Small Engines (Lawn Mowers, etc.): Honda Snowblower Idle

Question
Hi, Eric.

Have a Honda HS520AS and was wondering what the idle is suppose to be.

Purchased this snow blower last month and it came with a full tank of fuel.

I thought it was idling fast, it was loud and has what I thought was excessive vibration. The Honda dealer looked at it and they stated it was normal.  

I have a small tach / hour meter and I hooked it up to the snowblower's spark plug wire to see what the idle was, it was 3600rpms, according to what I can find on the net that is the max this engine is suppose to be at. When I checked the idle it was 20 degrees out and was cold.

A few days later I poured some seafoam in the gas tank, just as a precaution since I didn't know how long the fuel had been in the tank, since I had heard that these Honda carbs are very touchy when it comes to fuel.

After I poured the seafoam in I started it and seen a little white smoke. I hooked up the tach/hour meter to the snowblowers spark plug wire again and it showed the idle at about 2000-2200rpms, it seemed to be quieter and less vibration. The temperature was 62 degrees out, 40 more degrees than when I previously checked it.

Did the seafoam have that much effect on the idle? Was there maybe something in the carb (varnish or little dirt? Did the temperature have something to do with the idle? I read online in a few places that the temperature has an effect on the way these engines run, because the air is more or less dense.

What is your opinion?

I cant find anything on the idle for the Honda GCV160 engine, except; Net Power Output* 4.6 HP (3.4 kW) @ 3600 rpm, Net Torque; 6.9 lb-ft (9.4 Nm) @ 2500 rpm.  

http://m.engines.honda.com/models/model-detail/gc160

Thanks, Eric for your time.

Answer
Idle should be in the range of 800-1200 RPM...average for many of today's engines.  Full speed not exceed 3600 RPM, but would be better to run at 3000 RPM...very common for small engines.  Max 3600 is important for 2 pole generators which is why manufactures typically design to a max 3600 RPM.  More RPM usually equals faster engine wear...heat, lubrication...

The Sea Form and temperature should not have had that much of in impact on the RPM.  Was the SB new or used?  I can't recall any small engine, motorcycle, small outboard that ever idled at 2200 RPM at operating temp...when the engine is warm.

Let me know if the SB is new.
Eric