'96 Merc 25 doesn't idle.

[Alex from GA]

It's a manual start tiller controlled 2 stroke. I've been working on this engine for over a year. It's been to 3 shops to no avail. Last year I took it apart and found scored pistons and walls when it first started fouling plugs and not idleing. I had it bored and installed new pistons, gaskets and seals. Ran it on double oil for the first tank of gas. I've rebuilt the carburetor several times with new kits. I bought a used carburetor and rebuilt it thinking there was a porus casting or something. The last shop I brought it to put on the advance linkage from another engine as mine didn't have one. The timing wasn't adjustable. Does anyone know the timing at idle and at high RPM? Today was the first day it didn't rain for a while so I worked on it. It'll run at mid and high RPM but when I try to idle it down it seems to fart every once in a while then when I get it down low enough to shift it'll die. The bottom plug is much darker and wetter than the upper one. Can anyone help. Thanks, Alex

[carogator]

sounds as if you are trying to run it lean. that will destroy pistons like you did. it will also let it not idle.