Quick spark check, ground coil?

[Macmatic]

Is it safe for the coil to quickly ground it as a means of testing spark? I've just done the coil mod but the spark seems worse than before. I double checked connections yesterday and will triple check today.... I have 12v+ from battery going to 30, coils connected to 87 and 87a, ground on 85 (grounded to R/R, ignitor bracket which is grounded to battery by the extra R/R ground) and O/W wire from one of the coils attached to 86. This is from memory... maybe 85 and 86 are the other way around.

[edit] I just tried the existing relay and a new out of the box relay, 87 and 87a both have power when the ignition is on, none when its off. Still no solid spark[/edit]

But, main question: Can I hook up 12+ to one side of a coil and touch ground to the - side quickly to test spark? I suspect I have a bad/dirty relay since its used and been in the garage for a few years and voltages to the relay checked out before I called it a night last night.

Thanks,
/\/\ac

 

[Ed Vrolijk]

This is something i picked up from a site (dont remember wich) So the way you connected the coils, (on 87 and 87a) is wrong'
Hope this helps.
Ed

Connections

The terminals of a relay are defined as follows:

• 30 is the common or input voltage (or ground) to be switched.
• 87a is the normally closed connection (can be used as a switched voltage output when the relay is at rest). (This terminal offers no voltage when the relay is energized.)
• 87 is the normally open connection (switched voltage output when the relay is energized).
• 85 is connected to the ground of the triggering voltage.
• 86 is connected to the positive 12V of the triggering voltage.

Note: in many cases, the connection of pins 85 and 86 can be interchangeable, but NOT if there is a diode wired across the coil. Below are several common examples of how relays are commonly used:

 

[Macmatic]

This is something i picked up from a site (dont remember wich) So the way you connected the coils, (on 87 and 87a) is wrong'
Hope this helps.
Ed

Connections

The terminals of a relay are defined as follows:

• 30 is the common or input voltage (or ground) to be switched.
• 87a is the normally closed connection (can be used as a switched voltage output when the relay is at rest). (This terminal offers no voltage when the relay is energized.)
• 87 is the normally open connection (switched voltage output when the relay is energized).
• 85 is connected to the ground of the triggering voltage.
• 86 is connected to the positive 12V of the triggering voltage.

Note: in many cases, the connection of pins 85 and 86 can be interchangeable, but NOT if there is a diode wired across the coil. Below are several common examples of how relays are commonly used:

huh. Thanks! I must have read the diagram on the relay wrong, it looked like 87 and 87a were both hot when the coil was energized. I did have spark at all four plugs but it was weak and hard to see in the garage.

/\/\ac

 

[Macmatic]

This should work, right? Put a plug in the plug cap, hook 12+ up to the + terminal on a coil, hook a wire up to the - terminal and then quickly touch ground and you should get a nice fat spark from the plug?... right? Does the coil need to be mounted to the frame?

'cause I got nothin.

Coil is well within spec across the low side and the HT side, 3.2ohm on the low and I can't remember the HT side from last night but it was good. I'm getting nothing at all this way. I'll try another coil but I want to make sure I'm not roasting my coils first. I can't see how this would really be any different to the coil (other than pulse period) than normal operation.

/\/\ac

 

[Ed Vrolijk]

I really don't know if you can test a coil in the way you described.
I hope sombody else can help you on this.
succes,
Ed

 

[Macmatic]

Ed,

I made up a test rig with a 12v battery , fused 12v lead and some ground leads. I hooked up the coil to +12v and ground to the battery and also ground between the battery and plug body. I did get spark this way but it was weak just like on the bike. What I hadn't realized at the time was that I needed to have BOTH plugs on the coil grounded to get good spark. I'll try this again tonight with both plugs grounded to the battery and we'll see what we get.

I was thinking that the one grounded plug would get a full shot from the coil.

This is why I stick to the wrenches....

/\/\ac

 

[Ed Vrolijk]

Like i said Mac, i don't know that much about coils. I know about relays though, but the ones i work with are a bit heavyer (400 V 60 A)
I think you have to be carefull with your test rig, because in this way you are actually short circuiting the battery. Don't leave the power on to long, and keep checking that the wires to and from the battery don't get to warm
Good luck with your testing, and i do really hope sombody who knows more about ignitions and coils reacts to this thread.
Ed

 

[don_gibb6512]

Is there any detriment to connecting the 85 ground wire from the relay to one of the coil mounting bolts on the frame? That's a lot closer than any other good source for ground on my bike.

- "not an electrical engineer" -

Don