I was riding home Tuesday on my '04 500R and it started hesitating really badly at 5000 rpms, didn't matter which gear I was in it just didn't want to move at 5k. I initially thought I had just gotten some bad gas because the problem started right after I filled the tank up after hitting reserve. I get it home and park it and don't ride it because I knew I wouldn't have a chance to work on it until Friday/Saturday. So Saturday rolls around and I look at the Haynes and Kawa Service Manual(s) I have and start taking the bike apart. After removing the gas tank I pull out the plugs to find that they are fouled as a result of carbon deposits. The Haynes manual tells me it is because my fuel/air mixture is off and I am running too rich. I start looking to the air filter and take it apart. The air box has a "plug" coming out of the foam "horn" piece that comes out of the air-box. I remove that and then take a look at the actual filter. It looks like the filter wasn't exactly fitted correctly when I pull it out. It really isn't all that dirty so I just put it back in. Obviously I am not sure what the deal is so I decide I guess I am going to have to take the bike in for service. I put the fouled plugs back in and reassemble everything. Just for kicks I decide to take the bike out to see if she is still acting up. I get her out and don't have any problems at any rpms. She runs like a top like she used to, maybe even better. Could the possible air filter misalignment coupled with the goofy air box plug have fouled my plugs? How long would would it take for carbon fouling to occur on my plugs? Has this happened to anyone else? I just had the bike service by a Kawa tech a month/1200 miles ago, could something go wrong that quickly with my new bike?