Too rich of a setting will result in low power just as quick as to lean---ideally you should set the mixer based on a electronically controlled sniffer in the exhaust. I never had a "sniffer" but always checked out pretty good against the sniffer based on holding a steady load on the engine and maximizing the rpm by adjusting the load screw (big screw)----this is alot easier done with an auto transmission than standard transmission and clutch (with a standard transmission you will need someone to either drive pulling a load or ride the clutch for you----but keep a very steady load so that you can tell what your adjustments are doing). Use a handleld tachometer if available.

The idle setting will not have much effect on total power----best way to set idle, again is to maximize rpm while adjusting idle screw (small screw). When rpm is maximized---engine should start imediately with little to no throttle opening.

As stated in one of the above postings---you should not have any gas passing through the regulator without the engine running. Vacuum cracks the diaphram in the regulator (vaporizer) once the engine is running----a leaking regulator will result in excess gas flow (flooding) and thereby preventing you from ever getting a true setting. With everything off---you should not be able to smell any gas. I have had them leaking to the point that you could hear, smell and see the leakage.

I have run both 225 and 425 mixers----I ran the 225 on a 327 V8 Chevrolet in a Massey Ferguson combine----the 225 may still be too large for your small engine application??? Ran 425 in larger applications.

I always found that lack of air was the biggest limiting factor effecting power on the L-P setups (running to rich, or flooding)----use a big volume air cleaner and keep it clean so that you can keep plenty of air coming to the intake.

Just noticed your question----passing on a few of my thoughts. Good Luck!!

Delta Dirt