Originally Posted by profmb
I would like to add my experience, because I have had both engines. The FG20 was wholly unreilable. MacGregor here in the UK replaced the ignition unit twice and the carb 3 times. It was so diificult to tune and from one day to the next the needle settings would vary a lot. I had loads of dead sticks and ruined two aircraft because of it. I eventually destroyed it with a headlong dive into tarmac when the elevators detached themselves - I was not at all sorry to see it go...
When the FG 21 came out I was full of optimism - the RCEXEL ignition unit was clearly much better - BUT the carb is still crap in my opinion. As before it will not hold a setting between one session and the next. I tune it on the ground - have it running on idle for 5 minutes - wack open the throttle and get 8500 revs tuned back from 9200. Yet in the air it will cut out without warning. Some might say it is over heating - but this is flying without a cowl. In the cowl it overheats all the time. I have built in cooling tubing to direct air directly over the engine and generous air extract - but still it over heated.
So I fly it with no cowl - but it still makes no difference. What I have also noticed is that when I lean the engine to find peak revs I can then make the mix richer but even half a turn or more of the needle valve and it is still running at its peak! I have to close and open the throttle to get the carb to take the new setting. Quite stupid. This is a relatively new engine, and I have filters in the tank and the fuel line and I filter the fuel in my dispenser.
Today I had yet another dead stick and ripped the undercarriage out. So that it is it - I have wasted so much time on it - it will now sit on shelf to remind me never to buy one of these little engines again. This is such a pity because the four stroke sound is so sweet. I have two FG30's and an FG57 and I have never had any grief from them. So my advice is to stay well clear of the FG20 and FG21.
Any update on how things are going on now with your FG-21?
It's quite confusing to notice you have had such a bad luck with the FG-21 while some others have found the engine to be reliable. Are you sure you haven't overpropped it?
CH Ignition has experimented the Zama carb in conjunction with the FG-21 with good luck. Just for your consideration.
Btw. why do you think you are luckier with the FG-30?