Another coil problem

korvette kid · Post by **korvette kid** » Wed Apr 02, 2008 8:42 pm

Greetings all. I am a new member with a 1982 that i have owned since new, I decided to install a new set of accell coils and find that only number 3 and 4 cylinders are working. Prior to this the bike operated normally. I have checked all the wiring, switched new plugs to 3 and 4 and got a spark. I then switched wires to see if my crimping was at fault and they all worked on 3 and 4. I have the 4 prong power connection and noticed that ther is a union on the feed wires to the center coil that shares a connection to the third coil (cylinder 2 and 5) yet it will not fire either.
With everything working normally prior to the new install, could there be two bad coils?
Any help or direction to a tech article would be greatly appreciated.

thanks

CBXRoger · Post by **CBXRoger** » Thu Apr 03, 2008 1:00 am

Try swapping one of the old coils in place of one not working. See if you have spark now.

Juha · Post by **Juha** » Thu Apr 03, 2008 6:02 am

Hello!

Do you have a multimeter?

The weak point in Accel coils is the primary side connectors (where you connect the ground and +12V leads).

If you look at the tip of the terminal thread you can see there is solder, this solder breaks easily when the lead is tightened to the terminal. Easily fixed with a solder gun.

Disconnect the primary side wires and check the resistance between the terminals, should be around 3 ohms. Better if you can check the resistance from the previous connection before the coils, so that the leads are connected to the coils and the measurement is made from the previous connection point. This will tell more accurately what is the situation in the "assembled condition", terminals tightened.

Hope this helps,
Juha

alimey4u2 · Post by **alimey4u2** » Thu Apr 03, 2008 7:04 am

To add to the excellent advice of prior posters, battery condition ?? A wild card I know but a simple fix.

EMS · Post by **EMS** » Thu Apr 03, 2008 7:20 am

I bought a set of Accel coils brand new a couple of years ago and one was bad. Measuring the coils for resistance is easy with a multimeter and tells whether they are bad. I wouldn't be surprised.

EMS · Post by **EMS** » Thu Apr 03, 2008 7:22 am

Juha wrote:Hello!

Do you have a multimeter?

The weak point in Accel coils is the primary side connectors (where you connect the ground and +12V leads).

If you look at the tip of the terminal thread you can see there is solder, this solder breaks easily when the lead is tightened to the terminal. Easily fixed with a solder gun.

Disconnect the primary side wires and check the resistance between the terminals, should be around 3 ohms. Better if you can check the resistance from the previous connection before the coils, so that the leads are connected to the coils and the measurement is made from the previous connection point. This will tell more accurately what is the situation in the "assembled condition", terminals tightened.

Hope this helps,
Juha

...and welcome Juha! So good to hear from you again!
Guys: Juha owns one of these rare black 1979 CBXes

Louis · Post by **Louis** » Thu Apr 03, 2008 8:04 pm

Mike, I also have one of those rare black 79 euro CBXs

EMS · Post by **EMS** » Fri Apr 04, 2008 7:11 am

Only you didn't buy it new and don't really know for sure (maybe you do

) if the bodywork was changed...What is the manufacturing date on the VIN-plate??

Juha · Post by **Juha** » Fri Apr 04, 2008 9:03 am

EMS wrote: Guys: Juha owns one of these rare black 1979 CBXes

...right.

Black it is, don't know who and where made it black but I'm going to make it even more black -- will paint the engine black too

Back to the subject, if you have a dead Accel coil, this is where you should look before throwing it away.

There is a lead inside the hollow threaded outer part, this soldering connects the two. And this soldering is fragile

A friend of mine installed new Accels on his 1100F and managed to break this solder when he worked the nut over the tip, the solder work was a bit sloppy and was in the way

The engine ran with two cylinders only and my friend was confused. Finally he checked this point and bingo, just melting the original solder material a bit cured the problem.

alimey4u2 · Post by **alimey4u2** » Fri Apr 04, 2008 9:23 am

Excellent support Juha.....

EMS · Post by **EMS** » Fri Apr 04, 2008 9:32 am

Juha wrote:
EMS wrote: Guys: Juha owns one of these rare black 1979 CBXes
...right. Black it is, don't know who and where made it black but I'm going to make it even more black -- will paint the engine black too

.

Some countries in Europe, Germany was one, never had the SC03-1980 CBX. Instead, Honda kept selling the CB1 model with black bodywork.
That is the reason for the black "1979". All original black 79s should be late VIN-number 79s. Remember, the SC03 was build in Japan and in the U.S. Maybe the transfer caused a shortage and Honda decided to not send SC03s to certain parts of the world.

Louis · Post by **Louis** » Fri Apr 04, 2008 5:20 pm

Mike, Email me when you get a chance and I will give it to you. I have to move the bikes around to get to it. Louis

korvette kid · Post by **korvette kid** » Sat Apr 05, 2008 11:34 am

Thanks all for the coil tips. I am on the road for my job, but will employ these ideas when I get home and will post my results. I am curious as to the correct procedure to check the coil continuity. Any help is greatly appreciated. I will have a new mulitimeter when I return home..

thanks for the great info.

alimey4u2 · Post by **alimey4u2** » Sat Apr 05, 2008 3:53 pm

A "very" simplistic schematic diagram of the coil setup.... Note that one pulse from the spark unit fires two plugs, one will be on the power stroke & the other on the exhaust stroke.

Juha · Post by **Juha** » Mon Apr 07, 2008 6:26 am

I was at the garage last night and took a couple of pics.

Here's how you check the primary resistance:

3.4 ohms is a bit on the high side for a stated 3.0 ohm coil but it should work OK, at least it's not broken

Checking the primary resistance from the 4-pin connector:

It shows 2.8 ohms for a stock CBX coil. Same measurement from the coil terminals:

Ouch 0.3 ohms less resistance, maybe cleaning the connectors would be a good idea

The 4-pin connector has one common lead, that is split with the jumper leads at the coil terminals for all the coils. You measure the other three against it. In my case the common lead is the one on the left (see different markings on each wire). I would imagine this is the same in all CBXs.

Then you can also check the resistance between the secondary terminals, this shows 11 650 ohms (11.65 kOhm). If the resistance is infinite, the secondary winding is broken

And finally you can check if there is conductivity between the primary and secondary terminals -- there shouldn't be, this reading on my multimeter means infinite resistance. The auto-range function in my meter is on MOhm (mega-Ohm) range and it still can't find any conductivity. This is the same as keeping the measuring leads separate in air. If there is zero or little resistance here, the coil is in internal shortcut and you get 12V in the spark plug instead of 30.000V or so as you should

As seen from my measurements, I got 2.5 ohms for the stock CBX coil and 3.4 ohms for the Accel. This means less current in the circuit, easier life for the igniter units but in theory a weaker spark -- but I think the more efficient windings on Accel coils should compensate that.

But there are rumours that some of these Accels measure 4.0-4.5 ohms, I think this is too much for our ignition system. If your coils measure 4.5 on the primary, I would try to contact the seller and ask if they could be returned and swapped for ones with primary resistance more in the desired range, I'd say 2.5 to 3.5 ohms.

See more here: http://accel.zn1300.com/

The International CBX Owners Association

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