Coils, I think?

[frijoles-and-beans]

I've been thinking about my coils lately. I have my bike parked right now because I'm painting the tank, but before I parked it, I noticed that from first to about third gear there is some misfiring. I suspect that it still misfires in higher gears, but it is just less noticeable.

Well anyway, I have begun to suspect the coils. I've been reading some of the past threads trying to get a better idea of the problem, and I think that's what I've boiled it down to.

I'm at work right now, so I can't test them yet, but I will within the next couple of days. What do you guys think about it? I can hear it and feel it misfiring in first, second and third gear, and like I said earlier; I bet it keeps misfiring all the way up to fifth.

I have seen you guys talking about coil upgrades. Do you think this would be a good idea for my problem? Even before I test it, I think that it's the coils.

[posplayr]

coil upgrade is fine, but also check the voltage to the coils, Generally a coil relay mod is highly recommended

[Jedz123]

If it's misfiring under load? I would check/replace spark plugs. I replace all my plugs in all my bikes every5-7k miles or every year(whatever comes first). My 750 would foul at least 1 plug causing miss fire every 7k miles or so... Plugs are cheaper then coils...

If you just replaced the plugs then disregard my post.
Good luck!

[frijoles-and-beans]

coil upgrade is fine, but also check the voltage to the coils, Generally a coil relay mod is highly recommended

Coil relay mod, ok that sounds like we're going in a good direction there. I will check things out later today and report back. So you're saying that it might not be getting enough juice to the sparks and the relay, of course, would be the fix? I may not even need new coils? If I can get away with just the relay fix, I'll do that for now.

Just from all the hype that I've read here about coil upgrades, it makes me want to upgrade too.

[frijoles-and-beans]

If it's misfiring under load? I would check/replace spark plugs. I replace all my plugs in all my bikes every5-7k miles or every year(whatever comes first). My 750 would foul at least 1 plug causing miss fire every 7k miles or so... Plugs are cheaper then coils...

If you just replaced the plugs then disregard my post.
Good luck!

Thanks for the post Jedz. I have new plugs in it. Less than 300 miles on them. The engine seems to treat my plugs with the utmost care. Every time I replace them, they are immaculate. I guess it helps that I change them every 1,500 miles.*I could leave them in for a while, but this is my only bike and I'm gonna take care of it.*

For the past few months, I've been eyeballing that coil set-up and meaning to check on it. I guess that it's time to do it.

[rustybronco]

The engine seems to treat my plugs with the utmost care. Every time I replace them, they are immaculate. I guess it helps that I change them every 1,500 miles.*I could leave them in for a while, but this is my only bike and I'm gonna take care of it.*

Then can I have your old worn out ones there's no sense in me spending 'my' hard earned money if I can get some perfecty good ones that I can use for say the next 12~15,000 miles.

Beans, measure the voltage at the coils along with the coils primary and secondary resistances, then you should have a good idea if you need new coils or not.

[frijoles-and-beans]

Then can I have your old worn out ones there's no sense in me spending 'my' hard earned money if I can get some perfecty good ones that I can use for say the next 12~15,000 miles.

Beans, measure the voltage at the coils along with the coils primary and secondary resistances, then you should have a good idea if you need new coils or not.

I knew somebody was going to say it. That's why I put in the edit. haha.

Thanks for the advice. I'll check them tonight.

[rustybronco]

The best advice I can give you comes from Ed... "to measure is to know".

it's good sound advice.

[frijoles-and-beans]

Here's another thought. Although I have yet to confirm it, I bet that the numbers will be well within specs tonight when I check said coils. That's actually why I was originally talking about not even just replacing them, but upgrading as well. I figured the coils for a lost cause. posplayer's made me think twice now about replacing or upgrading if his fix is what the doctor ordered.

This is just thinking out loud, as I have yet to check anything right now. Update later.

[koolaid_kid]

f&b, a coil is nothing more than a voltage multiplier. The more windings, the higher the multiplication factor. That is why the aftermarket coils are larger, they have more windings. Let's say my Accel coils output 35,000 volts at an input voltage of 14 volts. That is a multiplication factor of 2500. However, let's say my input voltage is only 11 volts. That yields an output voltage of only 27600 volts, a significant drop. That is why you want to maximize your input voltage prior to changing the coils.
Hope this makes sense.

[salty_monk]

You may want to check the plug wires. I'd be more inclined to believe that the wire insulation has degraded & you are getting sparks grounding to the head than that a coil is faulty but it can happen....

To check if your wires are "leaking" run the bike at night in a really dark place (I used a garage with the door shut). You can see the sparks then! You may need to move the wires around a bit to make it happen - I would use something non conductive to do so!

Check voltage & relay mod is good as described above.

If all the above checks out then you might also want to look at your ignitor... that's another source of missfires, RPM ceilings & general bad running (not necessarily all together.. I had a 1000G that ran great until it hit an "RPM ceiling" at 6,000 - ignitor was bad).

[frijoles-and-beans]

f&b, a coil is nothing more than a voltage multiplier. The more windings, the higher the multiplication factor. That is why the aftermarket coils are larger, they have more windings. Let's say my Accel coils output 35,000 volts at an input voltage of 14 volts. That is a multiplication factor of 2500. However, let's say my input voltage is only 11 volts. That yields an output voltage of only 27600 volts, a significant drop. That is why you want to maximize your input voltage prior to changing the coils.
Hope this makes sense.

Oh, I like your explanation; very straightforward. Ok, so maybe I want to do the relay AND upgrade the coils, and I'll get that nasty misfiring out of my life forever in the process. It really bugs me.

You say that the aftermarket product has a higher voltage output? Ok, so the relay will amplify the voltage going to the coils, and the coils will then amplify it once again to a specified voltage in the new higher output "upgraded" coils. Hmm, that sounds like a good deal. There you go, I think you have me sold on the idea of just changing the dang thing out and not even worrying about the current coils.

posplayer, I just noticed that you're the one who wrote the relay mod on Cliff's site. Very useful information that'll be for me. What type of relay should I ask for? It says automotive, but what kind?

[frijoles-and-beans]

You may want to check the plug wires. I'd be more inclined to believe that the wire insulation has degraded & you are getting sparks grounding to the head than that a coil is faulty but it can happen....

To check if your wires are "leaking" run the bike at night in a really dark place (I used a garage with the door shut). You can see the sparks then! You may need to move the wires around a bit to make it happen - I would use something non conductive to do so!

Check voltage & relay mod is good as described above.

If all the above checks out then you might also want to look at your ignitor... that's another source of missfires, RPM ceilings & general bad running (not necessarily all together.. I had a 1000G that ran great until it hit an "RPM ceiling" at 6,000 - ignitor was bad).

Ok, so that's a lot more to check. Maybe I should just take this slowly and eliminate some possibilities first.

[frijoles-and-beans]

Holy shyte! I just checked the price of a new Dyna 2000 Ignition for mine. I hope it's not that!

[1948man]

Don't be in a hurry to replace your coils and when you measure the resistance, it might be 8 or 10K low if you have aftermarket plug caps. On my 1100Gl, the OEM caps had about 11K ohms resistance each. If you have newer caps with only 5K ohms, it will make your cap to cap resistance seem low. A quick test is to turn your key on and check the voltage at your battery. Then check the voltage at the positive prong on a coil. There shouldn't be much difference, maybe half a volt. If you're only getting 10 or 11 volts to the coil, the relay mod is a great idea.