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Author Topic: Ignitech, coils, leads and plugs compatibility  (Read 1802 times)
koko64
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« on: June 09, 2019, 07:36:57 PM »

IMG_2171 by Tony Kokonis, on Flickr
« Last Edit: June 09, 2019, 07:39:22 PM by koko64 » Logged

2015 Scrambler 800
koko64
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« Reply #1 on: June 09, 2019, 08:38:08 PM »

Having read and reread the Fastbikesgear Ignitech manual, I came to the conclusion that my Ignitech ignition module in my hi comp M900 could use more optimum or more compatible ignition components. Or to put it another way, there may be some incompatibility between components which are in themselves excellent parts. For example, Nology coils have a bad reputation when used with some stock ignition systems (Desmotimes Desmodue Manual, LT Snyder).
FBG are very clear about the Ignitech units requiring low resistance coils, non resistor caps and low resistance leads, but resistor plugs to prevent RFI/EMI.

In an attempt to find a reliable and performance oriented ignition combination like many here, over the years I have run various combinations of aftermarket coils, leads, plugs, plug caps, etc. Nearly all the parts I have tested have been good components like Exactfit and Dyna coils, NGK or Magnacore leads, NGK plugs, etc. The issue is parts compatibility. This Kiwi tuning house claim to have conducted plenty of testing on the road, dyno and with a good ol' osciliscope to gather some data around parts compatibility for those running Ignitech ignition systems on carbed desmodues.

Being a skeptic and wary of snake oil (or in this case Kiwi oil) I thought I would test the recommended combination out for myself. I tested the recommended components from the FBG manual which comprised of the following:
1. Nology special order low resistance coils (yeah, Nology I know), (Art. Nr. 355 1 00). I think they are 1 Ohm. Apparently built in Germany to order for the Ignitech units.
2. Copper core plug leads with silicon coil caps.
3. Non resistor plug caps (yeah I know). I used NGK LZFH 8381, like the ones you use on old magneto equipped bikes
4. NGK resistor plugs (DPR8EA-9). These were stipulated for use as we here all well know. There have been Ignitech failures associated with the use of non resistor plugs.

My first test was to check for RFI with my old ute, so radio and motor on and the bike revving in close proximity. Check.
Low idle test on the old girl. Check. Very even firing on each cylinder and the best idle the bike has had with FCR41's. Distinct firing of each cylinder with no fluffiness. Carb settings did not change. I had to back off the FCR idle knob half a turn. Impressive.
Low rpm operation in the estate which is built like a rabbit's warren. Very smooth and responsive.
Higher rpm operation on the open road. Smoother cruise and snappier roll on response with quicker rpm pick up. No carb changes. Not a giant leap forward but incrementally better.

The biggest change was idle quality, it was a significant improvement and on par with my stock '99 M750.. Cold morning starts required less accelerator pump squirts to fire the motor. FBG claim that the use of resistor caps and higher resistance coils increases misfires with the Ignitech unit. They also claim that the custom Nology coils have a very fast rise time which is good for wasted spark motors like the Kokusan equipped, inductive pick up desmodues.

What this means for me is that the use of Kokusan boxes requires a return to resistor plug caps and 3-5 Ohm coils like oem, Dyna or Exactfit coils. My M750 has a fully stock ignition system and with carb tuning, idles beautifully.

I'm no ignition expert, but like many here have tried many component combinations over the years in the search for better performance. To illustrate how component compatibility is paramount I once worked on a '66 BSA 650 Lightning with incompatible ignition components. The bike had leaking Amal Monoblock carbs (you young 'uns look them up) and had already caught fire previously. The refurbished bike still had leaking carbs, but these were only part of the equation. While tuning the rebuilt carbs I  noticed a flash in the corner of my eye  thinking one of the flouro lights in the workshop had begun flickering, but upon closer inspection and to my horror the Lightning was issuing forth lightning! I rang a crusty old biker from up north who specialises in old English iron and described the ignition components fitted by another shop. The parts were dangerously incompatible.
« Last Edit: June 09, 2019, 09:05:14 PM by koko64 » Logged

2015 Scrambler 800
greenmonster
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« Reply #2 on: June 10, 2019, 03:23:43 PM »

 waytogo

Gotta try this once I fire the old girl up, was hard to get decent idle w my FCR`s.
Green Dynas is the least bang-for-buck mod I`ve made.
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koko64
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« Reply #3 on: June 12, 2019, 06:08:59 PM »

Gday Gert

Green Dynas are 3 Ohm and black Dynas and Exactfit coils are 5 Ohm-ish. The coil/plug cap combo really helped idle quality with that large throated carb. When correctly tuned, the 39's idle better and run cleaner down low imo (although I've only tuned four FCR 39's).
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koko64
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« Reply #4 on: June 12, 2019, 08:57:42 PM »

Another thing I recently learned from the fastbikegear ignitech manual is that its probably better to run the pick ups 0.5mm from the lobes for a stronger idle as the inductive pick ups give a weak signal at 0.7mm. at idle speed. I run a faster idle with a light flywheel (1300rpm) to compensate.
I do wonder how much alloy flywheels expand out when hot effecting safe clearance.
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2015 Scrambler 800
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