Join Date: Jun 2008
Location: Lethbridge Alberta
Model: 1999 GL1500 SE 50th Annv.
You need a set of 7mm copper core wire plug wires. To my knowledge you can't use a silicone center wire on this year of bike. I got a set of 8 (7 mm copper wire plug wires) off ebay for about $10.00 and they work fine. ( I end up with a spare set) They only come with the plug end attached to the wire so you'd have to get the coil ends and you have to get a set of threaded tips off an old set of plugs to put on the plug wire end of your plugs. Auto style wires use the bigger end on sparkplugs.
Hard to say without seeing it, wheither the broken cap will not let the plug wire stay in place. You can check the coils for resistance, just put an ohm meter across the two plug caps on each coil ( plug wires off ignition off) Resistance levels should be about the same for both coils. You can check the plug wires the same way both not pluged into the coils & plugged into the coils. I can't recall the actual resistance level, but you can do a search or check a manual. Coils normally cause problems when they are heated up.
1983 GL1100, 2013 Suzuki Vstrom DL650
Previous bikes - 1971 BMW R75, 2008 HD Softail, 2000 BMW R1100R, 1980 XJ650, XT500, GS550, 77 GL1000 x2 and a few others