This Husky trimmer is a commercial model that a friend of mine bought new about eight or so years ago. Last summer it quit working so he took it to a local small engine repair shop and they said it needed a new top end, but they were not interested in doing the work. So he asked me to take a look at it. When we did a quick once-over of the unit it was clear there was something wrong as there was very little compression. So we pulled the top end off, which came apart easily, and sure enough the piston and cylinder were severely scored and the ring was fused into the ring groove. I suspect the unit overheated, probably due to a lubrication-related failure. The spark plug, which by the way was quite new, didn’t show signs of significant overheating due to a mixture-related issue, though it was a touch on the white side. As I don’t know what the previous plug looked like, this leads me to the heat/lubrication theory.
In any event, given it’s an expensive unit and in very good condition, the owner elected to replace the top end, so we order a complete top end kit. Once we have all the parts together, we’ll fix ‘er up and post a follow up.
There’s an attached YouTube video link below that shows more detail than I can easily describe.