I will make a suggestion to you.

Get a tach and use that to set up your engine. Due to the differences in sound, there are very few people who can set up a 4 stroke properly without a tach. A $20 investment is cheap compared to possibly ruining a $300 engine.

Once the engine is properly set up you should not have to touch the low end again, and the high speed needle should not need any more than a 1/4 turn to compensate for the differences in temperature and humidity.

FWIW - If a 4 stroke engine is not "making" smoke at ALL engine speeds, there is a very good chance it is being run too lean.

I am not familiar with the plane, but if it is cowled or partially cowled, run a piece of tubing from the vent nipple to outside the plane to keep the oil residue out of the engine compartment. The vent nipple is the nipple on the bottom of the engine about 1/2 way between the prop and the crankcase.