A Series rebuild cost

[Lukey]

Got the engine today, it was a nightmare took around 5 hours but he let me have everything for £25 including all ancillaries.

Took the head off a small amount of water was sitting in cylinder no 4 it had created a gum, however the engine turned over freely and the liner isn't pitted at all. If I wanted to get it running does it just need a hone? Also the carb is completely covered in aluminum oxide what is the best method of removal?