the plug for your f41 is the same as my 954, i beleive, depending on year. the ngk number is IMR9A-9H, and the autolite plug is a 4302. You should be able to buy these plugs at about 10bux a piece, and the work yourself isnt very hard, as long as u take your time and do everything right. I never worked on a bike engine before, and i was able to get mine in and out in about 45 mins.

check advanced or autozone, have them order the plug. Or try sparkplugs.com i hear good things about them.