my buddy has a 111 S&S. rootin on her pretty good. suddenly loss of power then as soon as he lets off throttle it dies. pulled the heads and no obviouse sign of damage. the top of both intake valves ( the top being the part of the valve not facing piston) id heavily carboned up. big pieces. pretty good buildup of carbon on the cylinder walls at TDC. no bent rods but very hard to tell if valves are seated. put rear cylinder at TDC and put air to cylinder through spark plug hole. had some air out of exhaust. is there a chance carbon broke off and caused valve not to seat?

 

If it is at TDC on the exhaust stroke, the exhaust valve will be open...pretty simple to check if the valves are seated with heads off...put the plug in, fill the combustion chamber with water.

 

Rubbing alcohol(not for drinking), it shows up leaks better, and doesn't make things rust.....

 

Have you called S&S to see what they suggest?

 

May be a dumb question, but did you do a compression test before tearing it apart

 

I had an ignition module that went bad and act similar to that, rear cylinder spark was weak and firing randomly out of time, no idle and cuttin up and occasional backfire if trying to accelerate.

 

If it has a module in the nose cone the wires can rub and short out too.

 

forgot the adapter for compression tester. he wanted to pull the heads and have a look. also found very thick coarse carbon buildup on the intake valves on the top side of valves. not cylinder side. also heavy thick carbon around the top of the cylinders on the perimeter where the cylinder meats the heads. hes gonna have our local independent wrench here clean up the heads, new valve seals, and rering and break glaze on jugs.