Check a couple of things first:
1) Check the nuts holding the header pipes for proper torque. If they're loose, there could be a small exhaust leak causing the problem. DO NOT OVERTIGHTEN, again, proper torque!
2) When COOL, check the header pipes for small cracks. Same thing, exhaust leak could be the culprit.
If neither one of those is the issue, a TFI and/or marbling can help as well.
BACA Pretzel - Flyin' the highways in OK!
'08 Vulcan 1600 Nomad - "Grace"
Metallic Diablo Black/Candy Fire Red
Vance and Hines Duals
Kuryakyn Flame grips with Throttle Boss and Stiletto endcaps
Kuryakyn Longhorn offset highway pegs
Vista throttle lock
OEM light bar and luggage rack
B.A.C.A. Member, Oklahoma Chapter
Out to pasture - 2008 Vulcan 900 Custom: Redemption