Just learning to fly and I have got to the stage of doing basic circuits, Noticed today when coming back into the hover from forward flight the engine sounded very different. Instead of its normal note it gurgled a little, but still maintained higher than usual revs.

The engine is a TT36 and has had 1 galleon of fuel through it. A new fuel was being used today it is a mix that has no castor oil in it but is fully synthetic, still the same nitro content however of 10%.

Today the weather was exceptionally hot and the engine seemed hotter than usual, but it may be the weather.

The engine response is still good when opening the throttle maybe a bit too good. (Sounding a bit lean)

There is some smoke indicating it is getting good lubrication in the hover and forward flight, but not a lot of evidence of oil residue on the heli from the exhaust.

I think the slow running mixture is a little lean and I am going to richen it a bit, but before doing so interested to know what you heli experts think. Getting it wrong could initiate an expensive trip to the hobby store.

Thanks for the help