Re: burned piston
so...a three cyliner with three carbs does not get fed its fuel mixture soley from a SPECIFIC carb??
do all the carbs dump into a "chamber" and supply all cylinders equally??
I had thought that each carb basically fed a specific cylinder....
is that not true???
bob
true far as I know, some 3 cyl's might use a common single carb.
Clogged carb jets or air leak are the common culprits.
What was the compression reading before you tore into it?
That would tell you a lot.
A loose sparkplug can be a problem, had that happen to me.
Air leaks cause over-lean running, thats the same as an over advanced ignition , then pre-ignition starts and the combustion chamber goes over the melting point of alum. Whats that, 1200degs? Not much.
If you can't track down the cause use an infra red thermometer to ensure the lower cyl is actually firing after rebuilding engine and carbs.
I would re-plumb the whole system.