Check your belt. Feel for loose teeth. push in each direction, may be broken on one sides and will lay back down looking normal.

 

Surprised no one has mentioned the heat shields on the header pipe. Obviously, they go through lots of heat cycles Expansion and contractions) one after after EVERY engine start. The sound that comes to my mind described a chirp is from dry metal to metal contact, though dry rubber comes close.

 

Yeah... my belt had missing 'teeth' and did that.

 

Mine was "chirping" whenever I hit a small bump and sometimes at idle.
Turns out it was the rubber muffler isolation mounts.
Those things wear out quickly and will start chirping.
Luckily they only cost $3 or $4 at the Harley shop. Easy to replace.

 

Betcha gonna find it's the muffler rubber.
Or, a boid caught in the woiks.

 

Had a 09 FLHTC . It had a chirp on accel and decel also . It tokk almost two years to find it. On the bolt on rear frame section check to see if there is a rust streak on the mounting bolts. On mine there was a bit of rust at one of those bolts. I loosened all 6 bolts a bit and re tightened those bolts . The chirp went away.I assume that frame section was a little bit bound up at assembly which was corrected with retightening .

 

Hey Rucker was it your belt then? My sportster does that also and I'll check it tomorrow. last year I tightened it up. I don't ride that much(5 miles to/from work in the summer).

 

Mine only lasted a few miles until I closed the saddlebag correctly, Felt stupid!