1978 kz750 twin

IM NEW TO THIS... SO BARE WITH ME PLEASE
Q; HOW DO YOU TEST THE COILS AND WHERE DO I HOOK MY OHM METER TO THEM?
ALSO.. WHAT SHOULD IT READ... ITS A DUAL COIL SYSTEM?
ANY HELP WOULD BE GREAT.
THANKS GREG

It is a single coil, 12V type with no external ballast resistor. You should read close to 12V on the terminal coming from the ignition key.

There honestly is no way to accurately test a coil. The primary side should read about four Ohms resistance. I think the secondary is maybe 10k or that ballpark?

However, most old coils are bad because they are failing due to a high voltage "arc" internally and there is no way to test this.

Z1 sells an EMGO four Ohm coil for $36 that will work. I am running one and it is hotter than the stock coil (bike starts easier).

whats the website for z1?

INDYIRONS wrote:

whats the website for z1?

Hello, Greg, and WELCOME to KZr!
We're glad you're here!

For Z1E website, click > www.z1enterprises.com/

Good Fortune!

Ignition coils fail for several reasons, two I can think of are:

1.Lack of cooling air; where they are mounted under the gas tank traps the heat from the engine and the only cooling is when the bike is moving.

2.Vibration; the coils are not isolated from the many various frequencies and amplitude of vibrations.Over time and heat the internal insulation will fail.

Hi Greg,I ordered the coil that's been suggested and it hasn't arrived yet. On my particular bike the mounting points say they are about 90mm and my stock is 100mm. No biggie as I acquired a metric tap to remount if in fact the coil is a different mounting distance.

I had a single coil from a honda and the spark was very weak. What made my mind light up was checking a chain saw I was rebuilding the spark on that was bright and made a crispy sound where the KZ needed the door closed and was intermittent. I don't think I went wrong ordering a new coil and points setup. Fresh is fresh and my old basketcase needs as much help as it can get.

Still embarrassed to post pics.

Jeff

hey guys, im tearing apart my KZ trying to get her to spark. thinking its the coil too.

where did you find the coil for sub $40...?

anything else to look at? anything in the ignition that is known to fail?

thanks guys!

Truc wrote: hey guys, im tearing apart my KZ trying to get her to spark. thinking its the coil too. where did you find the coil for sub $40...? anything else to look at? anything in the ignition that is known to fail? thanks guys!

A defective coil is only one of several possible reasons for failed spark.

Has the coil been ohm-tested?

Good Fortune!

Truc wrote: hey guys, im tearing apart my KZ trying to get her to spark. thinking its the coil too.

where did you find the coil for sub $40...?

It is the 4 Ohm Emgo coil that sells for $36. I can't post a link because the Z1 server is stone dead, won't open from any of my three browsers. They really need to fix that thing it is beyond annoying.

I just asked the smae questions about a week ago, it should all be in my "ignition questions" thread. basically all together should be around 2omh for a points ignition, which my 78 750 twin came with.

when i bought my bike it had a 4cyl coil on it.

I ended up buying an dynatek electronic ignition which required a higher resistance coil. I bought a 4 ohm coil to compensate for the resistance.

as long as your coil(or coils, if single output) is between 2-4ohms you should be fine. But if you have a 4ohm coil you may have problems with weak spark due to high resistance.

see patton and bounty hunter, i listened. :lol:

Here is the 4 Ohm coil which is the functional replacement for stock 750 twin coil with points ignition. It is definitely a single coil system. All of the 750 twins from '76 - '79 used 4 Ohm coil/points ignition. I think some of the 400 or 440 twins had electronic ignition, not sure what years.

This coil is for any points system:

www.z1enterprises.com/ItemDetails.aspx?i...zuki&item=EM24-72451

The bikes with electronic ignition use a lower resistance coil (like 2.2 - 3 Ohm range). You can use the 4 Ohm coil with electronic ignition but it may put out a bit less energy, not sure if you will notice any difference.

Patton wrote: A defective coil is only one of several possible reasons for failed spark.

Has the coil been ohm-tested?

Good Fortune!

yeah, finally. its done. no continuity between sparkplug wires.

on the hunt for one before buying a new one