Intake issue or not (see pictures)?

[Phil]

Looking for common knowledge and advice.
This is about a GS850GT ('80) of 45k km. About only 200km from a crappy engine rebuild.
I have been told by the last owner who was told by the previous one that the engine head was changed. The bike came with another dismantled head but without any maintenance log available, I canot confirm it has effectively been changed.
Anyway, what do you think of these intakes condition? What is causing this black deposit on #3&4?
Does this need corrective maintenance of any sort?
Thanks
Phil
PXL_20220331_213538854_2 by pwauthy
PXL_20220331_213614087_2 by pwauthy
PXL_20220331_213630049_2 by pwauthy
PXL_20220331_213638540_2 by pwauthy

[zed1015]

That's the result of being run a very long time with worn out valve stem seals and likely long term blowback from badly seating valves.
Either that or it's been dredged up out of a river.
That's some of the worst deposits i've seen on the intake side.
1 and 2 may have had water sat in there if the heads been sat outside or open the the elements.
That head needs a total strip, a complete valve job with stem seals and very likely new guides etc.

[Phil]

Thanks zed1015 .
I followed most of your advices but never showed the result.
Assuming better late than never, here it is.
PXL_20220902_191220377 by pwauthy
PXL_20220902_191305330 by pwauthy
PXL_20220902_191530707 by pwauthy
PXL_20220902_192330101 by pwauthy

[allojohn]

Sweet! Nice save Phil.