I have read this chain with interest being on my third TT54 4s. I have never had any problem with he carberettor of idling adjustment. my problem has been with part 24 in the parts list - the spring hold collars. On each of my engines these collars have shattered. I have replaced them (£5 per pair) but they have shattered again. With the first engine I eventually replaced the valves, valvel springs, the spring retainer sets and hold collars but the result was teh same. I therefore decided to replace the engine and spent a great deal of careful time running it in accordance with the instructions but withing a month the engine went pop in the air (fortunately I safely got the model back down) but this time I resisted the temptation to take the rocker cover off and look. I took the engine back to the model shop - showing its near pristine condtion and between them and TT they decided to replace it. Since the symptoms were identical (the engine going pop under full power and then total loss of compression) I am certain that is was the collars again. However the message back from TT was they did not know what the problem was and they therefore replaced it.
I returned home once again a happy man an carefull re-installed the gleaming new engine. First off was to run it in - again great care, best 4s 20% oil fuel, low revs, making sure the mixture was rich (so much so that I had to keep the glow lead on). A total of 45 minutes running - then off to the flying field and first flight was fantastic (apart from pilot effor landing which removed the undercarriage. Back home replace undercarriage and a week later back to the field. 3rd flight - pop successful but dodgy landing and yes off course no compression. this time I did take the rocker cover off and yes once again there are pieces of shatterd collar. Only the inlet valve had gone completely but the exhaust valve collar came out in two seperate bits. Before I take the engine back to the model shop again has anyone else experienced anything like this and got any ideas if I am doing anything wrong.