XS11 electrical upgrade question

[Boneswig]

Being in South Africa, chicken teeth are more accessible than XS parts and spares. Buying a secondhand part over here is risky so we usually try to upgrade the system to be able to keep her running. About a month ago I did a VW Golf module conversion on a XS. She purred like a kitten and I decided that I will be doing the same on my bobber project by replacing the CDI with modules. Question now is what coils can I use (since I don't have coils on my project). I am considering using GY6 ignition coils (4 of them) and working my way up from there but now last night I read about module heat vs sparkplug heat vs coil resistance and ballast resistance. So need to run the spec's by you clever guys and see if my calculations are correct. Golf modules need a coil resistance of 3ohms on primary coil. GY6 coils in good condition varies between 3 and 4.8 ohms on primary. So using the GY6 coils seems to be the correct route. The sparks plugs (ngk BP6ES) according to the hotwire website needs to be set to 0.5mm to be able to run at the correct temperature. So my question is, will this upgrade work?

[crazy steve]

Does the Golf module support four coils? Or could it only use two?

If the latter, connecting two coils in parallel will give a resistance of less than the lower of the two, in this case a bit more than half of the lowest. So the module will see a load of a bit less than double the normal load.

[Boneswig]

Golf module supports one coil, but I see what you are saying. If I connect two coils per module running positive from one and trigger from other and joining them inbetween (i.o.w in series) ill be doubling the primary ohm rating so I can use any coil I want to. Didn't think of that, thanks for the input.

[crazy steve]

If you run the coils in series, that will lower the current but halve the voltage across each coil. Will those coils put out enough spark at only six volts?

You'd probably be better off to find coils with a 6 ohm primary and run them in parallel.

Another thing to think about is many modern ignitions use something called 'dwell control'; basically varying the 'on' time of the coils according to engine speed. Using a 'dwell control' type coil on a non-controlled ignition will cause coil failure.

[Boneswig]

Ok see what you are saying. No, coils won't run on 6v. Unless I build a relay unit. Module triggers the relay and the relay then supply the coils with 12v. Then I can build a 3 ohm resistor before the relay unit. Then i'll be drawing power directly from my battery pack instead of thru the ignition. I am just waiting for info on a specific voltage regulator and if the regulator can take the punch, I can connect and I'll have 12v 40Ah if the regulator can take the punch.

[crazy steve]

The XS alternator will only put out 14.4V @ 20 amps at full output; no matter what regulator you put on there, that's all you'll get (unless you run it to failure). Even then, running it that hard continuously will kill it rather quickly.

Keep in mind that arc-welder ignitions don't really add any significant power by themselves. On big V8s, a gain of only one or two HP is typical, on a XS you'll be hard pressed to measure the difference on a dyno much less by seat of the pants. You're introducing a large measure of complexity for little or no gain.

And trying to run the coils through a relay opens up the question of switching speed/reliability of the relay. Mechanical would be out, you'd have to use something solid-state.

[3Phase]

It's The Law

Two 3 Ohm coils in parallel in a DC circuit is 1.5 Ohms.

With the stock 1.5 Ohm Ballast Resistor in a series DC circuit with 3 Ohm parallel coils the Primary circuit resistance is -- 3 Ohms.

Impedance is a different issue.

.

[Boneswig]

Yes also thinking of a solid state. Did a PCL board a while ago and ended up with several 12-48 solid states with LED indicators on trigger. So it would actually be an awesome way of seeing when it triggers. Wouldn't the vacuum advance and retard on the pickup plate resolve the tack dwell issue? As far as I could see the vacuum unit is still there, I will know for a fact by this weekend. I'm like n kid 3 days before Christmas. Hahahaha. Bit confused on your explanation on the regulator. The stator magnet generates 40 to 60v AC, which then runs to the regulator dropping it to 12 to 14 volts (think 13.7v max) so even with a 40Ah battery pack the strain will be on the regulator since the stator is only giving AC. Standard XS battery is 24Ah. If the regulator I am looking at cannot take the load I might have to build a diode plate and run a dual regulator system. I will measure the stator voltage (AC) as soon as it arrives, it has a minimum and maximum current and to the death of me can't remember it now. Stator failure usually (90% of the time) is the earth dropping on the inner part of the stator resulting in no magnetic field in the stator. I have seen a XS where the electromagnet was replaced with a magnetic disc. Seemed to work perfect but I would have to look into that one even before attempting such a project.

[Boneswig]

You are correct 3phase. Ohm law applies to this. total amount of ohms devided by amount of components (layman's explination) so 4x3ohm will take me back to 3ohms. Pitty the module can just take one, but if I split up and fit a ballast resistor on each I might just get away with it.

[3Phase]

I'm not clear about how you already made a Golf module work on an XS11 and it purrs like a kitten but you need to change "something" for the bobber project.

Did you use a different module on the first XS?

Which module do you have now?

If the module only handles one 3 Ohm coil, why can't you use two modules to fire the four coils in pairs?

.

[Boneswig]

Ok seems as if I have done something you guys don't know about. So let me explain. On the vw Golf's you have a module. It's basically the same thing as a CDI just on a smaller scale. It has 7 pins. I don't have the schematic infront of me now but wil post it as soon as I get home. I do remember I skipped pins 5 on both of them where pins 4 and 6 went to the pickups. Pins 7 on both of them I had to add diodes to get the correct signal to the tachometer. Else it showed half of what it was supposed to be. On that specific XS he had the standard coils and the modules was connected directly to the original coils without any hick-up or heating problem. I later read that the module recommends a 3ohm coil. With my upcoming bobber project I don't have coils and considered using GY6 coils. Now let me explain why we went this route the first time. XS CDI is a 1500 rand. No guarentee and secondhand. Golf modulator is 180 rand each and readily available brand new at any spareshop. So it's a 1160 saving with guaranteed results. On the coil side (where I am sitting now), two XS coils will cost me 900 rand each, costing me 1800 for the pair. GY6 coils (if I can get the ohms right) is 49 rand each and I need 4. So another 1600 rand saving. So I will be having an extra 2760 rand to play with on the bobber with exactly the same result and during a breakdown be able to walk into any spareshop and just buy it off the shelve. Hahaha ever tried buying a cdi while stuck nect to the road? But with a modulator you just unplug and replug because you can get them almost anywhere. Just seems more logical to go the electrical mod upgrade. Not just because it's a bobber, but I'm not building a showroom XS, it's what I am going to do ralley's with and most of the guys there don't really care if you are running on cdi or module. And there I just convinced myself again that this is the better and more economical route to follow. Hahahaha

[Boneswig]

O and yes I am aiming for that but need 3ohm pairs. So one module per two coils. I just need to get past the 3 ohm problem now, which seems to be resolved with a ballast resistor on each set of coils.

[DiverRay]

How about a Honda or Suzuki dual coil?? Then you are still set up like stock. I know here in the US, there is a VFR if I remember that has some nice hot coils, and they will fit our bikes easily.

[crazy steve]

If you use a ballast resistor, you're going back to halving the voltage to the coils again. That was one of the issues with the XS ignition, the reduced coil voltage when running through the resistor contributed to poor idle quality. Yamaha eventually went to 3 ohm coils and eliminated the resistor.

So you're trying to use 'off the shelf' components, I get that. But rather than use four coils, have you looked for twin tower units similar to OEM? These are fairly common on distributorless ignition systems (I know Ford used these on many of their mid-late 90s motors, I'm sure there's others) that used the 'wasted spark' system. If you can find 3 ohm non-dwell-controlled units, you're good to go.

The 'dwell control' is done in the module. What this is is a way to limit the 'on' time to the coil. At slow speeds the 'on' time is longer (because of the slower speed of the reluctor past the sensor), with 'on' time going down as engine speed goes up. Dwell control electronically limits the 'on' time at slower speeds, so basically the coil is 'on' for the same amount of time for each firing regardless of RPM.

[Boneswig]

Several reason why I looked at the GY6 coils. Firstly they are dirt cheap. Secondly they are very small in size. I can fit three coils on the space one standard coil takes up. Thirdly, if I go for another bike coil (which would have been awesome) then when the coil eventually give in I am stuck again in a situation where I need to spend a lot of money on replacement and once again sourcing a coil. If I take 4 GY6 (readily available over here) and bolt them together I use less space (firstly) and secondly if something goes wrong (and ooooh how Murphy loves me) it's not a too expensive round to backtrack on. I will look into the vfr possibility tho, was actually under the impression that the all of them has coils inside the suppressors these days, but will have a serious look into it. Thanks