When I made mine I used 2 cycle oil so if it gets sucked into the carb it won't hurt anything. I also put a small ball valve at the bottom of the loop. That way I can open it slowly and if the balance is way off I can quickly close it again preventing anything from getting sucked into the engine. This home made tool is very sensitive and works great. You don't need to turn the balance screw much to make a difference, good thing too since that sucker is hard to get to. I take my tank off and put it up on a shelf with a long fuel line so it is complely out of the way.

You have to adjust the mixture screws one at a time. If they don't make a difference you may have clogged passages or need a different pilot jet or you have the butterfly so far open that you are not running off the idle circuit.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!