Originally Posted by
SkarTisu
jdeadman - I think that as soon as you either remove the head button, piston/sleeve, or con rod, you need to go through the break-in process all over again (or at least some period of easy running) to allow the moving parts to settle in again.
My personal threshold for temps is 300, not 250. There are some engines out there that don't start making really good power until 250+ degrees. I read somewhere a while back that 320 degrees is where the seals and nylon bearing cages start to deteriorate due to heat.
I use a heat gun and tin foil on my engines and idle them for one tank on the box somewhere around 200 degrees, then start driving them easily for 4-5 tanks after that, again somewhere around 200 degrees. After that, start working on race tune.
There is no need to re-break in an engine after disassembling it. I do it to all of my engines every couple gallons. That way I can inspect them, and I know for sure, nothing is wrong with them. It is also a very good way to tell if your tune is good, and if you are running quality fuel.
I personally agree with JAZ. 250*F is my temp limit when it comes to nitro engines.