I think they're 7mm, they're slightly thicker than a quarter of an inch at least, don't think they're 8mm.
The wires I have seen are not shielded, and you probably don't want resistance wires either. Most automotive spark wires these days are resistance wires (carbon wire) while the sleds have resistor spark plug caps and regular multi stranded copper wires.
A forum community dedicated to snowmobile owners and enthusiasts. Come join the discussion about performance, racing, troubleshooting, trails, maintenance, riding tips, modifications, classifieds, gear, and more!