Resistor type caps

Hello all, I recently replaced my original ignition coil with an Emgo unit Wich I am really happy with, however I noticed while doing some maintenance that my Ngk caps have 10,000 ohm resistors in them. My spark I felt looks a tad weak, will replacing them with a non resistor cap give me a better spark? I have done the coil mod so am getting all the power to the coil and I'm using standard non resistor plugs. 1977 kawasaki kz750 twin.

I don't use resister, plugs, wires or caps.
Steve

swest wrote: I don't use resister, plugs, wires or caps.
Steve

Same here. Ed

New 750 wrote: Hello all, I recently replaced my original ignition coil with an Emgo unit Wich I am really happy with, however I noticed while doing some maintenance that my Ngk caps have 10,000 ohm resistors in them. My spark I felt looks a tad weak, will replacing them with a non resistor cap give me a better spark? I have done the coil mod so am getting all the power to the coil and I'm using standard non resistor plugs. 1977 kawasaki kz750 twin.

10,000 ohms is likely too high.
The NGK caps listed at Z1E have 5,000 ohm resistors.
Click here > www.z1enterprises.com/store/brand/ngk/ngk-spark-plug-caps

Am pretty that sure NGK also manufactures zero ohm caps.

Good Fortune!

New 750 wrote: Hello all, I recently replaced my original ignition coil with an Emgo unit Wich I am really happy with, however I noticed while doing some maintenance that my Ngk caps have 10,000 ohm resistors in them. My spark I felt looks a tad weak, will replacing them with a non resistor cap give me a better spark? I have done the coil mod so am getting all the power to the coil and I'm using standard non resistor plugs. 1977 kawasaki kz750 twin.

The amount of energy "wasted" by the resistor is microscopic. It basically adds a little "R" in series with the coil's L and C so it will ring less when the points open. If you run resistor caps you don't need resistor plugs or wires. Just run resistor on one is enough. I ran without any resistance for a lot of years. It just puts out a lot of EMI. Your bike has points so it shouldn't matter but CDI systems with Hall effect sensors can be upset by electrical noise.

bountyhunter wrote: . . . The amount of energy "wasted" by the resistor is microscopic. It basically adds a little "R" in series with the coil's L and C so it will ring less when the points open. . . .

the coil's L and C :huh:




Kidding aside, bountyhunter is very knowledgeable about this stuff.

Good Fortune!

New 750 wrote: Hello all, I recently replaced my original ignition coil with an Emgo unit Wich I am really happy with, however I noticed while doing some maintenance that my Ngk caps have 10,000 ohm resistors in them. My spark I felt looks a tad weak, will replacing them with a non resistor cap give me a better spark? I have done the coil mod so am getting all the power to the coil and I'm using standard non resistor plugs. 1977 kawasaki kz750 twin.

Does the Emgo coil have integrated built-in plug wires?
Hopefully not using old hard cracked worn-out voltage-leaking spark plug wires. :pinch:

Has an ohm test been done measuring between ends of plug wires without the NGK caps, and compared with the same test measuring between inside of the NGK plug caps?

Are the above ohm measurements consistent with specs as provided in the FSM?

Good Fortune!

A stock Z1 plastic plug cap may be crushed to find inside a small chunk of what appears to be some form of carbon, which I presumed to be the resistor because there was nothing else besides pieces of broken plastic and the coiled wire that clamps onto the top threads of the spark plug.

Whatever had gone bad inside the stock cap was evidently resulting in weak plug spark, because a replacement cap resulted in a fat blue spark.

Am having very good results -- including healthy fat blue sparks -- using Dyna solid core spark plug wires that come with non-resistor plug caps already built in. And as others have mentioned, am not using any resistance in the secondary circuits (i.e., am using non-resistant plug wires; plus non-resistant plug caps; plus non-resistor spark plugs).

Voltage measured at the coil primary terminal should ideally match battery voltage between the battery posts.





Good Fortune!

Yeah the emgo one has the wires "built in" it looks like there is a dab of epoxy holding them in, I'm sure they could be changed, I have a few feet of 8mm yellow wire I would much rather use, I think the yellow looks cool and it's a little thicker, but I don't wanna risk pulling it out if I'm wrong. I checked it and with the caps off it was in spec per the manual . just a FYI for those looking to replace their coil and can't offord yamaha or dyna, about a year ago I bought one on eBay a Chinese knock off, first one was doa, the seller was good and sent a new one asap and it lasted about a week, only time it left me stranded, so I put the stock one back but the spark has been weak ever since, this current coil I got on amazon for 40.00 and is labeled coilspec, produces a nice fat spark. The mounting holes don't line up as this one is smaller bt that's easy to work around.

New 750 wrote: Yeah the emgo one has the wires "built in" it looks like there is a dab of epoxy holding them in, I'm sure they could be changed, I have a few feet of 8mm yellow wire I would much rather use, I think the yellow looks cool and it's a little thicker, but I don't wanna risk pulling it out if I'm wrong. I checked it and with the caps off it was in spec per the manual.

Where the ohms are in spec, would stick with the built-in plug wires. Main concern was them being new (as they are with the new coils).

I believe the stock plug wires are 7mm. Another difficulty with fitting the 8mm yellow plug wires could be that they are too large to readily fit into the coil recesses unless the wires are trimmed down to fit into the recesses.

As known, there's no performance advantage in using the larger diameter plug wires.

Good Fortune!

New 750 wrote: Hello all, I recently replaced my original ignition coil with an Emgo unit Wich I am really happy with, however I noticed while doing some maintenance that my Ngk caps have 10,000 ohm resistors in them. My spark I felt looks a tad weak, will replacing them with a non resistor cap give me a better spark?.

If it does, it would be because the coil was weak or the condenser bad or something similar. Understand that the coil winding is in series circuit with the plug cap and the air gap of the spark plug. So when the points open, the voltage builds up on the coil winding until it gets high enough to jump the air gap which is probably in the range of 8kV to 12kV ballpark. If there is a 10k resistor in series with an air gap (which has an impedance of many megohms) the voltage drop across the 10k is microscopically small and does not change the voltage that jumps the spark gap, it just means the voltage that the coil winding has is a tiny bit higher when the plug fires. So a resistor cap with 10k Ohms probably won't affect your spark at all assuming the coil is decent. If the coil was so wimpy all it could muster was maybe 10kV max then a resistor cap might degrade performance but that would be a bad coil. Most can do 30+kV open circuit but in use they only go up as high as needed to spark across the plug and that "clamps" the coil voltage at that value so they don't go any higher.

Hope that explains it..