ORIGINAL: 72
You must have bought a Friday engine because I've had one flying for 2 years now with zero problems. I have used an Rcexel ignition and an NGK plug since the start. No deadsticks, no midrange burble, just solid running. Currently using Redline synth at 70:1
I have wandered if maybe it is WHO I bought the engine from that makes the difference. The seller claimed to have parts in stock and other claims. The sad part is He at that time did not carry parts for the Crrc-pro 50cc engine. After about 2 months of waiting for him (the person I bought this one from ) His user name here on rcu, to get the parts, and after having to rebuild the engine 2 times, I finally got it lined out and was able to get it broke in and fly the plane.
The bad part is my plane was damaged becouse of the dead sticks, and dealing with this seller has been a nightmare. The Crrc-pro engines are good engines, I still have 2 of them. I even sell them out of my shop now. But I have learned to never buy anything from the person I bought this one from, , it will be a nightmare!!