After getting mine out of the plane...
it has really bad burns down the back of the head... it must have been lean
the head bolts were pretty lose also... i just tighted them up about two runs ago
wonder why they were coming lose? maybe need lock tight
the piston also looks very burned

I was tuning it with a tach... max rpms then back of 500 sometime 300..

strange ... but it's over now.. the 55ax is in... along with a new futaba fast 7ch system... curious to test it
break in the new one tomorrow

Ron