Topic: Before installing CB900 Coils?

[DrMark]

Got lucky on EBAY today....won a set of CB900 coils for $10, including brackets, wires and caps. Now, here is my question, before installing them on my 1978 CB550...what else should be done? Somewhere in archives, I read that the plug gaps should be widened from 24 to 35. Is this true? I know many of you swear by these coils.....what other problems have you not talked about? Thanks, Dr. Mark

[eldar]

I would like to know about this as well since I am going to get these coils. I think gap can be opened up some though. I would go to 30 probably.

[SteveD CB500F]

Someone out there done this ??

Write it up here and I'll put it in the FAQs

Steve

[cub]

Not done yet, but I got CB650 coils (the same as for 750/900) to put on my CB500 bike. I noticed that I need to fabricate new mount since they didn't bolt right on. The new coils have the mounts turned 90 degrees...

[andy750]

Hi I have the CB900 coils on one of my CB750K4s and never widened the spark plug gap. I do use resistor caps on the plugs as Im using automotive wires (gray) but apart from this Ive done nothing else. I run NGKD8 EA plugs straight out the packet with no problems (have done this in a "road test" for 25,000 miles (in last 4 years).
Hope this helps,
Andy in Boston

[DrMark]

Are the original wires and caps on the CB900 coils the resistor type?

[andy750]

I dont think so. I have another set of CB900coils and the wires and NGK caps look the same as the CB750 so most likely non-resistor. On the running bike I changed the original wires for coloured auto ones from local auto store (PepBoys).
Hope this helps,
Andy in Boston

[DrMark]

How do I tell the difference between the 2 types of caps? What model number should I look for at NGK?

[eldar]

Well I have not found non-resistor caps yet BUT with the ngk caps, you are supposed to be able to unscrew a small part INSIDE the PLUG end of the cap and pull out the resistor then replace it with a copper piece. The wires though should also be NON resistor.

[DrMark]

OK...I should be using resistor caps or resistor-type wires...but not both together? Is this true? Eldar's comments have me confused.

[Robert]

>>>OK...I should be using resistor caps or resistor-type wires...but not both together? Is this true?

Yup. Or you can use non resistor caps, non resostor wires and go for resistor plugs, AFAIK the iridium plugs (which I dig btw) only come with resistance.

Again, I'd suggest to use one 5 kOhm resistance. While this will make the spark seemingly "weaker" (spark will glow brighter without any additional resistance in the secondary ignition circuit if you compare it with the spark that is produced WHEN using a resistance) using a 5 kOhm resistance has the benefit of making the spark burn longer which helps to burn the mixture better. (+ noise suppression 'for free'  )

There was a more indepth explanation here written by twotired.

Also I'd suggest to take care that the ignition coils primary resistance (CB 900 coils:   2.1 Ohms) match the ignitions system used (points, pickups or whatever you use) propably another story.

[eldar]

It is simple. Our bikes came with NON resistor wires and RESISTOR caps. The NEW ngk caps can be MADE NON resistor. You do not need resistors on either part unless you have electrical equipment or maybe electronic ignition. Thus with the 900 coils, you will use NON-resistor wire and plug caps depends on your ignition. I use points so when I get my 900 coils, I will go non resistor all through unless I run into issues, THEN I will use resistor CAPS.

[DrMark]

Good news and Bad news. Received my new coils last night....a bit dirty...excited to get them installed. I started cleaning them up and noticed a large crack in the housing for the 1-4 coil. EBAY seller was kind enough to refund my purchase price this afternoon.

Does anyone have a set of coils (with changeable wires) I can use for a 1978 CB550? I'll be using a Dyna-S DS1-2 Electronic Ignition.

Santa sent a broken present....lololol