Small Engines (Lawn Mowers, etc.): 18.5 HP Briggs & Stratton engine surges except at high speeds, briggs stratton engine, briggs stratton

Question
On 11/5/2008, you suggested "Have you cleaned the high speed fuel circuit.  There is a bolt/screw on most of the L head twin carbs that you can remove without dis-assembling the entire carb.  Removing the bolt/screw on the located on the lower half of the carb will provide access to the high speed jet.  Blowing air from an air compressor through the high speed jet will often solve the surging problem."  My engine is an 18.5 HP Briggs & Stratton Twin II I/C, Model 42A707, Type 1237 01, Code 9501135B.  I assume it is an L head twin and has the bolt/screw you mention.  I know you said completely dis-assembling and cleaning the carb is the preferred repair method, but I'd like to use the simplest method first. I don't want to do any damage with the compressed air, so what psi would you use to clean the high speed jet?

Answer
40 PSI is plenty.  About the only damage you can do with too much pressure (PSI) is blow the inlet needle seat out of the carb.  Not too worry as they are cheap and easy to replace.

Those carbs are pretty simple but it helps to take pictures as you dis-assemble so you know how to put it back together.

Eric