Out on the lake today, running my 1998 BF 90 after a month of sitting in my garage on the back of a Godfrey Marine 18' Hurricane deck boat. Good gas, started right up, with a little puff of blue smoke, as usual. Water pump sending a better stream than my own bladder (no surprise at 80). Ran it at 5500RPM for a tour of the lower half of Conchas Dam NM. Water temp 72. Slowed to trolling speed for half an hour, then decided to run north for 20 minutes to the "Narrows" to do a little deep Walleye trolling. I decided to max it out at 6200 RPM for a couple of minutes (I don't usually do that, as I try to plane at 24/5 knots, rather than the 32 I usually get at fuill throttle. I pulled the power back to 5500, and after acouple of minutes, a big puff of blue smoke, loss of power, and engine clanging erupted from my babied BF90. I immediately killed it. Went three miles on the trolling motor back to the boat tock, trailered it (nice day - to get wet), and RTB'd. Once in the garage, I checked the timing belt - intact. Oil: Pure sythetic, newly changed and clear on the dip stick. Pulled the plugs. Topp three: pure. Bottom plug: Tough turning it, once out, smashed. Electrode pounded into plug base.
I suspect lower end bearing failure, or something like that.
Any suggestions: Rebuild, repair, replace?

 

You have a lot of time on that motor?
If so I would buy a replacement. It will require a total rebuild and you could have block issues. Either way it's bad.