I posted this in the Puppeteer thread but here it is again. On the last of six flights the other day, my Saito 56 which had been running absolutely beautifully sagged and died just before take-off. And I wasn't able to get it started again. No, that's not quite right. It always starts right up. But always dies at full throttle.

The next day I had a new fresh can of fuel (which I had suspected might be part of the problem) but it's the same thing. Here are the symptoms: 1) idles a bit higher than usual 2) good revs at middle throttle 3) sags considerably in the top 1/3 of the throttle and then dies 4) after even a short run engine seems hotter than normal and there's some smoke coming off the muffler (which I don't usually see). All this suggests to me that maybe it's running lean, but how does an engine suddenly from one flight to the next, runs lean when it's been flying beautifully all day?