Honda CB77 Ignition Coil Specs

adriansani · Post by **adriansani** » Fri Feb 03, 2017 2:01 am

hello guys,

anyone know the factory specs for CB77 Coil..?

- ohm size : ...?
- volt spark that it can produce : 30K volts...?

please advice.

Adrian

Tim Allman · Post by **Tim Allman** » Fri Feb 03, 2017 10:46 am

I just had a look in the shop manual and it is, as far as I can see, silent on the matter. However, there is nothing unusual about these coils so a primary resistance (between the terminals) of about 1 or 1 ohms and a secondary resistance of 10,000 - 15,000 (between positive terminal and high voltage connector) would be about right. There should be no connection between any terminal and the can.

It takes about 10,000 volts to bridge an air gap of 1 cm and the system should do that easily when functioning correctly with a charged battery.

My experience (mostly cars) is that it is unusual for a coil to fail so if you are having problems it would be best to check out the capacitor, points and wiring before deciding that the coil is at fault.

I hope this helps.

Seadog · Post by **Seadog** » Fri Feb 03, 2017 1:09 pm

This is what I bought from 4 into 1 when I replaced mine:

http://4into1.com/universal-12v-single- ... cb72-cb77/

They seem to out of stock at the moment, but they're made by Emgo and available elsewhere. I can get you the Emgo part number if you're interested.

adriansani · Post by **adriansani** » Fri Feb 03, 2017 4:48 pm

@Tim, Thank u very much. I plan to test my coil today. just got the DIY on youtube, hope everything oke, and will share the result soon.

@seadog, thank u very much for the info .will check it out.

adriansani · Post by **adriansani** » Fri Feb 03, 2017 9:37 pm

Here is my coil measurement. I think it's quite low compare to DIY on YouTube

Multimeter :
- Primary set on 200 ohm (P)
- Secondary on 20K ohm (S)

Right :
- P : 0.42
- S : 8.54

Left :
- P : 0.41
- S : 7.81

Coil cable looks bad. I think need to change them.

Tim Allman · Post by **Tim Allman** » Sat Feb 04, 2017 9:35 am

I just checked a pair of working coils. Your secondary values are close to mine but I get 3.8 ohms for the primaries. Is it possible that your measurement is a factor of 10 out?

adriansani · Post by **adriansani** » Tue Feb 07, 2017 3:06 am

Tim Allman wrote:I just checked a pair of working coils. Your secondary values are close to mine but I get 3.8 ohms for the primaries. Is it possible that your measurement is a factor of 10 out?

Yes sorry. It should be 4.2 and 4.1.

So do you think this measurement is normal and coil still oke ?