Small Engines (Lawn Mowers, etc.): hondaht3818lawnmower, honda ht3813, speed circuit

Question
I have a honda ht3813 lawn mower i'am having problems with. The engine starts and run good but when the blade clutch is engaged and the governer opens up the engine seems to flood out and looses power. If i hold the govnerner to keep it from going full open it will come up to full power.Do you have a solution for this problem? Where can i get a repair manual for this mower?

Answer
Did the problem start suddenly or has the mower sat a while?  What is suppose to happen, when you engage the blade, is the extra engine load causes the governor to pull the throttle open to allow the carburetor to provide more fuel from the carburetor high speed circuit.

Are youholding the governor/carb butterfly closed to keep the engine running?  Is the engine running too rich?  Is the spark plug dip black?

Eric