This is one of those "story ending with questions" postings.

First the story:

Yesterday I ran my fresh rebuild 1986 (propshaft rated - power ported yada yada) )115 inline in the driveway for a couple hours at 1000 RMP to give it a head start on break in as well as tweak and poke and prod it.

I leaned out the mixture screws just so it wouldn't load up and die out while sitting there. I **forgot* to fix them back and during the first 1-2 miles of todays break in cruise at about 2500 or so RPM (and still well in that circuit on the carbs)) my temp alarm went off.

The (factory installed) sender is imbedded in the #1 head. The leanest carb (thank Cod!) was the top one fedding #1 and #2. I killed the motor within 1/2 second of hearing the alarm and quickly got to the bottom of things and had a good rest of the day breaking it in.

Later in the afternoon I peeked at the eyebrows of 1,2, and 3 and they all looked undamaged. I have seen heat damage before though on the exhaust side of the piston ring lands on those pistons - even with undamaged eyebrows. I don't really wanna pull the exhaust divider plates to go peeking though.

I was running 20/1 at the time for break in and premium fuel and I'm glad of both!

The motor *seems* to run unharmed.

My questions:

How effective (in general) are those over-temp sensors?
Are they deep enough in the head to catch combustion chamber overheat quickly?
What say ye all about my pistons? Are they probably OK??

I'm looking for a little reasurance that I don't have to scatter it to go peeking with only 3 hours total on it.

Thanks,


-W