if the boat sat for a while and hasnt been ran that could be the issue. heck my boat sits for just the winter and with fogging oil and being carbd the thing usually chockes and spits for the first while.

Get a professional to check it out, price may dictate it as well.

I'd walk away. The engine was damaged, and slapped together. Anytime a engine takes out a piston, i'd want in fully torn down, cleaned, inspected, and reassembled. If it holed the pistons, i'd assume some aluminum got into the bearings.

Not even bothering to pull the other cylinder head? Cmon.

Buy it. Call yourself James Bond as you lay down a smoke screen.

You guy's are such scarety cats. Buy it right run it till she blows but probably just need a set of plugs and airing out.

My first thought was 2 burnt pistons = out of round cylinders in those holes. If you see blue smoke like you say there is big trouble and the engine needs a complete rebuild/bored and all new pistons. That's probably worth 4g to get fixed. And if you run it as is it won't last and will be 6-8g to fix after it blows and causes damage. So if I could get it for 10g less than his current bottom dollar, I'd be fine with it but know I have a lot of work to do before first launch. If I didnt want to do the work I'd surely move along.

I know 1 piston had a small chunck break off (just above the top compression ring) and got fused to the top of the piston. It was in a spot where it didn't hit a valve. I actually have a pic of it. I looked and felt the cyl walls while it was disassembled. They seemed fine and the original cross-hatch pattern was clear.
I believe the other piston suffered a similiar fate.. The owner did come down abt $6k.
The eng was blueprinted so I should be able to get a new set of pistons and shave them to regain the balance. I'm assuming a new set of forged KB pistons will run abt $1K by the time they are ready for install.

Got an experienced Merc/boat guy going to check out the transon and stringers tomorrow. If that goes well, I'll probably be making my counter-offer.

If you're willing to do the work I say go for it if everything else checks out. Just know its not the gas making the blue smoke and the engine is not going to get better without doing the work. BTW, you need to measure a cylinder to see if its still round, eyeball no worky.

blue smoke is oil...not gas. If it is still smoking you have other issues as there must have been more damage than was seen. My guess is that maybe some rings are sticking.

The owner stated he thought the old fuel was making the blue smoke. Think it was wishful thinking on his part. I will be doing everything except the machine work. Probably be ordering the pistons/rings from the company that put the bottom end together since they did the original balancing and they have the documentation.

Will definately be checking cyl bore with an inside mic.

Maybe you'll get lucky and only need a couple more pistons and the bores are ok. Good luck with the purchase.