You are reading a single comment by @MrE and its replies.
Click here to read the full conversation.
-
I'd still look at the carb first - quicker and easier, fewer gaskets, fewer tools, and if you find sludge or rust particles you've probably nailed the cause. Removing the head would be next (assuming you can't see anything through the plug hole or exhaust port) knowing what you find will be more likely to be symptoms than a cause.
http://www.smellofdeath.com/lloydy/piston_diag_guide.htm and similar (I know, not a Vespa, but similar engineering) might help when peering down dark holes?
You can always blame the ethanol - it used to be quite the thing on NACC runs to blame E5 for all forms of breakdown...
MrE
OK. Thanks all. May pop the top off and take some pics, post them here, see what people think.