Post by
VStar650CL »
https://forums.nicoclub.com/vstar650cl-u299034.html
Sat Feb 27, 2021 9:10 am
Might be piston-slap if it goes away that quickly and stays away, but there are some other things that can make weird noises cold like alternator clutches. I'd get a stethoscope and see if you can locate it. If you hear it loudest from the side of the block then it's probably slap, go to a bit thicker oil and it should help. It could also be an issue in the oiling system causing the top end to starve when cold, if that's the case you'll hear it loudest in the head and/or valve cover. That could be something like a bad oil pump check valve and not necessarily low oil pressure in general.