This is great info.  I was not aware there were crank changes, etc. on the factory 170 CDI.  The 175, yes, I did notice different parts. I have other YS engines and love all of them.  This is the first 170 and as with all of them, they have their traits. Learning those traits = a joy to run.  I'll try the 30% Heli and it sounds like the conversion Central Hobbies has is worth it.