quirks that don't go into repair manuals
on old 1st gen SV650s, sometimes the would bog down at higher rpm, but run perfectly at lower rpm, what was happening, to meet EPA sound levels, there was a sheet of foam glued to the underside of the fuel tank to reduce intake honk, the foam would come unglued and sucked away from the tank blocking the air intake, but go right back into place if you had the tank off to look