Temp: 14C/57F
Fuel: Rapicon HLS 15%

APC 12.25x3.75 - 10600
APC 11x7 - 10300
APC 12x6 - 9600
APC 13x4W - 9200
APC 13x6 - 9000
RAM 13x6 - 8900
APC 12x8 - 8400

Seems a little low, my Enya 60 turns an APC 12X8 to 9200. Perhaps with a little more break in, my Enya is very "experienced".

I agree, the numbers seem a bit low. This is after ~3 gallons. I'll just pretend it's a 52.

Iwould check the usual suspects. Cam timing, valve lash ,glow plug heat range.

jeffie8696; Thank you for the suggestions! Cam timing is correct, and the glow plug is an OS F. The valves might be on the loose side, but I'm not sure. A .0015" feeler gauge will pass freely, a .004" will pass with some friction. I set the valve clearances yesterday before I ran the engine. The valves seem to seal better after I adjusted them.

I'll try a fresh bottle of fuel and see if that changes anything.

You seem to have covered the basics. Yea maybe a different jug of fuel will help.

My ASP FS61AR in a Thunder Tiger Ready

APC 12x6 propeller: 10,200 rpm.
Powermaster fuel: 15% nitro & 18% oil
Elevation: 3000 ft
Temp: about 60 degrees F.
Glow plug: OS F

Engine has a problem with mid-range. Runs rich between 1/4 and 1/2 throttle. Anyone else have this issue?

Mine does that too! It will idle nicely at 2000 rpm and run great at full throttle, but half throttle is very rich. It won't quit in the air, but I'm not comfortable flying the airplane with it. Rpms go up and down, and it sounds like it is drowning in fuel. Around 2/3 throttle rpms increase a lot, and it runs smoothly from 2/3 to full. I haven't been able to figure out what causes this problem. My guess is that the low speed needle gives a leaner fuel mix at idle than at half throttle. If I could adjust the hole in the spraybar, the problem could probably be fixed, but I'm not a very good engine surgeon.

Hi!
If rpm alters at low setting the low speed needle is set too lean!

jaka; setting the low speed needle richer makes the problem worse. The rough sound and amount of smoke also indicate that it is running too rich in the midrange. The more I lean the low speed needle, the better it runs in the midrange. When leaning the low speed needle, I get to a point where the mixture at idle is so lean that it won't pick up rpm when I hit the throttle, but the midrange is still too rich. It seems impossible to get both the idle mixture and the half-throttle mixture correct at the same time. All suggestions are welcome.