Longer Plug Wires

Hi Scott

A - easy to make

B - NO NO NO, this is not automotive grade wire.  Today's auto engines use high power discharge systems and the wires are no longer copper stranded inside.  Todays wires are normally carbon core...no good for this application. On this (relatively speaking) low voltage system get the correct wire. Bulk wire is available from any Rotax iSC, independent Service Center. 

C - See above...

The Rotax wire is stranded copper.  The wire threads into the coil and also the connector.  Be sure to use the vinyl sleeves like the original, just take them off your existing ones.  Use dielectric grease on each end when you connect.  The heavy maintenance manual, HMM, shows how to do this.  Be very careful here because you have to allow for the engine movement on startup and shutdown so that the wires are not pulled.  Also they need support to not bounce too much.  I would be very concerned with the connections to your modules as it sounds like you want to relocate them as well.  My suggestion is go to a Kitfox forum, they have a lot of really good people to help you with how they might have done something like this. 

One last thing.  The longer the wire the higher the resistance.  You only have about 20K ohms to work with on the 912 system so don't make them silly long....

Cheers 

I remade my old leads using some standard non-resistive 7mm copper-cored HT lead. The NGK plug caps just screw on like the coils. The more difficult part is the adhesive-lined heat shrink tubing that is required to cover the HT lead including the nose of the coil.

I cannot remember the total length that I needed to replace the existing length leads.

Thanks for the great info.  To be clear, I was not ever considering using auto grade wires.  I was going on an assumption that I could source some ROTAX pre-made wires.  But it sounds like I can just source the raw (ROTAX) wire and make my own.  The sad part about all this is I only need to make them about four inches longer, but as they are now its just too short.  Another assumption here is that an addl four inches shouldnt add enough resistance to be an issue.

Thanks again for your insight.

The resistance of a copper-cored HT wire is negligible. You are going to add about 5 kohms with the plug cap anyway so a few more milliohms won't make any difference.

Can anyone explain the function of the vinyl sleeves, what makes them so important? If the are supposed to hinder water sneaking in I can picture that, but is there anything else to them?