Change to Coil over plug

[Choter]

I was going to do this so that I can install the R&G crash sliders without having to relocate the factory coils, the only problem I am seeming to see is that the factory coils primary resistance is 2.1 ~ 2.5Ohms and every coil over plug I find is from 1.1-1.8 ohms some even lower all of the secondary resistances are the same though. Will this burn out my ECU or not work properly from them being lower ohm? Even the EUR spec version of our bike that comes with coil over plug factory, they have lower resistance but I'm sure the igniter/ecu is different too. If it will cause damage does anyone know how i can find COP within the proper primary resistances? Thanks for any help.

[HKr1]

Might just cause a problem to the flakey stock cdi's. Maybe worth a shot thou, if you have a set sitting around

I know other folks have done the mod. But, they were 4 cyclinder bikes. They also never mentioned how they wired them up.... figure they probably went in series. Being stock was two coils, and the mod went to 4. that would keep the resistance in the ball park for them.

[wyckedflesh]

There is a DIY on Miata.net that explains how someone wired a coilpak Miata setup to CoP and which resisters he needed to use for the CoP's to be happy.

[HKr1]

Any resistance you add, would just cut down the overall spark output. Which really makes me wonder how those guys went from 2 to 4 coils and use the stock cdi......

Anyway, maybe just relocate the stock coils. And run some better spark plug wires.

[Choter]

They run 2 coil over plugs off each lead in series(adds the resistance) so the load on the ECU is exactly the same. If you go lower resistance you can make the ECU burn out if it cannot keep up with the higher amp draw without overheating.So it works perfect for them because each 2 coil over plugs series together =exact same ohms as their previous one coil pack that fed 2 plug wires. Thats where the problem with the ninja 250 comes(ninja 500 is the exact same coils and setup also) in we have 2 coil packs and only 2 plugs and our coil packs have a resistance of 2.1-2.5 ohms so we have to use like one coil over plug which is .3 ohms to like 1.8 ohms depending on what bikes you use then we have to add a resistor inline to increase the ohms to that 2.1-2.5 target range. The output on the coils does not change, thats the secondary coil(the one to the plug) it is just a matter of matching the primary ohm(going into the coil over plug) so we dont overheat our ignitor/ecu. So it looks like I will just end up using zx6 coil over plugs(zx6/10 and the 650r all use same part number) and wiring a resistor up. Removing the 2 coil blocks from factory will equal about the same weight the sliders add in addition to making the mounting for them work.

[kkim]

seems like a lot of work and a real potential for a major problem if you don't get everything just right... all for some sliders?

have you considered using a different set of sliders that doesn't require such modifications... or, heaven forbid, no sliders at all?

[GiGs]

I'm really not sure if this will help you but I came across a product (while I was looking to throw more money at my bike ) called Nology Hotwires ... from some real quick skimming they increase spark. Not sure if they are different size etc, maybe something to look into - on a side note also consider what kkim was suggesting

[wyckedflesh]

Originally Posted by GiGs

I'm really not sure if this will help you but I came across a product (while I was looking to throw more money at my bike ) called Nology Hotwires ... from some real quick skimming they increase spark. Not sure if they are different size etc, maybe something to look into - on a side note also consider what kkim was suggesting

Hotwires are not snake oil, but, for the price, the gain is minimal and still does not help here.

There is nothing that says the 2nd coil over plug has to "fire" on a plug. You can ground it in series so that when it does fire, it just grounds out without interefering with the active CoP. It is a common trick when using Dual Fire coils in single fire operations. So in effect you would have 4 CoPs, wired in series 1L2g3L4g so that 1 and 3 are on the plugs, with 2 and 4 grounded to the motor.