Strange Problem With Dyna Coils - Any Ideas?

[Blackseven]

I'd be very grateful for any opinions on this - it has got me stumped.

I have a Z1000A1 which has been fitted with Dyna ignition, standard coils and B8ES plugs gapped to 30 thou. The bike has run great like this for the last couple of years.

Whilst the coils worked fine, they were probably original and looked pretty rough, so I decided to fit a pair of used 3 ohm green Dyna coils and Taylor leads.

The bike fired up fine but almost immediately went onto 2 cylinders. 1&4 weren't firing but the coil connections all tested OK and a HT tester showed a healthy spark.

Eventually I fitted a manky old pair of plugs from the bottom of my parts drawer into 1&4 and the bike ran perfect. I took it out for half an hour and it ran perfectly the whole time.

As soon as I re-fitted the original two plugs again (which have run fine for 1000+ miles) the bike was missing and backfiring.

The only difference between the first and second pair of plugs was the gap, the second pair were set to 25 thou. I re-gapped the originals to 25 thou and it was better but still very rough.

So, it seems like one of the Dyna coils has mysteriously damaged both of the plugs it feeds within the first few seconds of use but then started working perfectly.

I can't work out why this is, and now have doubts about the Dyna coil. Can anyone offer any help with what might have gone on here?
Thanks,
Rob

[KeithZ1R]

Resistor plugs with resistor Plug caps possibly general consensus is one or the other, but not both

[Blackseven]

Non resistor plugs NGK B8ES and Taylor leads which I think are also non resistor.

I which case Rob its swap around and substitution until you come across whatever is causing the issue but start with how you have fitted the Dyna's. They are a good product but their physical size requires some thought during mounting electrickery will always find the path of least resistance

[kev edwards]

Put your old coils back on and try both sets of plugs if it's running fine on them, it will be the dynas or new leads, have you insulated around the dyna mounts close to where wires attach as they are notorious for arcing to earth, they are also known for cracking, had a pair on one of mine and they cracked, expensive rubbish, I use coils from z-power, a lot cheaper and do the same job.

[chrisNI]

Put your old coils back on and try both sets of plugs if it's running fine on them, it will be the dynas or new leads, have you insulated around the dyna mounts close to where wires attach as they are notorious for arcing to earth, they are also known for cracking, had a pair on one of mine and they cracked, expensive rubbish, I use coils from z-power, a lot cheaper and do the same job.

The arcing issue is because the screw that holds one on the wires on is somewhat close to one of the mounts on a Zed, it’s pretty obvious and just needs a bit of insulating tape round the mount. I’ve had a pair on my Z1000 since the mid nineties with no issues so far.

[kev edwards]

Put your old coils back on and try both sets of plugs if it's running fine on them, it will be the dynas or new leads, have you insulated around the dyna mounts close to where wires attach as they are notorious for arcing to earth, they are also known for cracking, had a pair on one of mine and they cracked, expensive rubbish, I use coils from z-power, a lot cheaper and do the same job.

The arcing issue is because the screw that holds one on the wires on is somewhat close to one of the mounts on a Zed, it’s pretty obvious and just needs a bit of insulating tape round the mount. I’ve had a pair on my Z1000 since the mid nineties with no issues so far.

Had them insulated, the coils still split and cracked and mounted properly longer spacers, wouldn't buy them again, i have the dyna ignition though.

[zed1015]

You problem sounds a bit random and likely a one off and was possibly down to an iffy coil connection especially if you can't repeat the issue.

One thing to watch with the Dyna coils is that you need longer mounting spacers.
With the stock ones the coil body hits the frame and when the bolts are tightened the steel core bends which eventually leads to the cracked insulation many complain about.

[ADRIAN H]

If you leave the key turned on DYNA coils can burn out, unless kill switch is turned off.

[Blackseven]

Thanks everyone for your thoughts and advice.

The Dyna's have been carefully installed using 25mm long nylon tubular spacers to give the correct stand off from the frame and overcome the shorting risk with the tight fitting low tension connection. I've removed the powdercoat from the underside of the Frame bracket to give a clean earth connection via the mounting bolts. All resistances check out.

Today I swapped the 1-4 coil with the original Kawa one - it is exactly the same with the original two plugs which now appear to be knackered.

The only thing that I've found that was possibly suspect was that one of the HT connections wasn't pushed fully home into the coil - difficult to see with the tight fitting boot and limited space.

Anyhow, I've ordered some Denso's instead of the NGK's and will put some miles on it next week to test out further.

[z1bman]

be careful when buying spark plugs online
http://www.ngk-sparkplugs.jp/english/te ... index.html

https://www.youtube.com/watch?v=7fyD1BXnhtY

[Blackseven]

Thanks however the NGK's that failed came from a reputable source and have been perfect for well over 1000 miles so are almost certainly genuine.

I view most NGK's on Ebay with suspicion and have new Denso's on order from www.sparkplugs.co.uk

[Big Fluff]

Agree with the guys, standard Dyna coils are a pain in the ass. Their mounting design is shit, they often crack and arc out.
If you want Dyna coils then fit the mini Dyna coils. I've fitted these to the last four Z1R-TC's I've built without any problems and there's loads of room left.

[Blackseven]

Thanks for all the advice. With new Denso plugs fitted its running better than ever. The only explanation for the failed plug I can think of is that the old NGK was on its way out and the increase in voltage from the new Dyna coils finished it off.

As for why so many people have had problems with cracking on Dyna coils, I think zed1015 is spot on with his comment above. With 20mm spacer tubes, the coils tighten down and look like they are clear of the frame but one of the moulded lugs on the coil body is actually in contact with the frame but it is very difficult to see. With 25mm spacers tubes there is no contact.