Let's talk coils... and spark!

[Bob H]

Wow, your post with images showed up as I was creating my post.

Left coil #1

In your photo it is on the left, but sitting on the bike it is on the right. So that throws in a bit of confusion there - but I understand what you are saying.

Left goes to spark plug 1
Right goes to spark plug 4

I don't think that matters. It is my understanding that when the coil sends it's output, it goes to both plugs at the same time. I would just go with the longer lead going to the furthest plug as a guide.

Sounds an odd firing order to me that 🥴

If my theory is correct (that the coil fires 2 cylinders at once) then you can't really view this as a "firing order".

[Larry Fine]

If my theory is correct (that the coil fires 2 cylinders at once) then you can't really view this as a "firing order".

Your theory is correct. It's called a "wasted spark" system, but the actual ignition is what counts.

[ThePowster]

Guys, thanks a lot for your input, this really helped me and gave me the confidence to give it a go.

So I installed the coils, hit the starter button and ...nothing. So I hit it again, nothing.. Then I figured I'd try and bump it rather than flatten the battery. A little push, jump on the seat, into first and clutch out and boom she fired into life 😁

I put her on the side stand and just observed for a moment.

First I saw more white smoke than I've ever seen before, that's probably the 4th cylinder now firing 😄 but she sounded deeper too. 

I took the choke off and rode her around the carpark, baring in mind I have no brake line on the bike 😬 anyway she felt alright.

She wasn't pulling or revving like I wanted but the choke had only just come off and the engine was cold still. I'm hoping once she's warmed up a bit she'll then rev freely.

I've other parts of the electrical system to test but I can tick off coils, HT leads and caps for now at least and move onto other aspects of the electrical system.

V happy just having that little go. I've got a 2007 ZX-14 and honestly I'd be happy just riding the Nighthawk, what it doesn't have in speed it makes up for in character and I love it 😁

Thanks again for all your help and images and I hope this also help others. The firing order made sense too now thinking about how a crank works 👍

[Pete in PA]

You can get a stronger spark also by lowering the resistance. The DPR8EA-9 can be changed to DP8EA-9 plugs. Gets rid of 10k ohms resistance. Then you can open the gap to at least .042 in.

[ThePowster]

Pleased you mentioned plugs Pete, I put in the ones out of the manual which it stated for high speed riding and I remember I never checked the gap of them as I didn't have a tool. I do now so I'll be sure to check that out asap too 👍

Interesting data about the plugs and gap.

[Pete in PA]

I've never used the High speed recommended plugs.  Not necessary.

You risk building up deposits with the colder plug.

[ThePowster]

Update.

I took the Nighthawk round the block today to see if there was a change and holy moly  yep there's a difference alright. So I must have been running on 3 cylinders or something before.

Just need a brake line on it now, too dangerous running on rear brake only lol.

Happy with that 

[coffee_brake]

OP says the bike made a hissing noise after trying to crank. Electrics usually don't hiss, but compression issues might.

[Bob H]

Welcome back Jenn. I remember you from the old forum.
I think you had a late model 750 NH and a VFR? (I still miss my 1986 VFR)

[ThePowster]

Just to add to this chaps and chapesses.

Bike starts and runs a lot better since the coil change. So whether it was ht lead, cap or coils, one of them had failed / was failing.

Right onto my next issue.