Please help here. New to gas engines. I have a Poulan 33cc and I wanted to know if there is a rule of thumb for enrichening the high speed needle from max rpm. In other words, when I lean the engine to get max rpm, how many rpm's do I reduce using the high speed needle for the best longevity of my engine? I don't want to burn the engine up. Thanks in advance. Jeff

Most here use 1/8 turn rich.

I've never used a tach to set my needles. I normally start by getting both needles close, but defintely rich. I then adjust the low needle a lean as possible a still get good acceleration when I jam the stick. The low needle will lean more, but the engine will gag on acceleration. I then lean the high needle until I find the lean drop-off point, then richen it back about 1/4-3/8 a turn. It took longer to type this than actually do it! I don't claim to be an expert, but I haven't burnt or overheated a gas burner in 15 year of flying them either..

Thanks for your help!!!

One additional rule of thumb> the engine should never slow on extended vertical flight .
this can be tough on setups which are underpowered but the prop load INCREASES as the model speed DECREASES and this all shows up as increased internal heat.
I am assuming full throttle during this example.
The engine sees this the same way as it would if held at full throttle on the ground and run wide open.
This is a maximum load situation.
Max load means max heating potential.
So use your ear for correct settings if you can.
Avoid adjustments which allow a cold engine to slow up after a moment at full throttle.