sometimes i have a slight sound at 3800 i can't explain it well though, kinda sounds like when you take 2 blades of grass in your hand a blow through them kinda a vibrating squeel.? only lasts for a second or so. i don't have any hesitation though. and it only happens the first couple times a open it up after warming it up fully

 

I have the same thing if I try to coast at 3800 i feel hesitation, and the same sound you describe. My impression was that it's a change in a/f ratio at 3800, cause you'll obviously notice after 3800 the power just cliiiimbs.

 

no i don't have any hesitation at all throughout my rpms, only the sound.

 

same here, and then the sound just stops at 3800. I have yet to find what it is yet.

 

could be the manifold to downpipe flange, i have seen them warp slightly causing the gasket to make a reed fluttering noise as the exhaust leaks but goes away at certain RPMs due to air velocity.

 

is this the same as my engine hesitating at 3800 rpm's, then making a "spooling up" sound, and shooting foward. I'm riding an NA

 

Mine hesitates before 1.8K RPM, u push the gas lightly which will coast it at 3Kish but it goes SOOfaking, yes a sofa and king slow till 1.8Kish then SHOOTs up to 2-3K

 

None of the above.

It's the ACV dumping at 3800 rpm as it's supposed to. Either you have excellent hearing or the silencer for the ACV is disconnected at some point.

 

I have excellent hearing