Well all this has been unrelated to my original questions but just to give y'all an update. I used heavy duty zip locked bags and covered each piston sleeve with three of them. I pushed them down to the bottom of the water channels. I then used gorilla tape and tapped over them. I did not know if the fumes from the solution would affect the steel components so to be safe I just protected everything as much as possible. Using my motor hoist I hung the engine block and put it into the solution. The hole with the broken tap is on the corner which allowed me to only dip that one corner in the solution. The sleeves never touch the solution but I did not want to take any chances which is why I covered everything up. I brought the solution to a simmer and let the bolt hole sit in solution for 24hrs. I started at 5pm (after work) and every 30 mins I took a small pick and scrapped the tap so the solution would have a fresh surface to make contact with and allow the chemical reaction to take place. I added small increments of water when needed to allow the bolt hole to be fully submersed. At 1am I added more water, little extra than needed because I was going to bed, turned the burner off, and let the bolt hole sit in the solution. When I got back from work the next day I took the block and sit it on my work bench. I took all the tape and plastic off, cleaned the tape residue off, and to my surprise found that the solution did not touch that beautiful Yamaha paint on the outside of the block! The broken tap was still there but you could see a gap between the tap and hole wall. I started poking at it with a small pick and found that the tap just started to break apart. I removed as much as I could with the pick but I could not get to the bottom of the hole. I placed the block under my drill press, took forever but finally got everything lined up right, and using a carbide tip drill bit that I got from Lowes for $4 I was able to remove the remaining parts of the tap. I took the block to a local machine shop and they are installing a thread insert, WHICH I SHOULD HAVE DONE IN THE FIRST PLACE! Lessoned learn for sure. The shop is only charging me $35 to do the thread insert but they originally quoted my $250 with the broken tap. The ALUM solution costs $10 for 1lb on amazon and I had to buy a disposable aluminum pan, tape, bags, drill bit. Over all it cost me $30 to remove the broken tap myself.
***Back to my original question about the plug hole. I have a tig welder capable of outputting 250 amps that I weld aluminum with but I have never welded an engine block. My current plan of attack it getting a 5052 Aluminum solid aluminum rod, cutting it to 1/2" length, and welding it in place. Can anybody think of a reason why not to take this approach? I know I would have to preheat the block and only do short increments of welding as to not over heat the block and cause damage. What other option do I have?
