Since getting into the hobby some 7 years ago, I've flown YS exclusively. I now have a few Moki's but I have accumulated 5 Ys engines. I continue to hear about difficulties and it kind a surprises me since I find them to be the most user friendly and powerful engines. I'm not lying when I say I have never had a ys flame out on my in all those years.

A few of the things that I've found to be necessary when running YS are as follows:

1) Don't touch the regulator - it should be flush with the case per the factory.

2) OS F plug

3) Rigid fuel tank - I had huge a wierd problems with flexible tanks. They just blow up like balloons

4) Adjust high end using a tach then back of 200 - 300 rpm.

5) Break in only by running one tank on the ground. More than this can cause the engine to over heat.

6) one low end is adjusted - adjust idle so that it hits 2000rpm.

7) 20/20 fuel

Maybe I've been lucky but I have to say I really like these engines and think they are worth the extra money.

I posted this to help and in no way to undermine the problems you have been experiencing.

Mike