I am most definitely NOT an engine expert, but have many years of meesing with them. You didn't mention how many times the engine has been run/flown, but I suspect that it may still be "breaking in. If so, it needs to be run a little rich. Many flyers, and especially rc newcomers, adjustt the needle valve for absolute maximum rpm on the ground. When the load on the propeller lessens in flight, the engine speeds up , leans out (not getting enough fuel/oil), gets hot and quits.

I haven't had a .46 LA, but I am currently operating four OS Max 40 LAs (covered in the same OS operations manual as the .46), on two twin-engine planes. Each of the engines was broken in on a sport plane, and took about 10-15 flights (two hours??) of running before they could be flown near peak rpm. On the twin I always keep the engines just slightly richer then peak.

Some things to check;
1) are you using the recommended size propeller - 11 x 7 (a smaller prop could have the engine running too fast...and lean)
2) before taxi and take off are you peforming a full throttle test with the nose vertical? hold for at least 5 secs, rpm should stay constant and about the same as when level. Decrease in rpm indicates you are too lean, while an increase indicates too rich. The greater the rpm change, the more you will adjust the needle valve setting.
3) can you feel oil coming from the exhaust (its hot so hold hyour hand a few inches behind the muffler outlet), and/or is there a visible exhaust trail behind your flying airplane? if not, you are probably too lean on the needle valve setting.
4) does the exhaust have a lot of black residue? This occurs some what while the engine is breaking in, but a lot of black indicates a lot of aluminum wear and generally indicates the fuel-air mixture is too lean.

I hope something in the above is of some help.