Ok first time here so thank you for any help.this motor was bought new by me its has maybe 200 original hours on it and 50% of those hoirs are from idling around bowfishing.the other hours are very mild just open water riding with the occasional getting in a little mud.the boats life has been used occasionally and will sit for a couple of months and then used again.during the times it would sit at least once a week it would be cranked up and ran for a min or two.the other day i went out to crank it and it cranked right up but started making a strange noise and would get worse when reved up then it went away. It only happens when first cranked then goes away.so i took it out to test in water.once cranked the noise was very noticeable then once the pto was engaged the sound stopped so i turned pto off and sound came back pto it stops 4 hours into the test it want make the noise anymore.if i let it rest for awhile the noise comes back

Clicking? Groaning? Growling? Clanking? Etc. Where exactly is it coming from? When did you last check valve lash?

#CFFITR
#GhostBoat
#Whoneedsphysicsihaveamudmotor

Is the noise coming from the clutch? I had one do something similar when mine was going out.

Sounds exactly like the clutch, 200 hours is about the normal lifespan of ones that aren't used everyday, some get more, some get less. Like banded said, it'll get rust on it and you probably wore it off and that's why the sound went away. The plates are barely scrapping each other.