'86 VFR700F1 18K miles last night I changed the plugs on the bike. No idea how long the previous set had been in, but they didn't seem like they'd seen much use, and the gap was fine. However, they came out WAAAY too easy. The electrode, insulator and ground strap were all beautiful, with a very light dusting of grey/tan, and some red on the insulator from the techron. Looks like "good" plugs normally do for fuel in my area. The threads, OTOH, were coated in an amber-brown gunk, usually all the way up to the gaskets, which weren't well crimped down, from their looks. 2 of them had crud past the gasket and hex up onto the porcelein. All 4 were equally easy coming out, and gunked on the threads to the hex/gasket. Last person to do plugs not torque them down properly? They were the stock Nippon Denso plugs listed for the bike. I put in the stock NGKs listed, and torqued as spec'd (1/2 turn after seating the gasket by hand). Wish they'd put torque numbers on the things... Upside is it starts better now, but I want to make sure that it was just unburnt fuel blow-by from loose plugs vs. something worse (doesn't seem to drink oil, and the plug tips looked fine). Thanks,
Sounds like they were just a little loose. If they have been shaking around in the holes, they may have worn the threads in the heads. I'd keep a check on them to be sure they stay tight. You might put a little anti-siez on the threads to keep them from sticking in the heads.
I finally got to ride the bike today. Big difference. Way huge big difference. Exhaust tone changed, too. I'm certain I was getting some compression loss around the plugs. I'm sure the new air cleaner helped, too (problem with fixing a bunch of stuff at the same time). But it doesn't make the chuff-chuff sound to the exhaust that it used to, and I'm hearing less engine noise in general, and a more solid exhaust note. At least, I think I am... Might just be maintenance syndrome.
