Finally finished breaking in the new piston/liner in this .25 FSR and got a peak reading after (8) 6min heat cycles. I let it run about 30 seconds at peak without any sagging and obtained 15,550rpm using an 8x6 APC using a Jett tuned muffler, MC59 plug, and 75/25 methanol/castor fuel. I used the same fuel for all of the break-in runs. The piston seal still stinks - not any better than it was before I ran it... It starts on glow by hand easily (back flipping). I'll run some nitro through it and give it some time to finish bedding in before I dieselize it.