[FATGOLD]

04 fatboy bigshotlongs,bigsucker,pcIIIusb got a hell of spark knock at a higher rpm if i get in to it off the line it rattles bad it was there before i installed the air filter and the pcIII. Ican go up a hill and there's no knock but if im on the highway and i crack into it it's there.I ran the bike for about a year with factory baffeles drilled out and never had the noise. Over the winter i installed the vance&hines bigshot longs. Didnt have enough dough for filter and the pcIII. So i ran the pipes anyway. My theory is if you change the air filter and its going to let more air in then i believe thats when you need to richen it up .Of course you need to watch the oil temp. But anyway been riding it for about 5 months with just the pipes. over the weekend i put a ness sucker,pcIII thinking it might solve my knock problem no luck it gave me a crispier throttle response and thats about it. Im thinking about changing the plugs since they'er oem's and they look like a piece of gray charcoal. JUST LOOKING FOR SOME FEEDBACK. The bike has 8500 miles onit and the dowload i put in the PCIII was 805-176.(should i go with a hotter plug?)

[edgehaha]

Sounds like you need new plugs! Change those plugs with stock ones. From spark plug condition, it sounds like you were running lean. http://www.rmh-d.com/service/spark_plugs.php When you do a upgrade like that, the PCIII should be the first thing you get. The pipes are without question the coolest outward part of your upgrade, but dealing with your fuel is top technical priority.

That Twin Cam 88 is well engineered I'm sure you didn't hurt it. Change those plugs ASAP and be sure you get the right map. For big shot longs PCIII gives you 2 options; with or without baffles (M805-177).

For my Dyna, I'm making the assumption that the Arlen Ness Big sucker is close enough to the SE air filter, but eventually I'll get my scooter to a dynamometer to finalize my PCIII map. http://en.wikipedia.org/wiki/Dynamometer