I'm presently helping a friend rebuild her 20 odd years old Bukh.There was water in the sump wich turned the oil into a gooey mess with the consistency of very thick peanut butter.She had the good sense to stop the thing when she detected a change in note so damage shouldn't be very extensive.The point I'm trying to make here is that this engine is unnecessarily complicated and, of course that reflects on the price.There are counterweights everywhere and also an advance and retard injection timing system.Its weight is astronomical no doubt due to all those extra bits that you don't find in more modern and equally (if not more) reliable designs.
That external flywhell is to say the list menacing and the engine is at least twice as big as my 20hp Beta.
People may say that it was designed with marine use in mind and that they last for ever.Aparently they last for 20,25 years with a few rebuilds along the way.Don't get me wrong this is a good engine but a flawed one.The raw (and only) water pump is patently undersized and for this reason these engines are known for steaming a lot at the exhaust and warping their cylinder heads.
I know of a raw water cooled Kubota that's at least as old as this one but a lot more reliable.
And they are not smooth.At least not at idle speeds.They do vibrate like hell at low revs.
Wer're going to fix it ,nothig more serious than a failed Oring we hope.But I wouldn't buy one new specially not based on reliability.I can get much less expensive engines on the market wich have evolved with time something Bukh failed to do.
By the way I had a Bukh in my Fulmar when I first got her but now there is a little sweet and powerfull Beta in its place.Best decision I ever made,although I have to say I miss the hand start facility.