty. Can be sanded and painted too. Yellow leads? Why not, I’ve just ordered blue but don’t even know what colour the bikes going to be yet!😳
Blue sounds nice as well again matches the stripe on the tank, well I need to make a decision, where did you get your leads from ?
-
A slight mod I made to the Ash fix on coils was to fit a 1m circle of lead instead of fitting 2 separate leads. That means you can fix the coil in place, I fit mine backwards so that water can’t be forced down the lead opening by wind pressure, this tends to mean you need slightly longer leads but even standard lengths fit. However you can now route the leads over the top of the engine using clips on the camcover bolts to secure them and get the leads to approach the plugs from the rear instead of the front. Looks much neater, no chance of melting them on the exhaust pipes, especially if the lead is disconnected for servicing etc. Use a long straight HT cap for the inner cylinders and long right angled for the outers.
You cut the lead when your satisfied with the routing.
-
A slight mod I made to the Ash fix on coils was to fit a 1m circle of lead instead of fitting 2 separate leads. That means you can fix the coil in place, I fit mine backwards so that water can’t be forced down the lead opening by wind pressure, this tends to mean you need slightly longer leads but even standard lengths fit. However you can now route the leads over the top of the engine using clips on the camcover bolts to secure them and get the leads to approach the plugs from the rear instead of the front. Looks much neater, no chance of melting them on the exhaust pipes, especially if the lead is disconnected for servicing etc. Use a long straight HT cap for the inner cylinders and long right angled for the outers.
You cut the lead when your satisfied with the routing.
Sorry not quite sure what you mean by 1M circle of lead , are you saying you get a loop of lead 1 metre long and solder the middle of the lead at one point at the coil as per picture attached ? I managed to find a wiring diagram of the coil, do is this what’s inside the original coil a piece of wire the length of the coil connected in one place to the middle of this wire the the two ends connected to one of the ignition coil ht leads ( I hope you understand what I am saying)
-
There are 2 ht leads coming out of each coil. 1-4 and 2-3 usually. Now you get a 1m length of ht lead. Do the first connection to say the number 1 lead. You’d normally measure how much of the length you’d need and cut the lead to this length with maybe a bit extra, just in case. Now you’d do the other one, number 4. Again after attaching it you’d measure and cut. The problem being if you get it wrong and you cut it too short you’re going to have to redo that lead. My idea was to do the first connection and then go right to the other end of the 1m lead and use that to connect to number 4. So you’re left with a lead going from number 1 port to number 4 port. Only after you have fitted the coil in place and routed the wires as you want them do you do the cut. One lead is always longer than the other so there is no chance of getting it wrong. Leave each lead a few inches long so you can cut and trim a little as time goes by. It wastes a little of the lead but that’s better than risking cutting too short.
-
There are 2 ht leads coming out of each coil. 1-4 and 2-3 usually. Now you get a 1m length of ht lead. Do the first connection to say the number 1 lead. You’d normally measure how much of the length you’d need and cut the lead to this length with maybe a bit extra, just in case. Now you’d do the other one, number 4. Again after attaching it you’d measure and cut. The problem being if you get it wrong and you cut it too short you’re going to have to redo that lead. My idea was to do the first connection and then go right to the other end of the 1m lead and use that to connect to number 4. So you’re left with a lead going from number 1 port to number 4 port. Only after you have fitted the coil in place and routed the wires as you want them do you do the cut. One lead is always longer than the other so there is no chance of getting it wrong. Leave each lead a few inches long so you can cut and trim a little as time goes by. It wastes a little of the lead but that’s better than risking cutting too short.
Hi Odd Job thanks for the clarification I now know exactly what your getting st regards Ken
-
Like you, my name is also Ken, just for future reference.
Glad you understand now. Before you cut the leads try a test fit with the leads coming out towards the back of the bike instead of pointing towards the front. I found it cured the arcing problem these leads had due to water ingress, the wind used to force water down the lead and into the coil entrance and also down the rubber collar on the top of the ht cap as this was also facing forward. Never had a misfire in the rain after doing this mod. It did mean though that number 1 lead went to number 4 cylinder but with the wasted spark system Honda used this isn’t a problem.
-
Hi Ken
Thanks for your advice can’t wait to get stuck in after my holiday.
Regards Ken
-
That’s the same stuff I used to encapsulate new lead join, then reshape to original profile with milliput 2 part putty. Can be sanded and painted too. Yellow leads? Why not, I’ve just ordered blue but don’t even know what colour the bikes going to be yet!😳
Blue sounds nice as well again matches the stripe on the tank, well I need to make a decision, where did you get your leads from ?
Hi Ken, ordered ht cable from these guys.
https://www.pedparts.co.uk
-
I wouldn't use silicone HT lead on the coil fix as I don't think you would get decent bond with the epoxy.
I only quoted the RS components epoxy as we use it where I work it has a quoted high dielectric strength ...but you could use another liquid epoxy if it has a decent electrical spec. It's a great general purpose adhesive though and it can be filled with aluminium powder, silica etc for a whole variety of uses.
-
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.
-
I wouldn't use silicone HT lead on the coil fix as I don't think you would get decent bond with the epoxy.
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.
-
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
-
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.
-
Ok thanks Ash I will therefore get some pvc ht leads instead.
-
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.
I have found this potting compound on eBay 50 ml so looks like it fits the bill
-
As it turns out Ash I looked back at my order from the Green Spark Plug company and it turns out I actually ordered both red and black 7mm PVC HT lead. Not silicone. So hopefully that should work just fine.
-
As it turns out Ash I looked back at my order from the Green Spark Plug company and it turns out I actually ordered both red and black 7mm PVC HT lead. Not silicone. So hopefully that should work just fine.
Your idea of turning coils around I think was used by dispatch riders in the 70's Ken. Yea ... I got mine from Green Spark Plug Co. too.
-
Oh, I’ve never heard that before Ash. And here was me thinking I’d invented that mod. Or maybe they copied it off me 😀😀😀
-
I wouldn't use silicone HT lead on the coil fix as I don't think you would get decent bond with the epoxy.
I only quoted the RS components epoxy as we use it where I work it has a quoted high dielectric strength ...but you could use another liquid epoxy if it has a decent electrical spec. It's a great general purpose adhesive though and it can be filled with aluminium powder, silica etc for a whole variety of uses.
Hi Ash is this the epoxy you used on your coils ?
Regards Ken
-
I wouldn't use silicone HT lead on the coil fix as I don't think you would get decent bond with the epoxy.
I only quoted the RS components epoxy as we use it where I work it has a quoted high dielectric strength ...but you could use another liquid epoxy if it has a decent electrical spec. It's a great general purpose adhesive though and it can be filled with aluminium powder, silica etc for a whole variety of uses.
Hi Ash is this the epoxy you used on your coils ?
Regards Ken
Yes but it's a bit expensive to just do one set of coils plus we use it at work.
-
Hi Ash they are all expensive but as you say I might use it for other uses in the future, by the way who do you work for and what do you do ?
-
Hi Ash they are all expensive but as you say I might use it for other uses in the future, by the way who do you work for and what do you do ?
I am an electronics design engineer for these guys but I only do 1 to 2 days per week now.
https://www.waterhydraulics.co.uk/
-
Thats interesting work Ash and a bit of a coincidence as I am also a hydraulics engineer myself but now semi retired and working for myself .