YAMAHA 1998 corrosion issue

recently bought an old 1998 Yamaha 75 2stroke. Was in pretty bad shape with poor compression in the lower cylinder. Got a good price with the aim to restore it to her former glory. After opening the heads found massive salt build up and corrosion, didn't look like the previous owner ever flushed the motor out. Found a hole in the lower cylinder head cover. Pulled off the exhaust outlet water jacket and after clearing out most of the salt build up I found a lot of corrosion on the block itself. Does anyone know if these holes are part of the cooling system or corrosion, and if so would JB weld type products be sufficient to plug them or would it be better to try weld them. Compression on the cylinders was 80-70-10.

The 10 PSI is a concern.-----Was it a blown head gasket ?----Scored cylinder ?-----Might have to take motor apart for a complete evaluation!!

hi, thanks for the reply.

there was a hole in the cylinder head which I thought would be the main factor for low compression. I think water had been getting in from there or somewhere else as there was a milky white substance around the piston, which I have read is water and fuel/oil mixing. The spark plug was also wet and showed no sign of carbon build up, where as the other two looked like they had been firing. The motor does run however when I took it out on the river it would not reach full revs. Running on 2 cylinders only?

If water had gotten to the crank shaft assembly would there be a high chance of rust damage, as I said I bought it really cheap but don't want to end up spending thousands to get her running again.

Is there anyway to repair corrosion on the block itself on is a whole new block needed?