Hi. I'm trying to get in the hobby again, and I have a problem that could use your knowledge in solving.

The problem is I have an 2-stroke engine that has been mothballed some 6 years ago. Hasn't run since then. That in it self isn't much of a problem provided you cleaned it that last time it was used. Well.. herein lays the problem.. I didn't. It's all sticky inside and out, and it doesn't seem to compress...

Well, I'm trying to get it clean, and i'm currently using petrol, but it doesn't seem to be working.. any ideas?

Thanks.

Use fuel only, inside and out. With a stiff brush and some wrist grease, soak it, and brush, and soak, and brush, till you got all goo off.
The inside, just soak it until the engine is loose, gently apply rotation torque pressure until it budges. Do not force anything. Heating with a paint stripper helps solving the dried oil into the new fuel.
The carb fuel passages should be cleaned in fuel as well, unless you want to experience sudden flame-outs by undissolved flakes lodginging between needle and seat.

This is worst when the engine has been run on castor fuel. Wake her up right, and you will do well.

If all else fails, use the crock pot method, and simmer the engine for a while in anti-freeze fluid. Do not use your wifes cooking pot for this. AF is a sweet tasting poison you do not want to ingest.