Ignition Module Wires, Repair Advice

[RF47]

Hi, I have a 912 ULS with ~190 hrs (on a Kitfox IV on straight floats). Very close to the harness's plug for the ignition modules I found some bad wires, one that was broken under the coating, and a few others near breaking. The wires from the ignition modules are short to start with, not leaving much to work with. I have been going back and forth regarding the best way to fix this and am debating between the following choices;

1) Shortening all the wires to remove the portion closest to the plug and crimping on new terminals. This will remove the portion of the wires that were work-hardened during vibration of the connector, but result in a very short harness (which should be fine).

2) Cut all wires near the module, then use shrink wrap butt connectors to secure new longer wires (with terminals, and plugs). This should be secure, although 12 butt connectors so close together may make for a large bundle that will be vibration prone.

3) Cut all wires near the module, then solder on and very well secure new wires (with terminals, and plugs). I am not a big fan of this, as the solder joint could be a common point of failure in the future unless very well secured. I generally try to avoid soldering for aviation work.

4) Order new Rotax (Ducati) ignition modules. This is the least desirable option as the modules I have work just fine other than the poor wiring. The modules are not inexpensive to say the least.

5) Order new aftermarket ignition modules. I found an individual (Allistair Wilson) that sells new modules with the soft-start built in for ~$250 each. I have no idea if these are good quality and safe, although I did speak with him and he was very knowledgeable and helpful. But again, $500 for new modules vs ~$25 for new wire and connectors to fix my existing modules is a big difference if the outcome and safety is the same.

A last note on this, at the same time I will be moving the modules and coils to the solid portion of the engine mount to reduce vibration on them. This however has its own drawbacks, as now the wires from the trigger to the modules, along with the spark plug wires, must flex as the engine moves relative to the frame. Despite that, this is likely the way I will go to reduce vibration of the modules and coils themselves.

I know this is a fairly common problem, but I can't locate specific direction on solutions. If you could please lend your advice for items 1-5 above, or offer an alternative solution it would be great! Thanks in advance for the guidance with this, much appreciated!! Rick

[4Hummer]

#3 solder.

Butt connectors have no place in an airplane.

[RF47]

Thanks for the quick reply 4Hummer. I think you are right, a solid lineman's splice with minimal solder, coupled with good fixation of the wires to avoid movement should be plenty strong. Thanks! Anyone else care to chime in, or have experience fixing this?

[109JB]

https://www.amazon.com/TICONN-Connectors-Waterproof-Insulated-Electrical/dp/B07HCNTZ2Z/ref=sr_1_1_sspa?dchild=1&keywords=solder+splice&qid=1623289356&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFWOVkwUzRIRTZDNlImZ W5jcnlwdGVkSWQ9QTA1OTUxMzcxN0IwNFlaMkRKODBJJmVuY3J 5cHRlZEFkSWQ9QTAzODU2NTBZWTlTSDJUNjUyT0wmd2lkZ2V0T mFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3R Mb2dDbGljaz10cnVl

[jrevens]

#3 solder.

Butt connectors have no place in an airplane.

While I'm not a particular fan of butt connectors in general, there is absolutely nothing wrong with using properly sized, good quality ones (AMP, T&B, etc.) on an airplane, IMHO. It's best to use the ones that crimp & hold the wire insulation as well as the wire, for strain relief and support. They need to be installed with the proper tool. This type of electrical connection is used on a large percentage of factory-built as well as homebuilt aircraft, of all kinds, for wire terminal ends, Faston connectors, butt/splice connectors, etc.

I do personally like soldered connections, well-made, and using adhesive-lined heat shrink tubing to seal and stiffen the joint for a small distance, to prevent flexing at the solder-stiffened wire joint.

The key with the Rotax ignition modules is to keep the wires that exit the modules from flexing/moving in relation to the modules for a distance before allowing a small, reasonable amount of flexing as necessary.

[RF47]

Thanks John. This is a bit of a silly question, but do you think there is any chance the low melting-point solder in these type of connectors (~115C) would get anywhere near hot enough to re-melt while running?

[109JB]

Thanks John. This is a bit of a silly question, but do you think there is any chance the low melting-point solder in these type of connectors (~115C) would get anywhere near hot enough to re-melt while running?

According to the specs, it takes 280 deg F to melt the solder. I would not be worried.

[avidflyer]

I bought one of those modules from Allistare Wilson. I tried it on the 912 UL, and it worked fine. Ended up not needing it and so it's in a drawer waiting till I install the ULS and I will use it on that engine cause it has a soft start module built into it. I would not hesitated to get another one if needed. I also moved my modules to the firewall side of the motor mount to avoid broken wires in the future. If I was you, I would maybe fix both modules you have, install one of the aftermarket ones, and have a spare Rotax one if you ever need it. JImChuk

[jrevens]

Thanks John. This is a bit of a silly question, but do you think there is any chance the low melting-point solder in these type of connectors (~115C) would get anywhere near hot enough to re-melt while running?

Not at all silly… as John B. said, it shouldn’t be a problem. However, “solder sleeves” have gotten mixed reviews from people. Bob Nuckolls was (is?) a fan, but then noted some problems with them…. incomplete or poor flow of the solder into the wire for one thing, I believe. I think variable quality may be an issue, like with so many things made in China especially. That’s just my personal opinion and experience.

[Rodney]

Just put on a new set of modules from Alistair Wilson. They are really well made and he was a pleasure to deal with.

My engine just would not run on the "A" side of the ignition. I traced everything I could; You have to understand I'm very limited
when it comes to electronics.

What I eventually found really surprised me. I had four bad spark plugs - all on the A side. I've never had that happen before.
I replaced all the NGK spark plugs with Champions and my engine is running fine. The reason I went with Champions is that I live in
a small community and that was all I could get. Even had to go to two parts stores to get a collection of 8 plugs.

Still - I like the modules I got from Alistair - very easy to install and I moved them away from being on top of the engine.

Regards
Rodney

[WWhunter]

I bought one of those modules from Allistare Wilson. I tried it on the 912 UL, and it worked fine. Ended up not needing it and so it's in a drawer waiting till I install the ULS and I will use it on that engine cause it has a soft start module built into it. I would not hesitated to get another one if needed. I also moved my modules to the firewall side of the motor mount to avoid broken wires in the future. If I was you, I would maybe fix both modules you have, install one of the aftermarket ones, and have a spare Rotax one if you ever need it. JImChuk


As Jim mention, probably a good idea to have a spare. I had a persistent issue with my modules several years ago. Substandard wire in them (in my opinion). Several areas of the wires broken inside of the insulation. I had to cut/spice/repair several sections of my modules and wires from the stator.

Granted I come from experience in building military grade electronical test equipment for fighter aircraft, so was used to using very high quality wires. The wire that Rotax (ducati) uses is pure junk!

[RF47]

Thanks everyone, appreciate the input! I ended up buying two new modules from Allistair. I will also redo the wiring on my old Ducati modules to keep as a backup set. I'm lucky enough to live down the road from Rotech, so I went and talked to them about repairing the modules. Once I get it all complete, which will likely take a while, I'll try and post a couple pics in the event it can help someone else out. Thanks!

[napierm]

Yes, crappy wire! I had to buy a replacement module for my 912ul and the cost was eye watering. I could buy a new magneto for that price! You would expect better quality for the money.


As Jim mention, probably a good idea to have a spare. I had a persistent issue with my modules several years ago. Substandard wire in them (in my opinion). Several areas of the wires broken inside of the insulation. I had to cut/spice/repair several sections of my modules and wires from the stator.

Granted I come from experience in building military grade electronical test equipment for fighter aircraft, so was used to using very high quality wires. The wire that Rotax (ducati) uses is pure junk!

[Birdseyeview]

Who is this Alistar that you're all talking about and how do I get a hold of him for a price on modules with the "soft start" feature built in?

[desertdave]

Who is this Alistar that you're all talking about and how do I get a hold of him for a price on modules with the "soft start" feature built in?

Here you go Larry:
https://barnstormers.com/classified-1604831-Rotax-CDI-Boxes-4-and-6-pin.html

ROTAX CDI BOXES 4 AND 6 PIN (https://barnstormers.com/classified-1604831-Rotax-CDI-Boxes-4-and-6-pin.html) • $245 • NOW AVAILABLE • New aftermarket CDI Boxes for Rotax 912 and 912 S engines with inbuilt soft start. $245 plus S&H. • Contact Allistair Wilson (https://barnstormers.com/contact_seller.php?id=1604831) - SPORTFLIGHT INTERNATIONAL LLC (https://barnstormers.com/contact_seller.php?id=1604831) , Owner - located Bloomfield, IN United States • Telephone: 812 384 4760

[Maverick]

What is the concept of "Soft Start"? I've seen it referenced but, I don't really know what it is. Would someone care to edify me?
Maverick

[avidflyer]

The soft start, at least on these aftermarket modules uses 12 volt power from the wire going to the starter solenoid switch for low rpm spark. When the key it turned to start position, starter engages, and ignition module is energized. Otherwise the modules don't generate spark until about 300 rpm. When key it turned off start position, solenoid and module don't receive 12 volt power. JImChuk

[napierm]

AND it is "soft start" because it retards the spark timing (hopefully to just after top dead center) for a couple of seconds to help prevent kickback. That's a problem on 912uls and will damage the starting clutch.

[WWhunter]

Yes, what the two previous guys stated. It basically retards the timing on ONE module (you're suppose to start on one module and then turn on the other module. I have mine wired to two toggle switches. One for each module. Bullyhawk was the seller I got mine from, but not sure if they are still available.

[Maverick]

It basically retards the timing on ONE module (you're suppose to start on one module and then turn on the other module.

I have never heard this before. I always start mine with both ignitions turned on. Why would you only start with one ignition?

[WWhunter]

I have never heard this before. I always start mine with both ignitions turned on. Why would you only start with one ignition?

I may be wrong on that, but I'm thinking that's how the instructions for the Bullyhawk unit stated. Now this isn't the same as the factory modules with soft start. Two different things, apologies for getting off topic.

[atosrider]

This topic caught my interest, and the timing was good for ordering new modules during the rebuild of my 912UL powered K3. I did not suspect damaged wiring at the connectors, but they are almost 30 years old now so why not refresh.


While trying to get up to speed on ignition system refurbishing, it occurred to me that the potential vibration loading on the 100hp on straight floats would be far greater than an 80hp on wheels. There are no brakes on floats, and the 100hp wants to idle higher. So, maybe this exercise was not required – oh well, it will feel nicer to be up there with newer equipment.