I had the same problem with my Honda Powered MTD. It was returned to the seller and replaced with another brand. I wouldn't be running it with the choke partly closed. Push the choke return lever manually to open the choke after the engine starts so you're not running the engine too rich.

It seems to be a known problem with the GC engines, a Honda expert should be along shortly with more info on what the permanent fix is.

I have the same issue with my 1 year old Troy-Bilt mower with Honda engine. It's under warranty, so I'll let you know how they fix it.

Not sure if we all have the same mower but we have found a solution for Troy-Bilt w/ Honda Motor - 21 ' Rotary Mower purchased last year at Lowes.

The response from Troy-Bilt was contact Honda which we did. There is a Service Bulletin 38 that addresses these mowers purchased at Lowes and they will replace the carborator at a local Dealer. If you go to their website at Honda they will give you a local manufactur to call and they will give you a local service center in your area.

Hope this helps some of you.

here was the response from Troy-Bilt:
Response (Corey B.) 04/16/2008 10:57 AM
We have provided a few links to answers on our website that may pertain to this discussion. Please read the information at the links we have provided.

Title: Engine Support - Technical Support, Parts, Manuals and Warranty
URL: http://troybilt.custhelp.com/cgi-bin/troybilt.cfg/php/enduser/std_adp.php?p_faqid=204&p_created=1030395289
Engines carry a separate warranty provided by the engine manufacturer (see warranty). Please utilize the engine manufacturer contact information provided at the link below to contact the engine manufacturer regarding engine technical assistance, order engine operators and technical manuals or to arrange for engine warranty service.

The engine manufacturer is responsible for all engine related issues with regards to performance, power-rating, specifications, warranty and service. Please refer to the engine manufacturer's Owners/Operators manual, packed separately with your unit, for more information.

Here is a link that might be useful: Troybilt response

I was working on the same mower for a friend and found the red plastic housing was interfering with the choke returning to its at rest position. I trimmed the inside plastic that surrounds the choke mechanism and immediatly it began to work properly. Late reply , but the mower runs great now

I have the same mower but my problem is that when I put the choke lever into the start position ,it stays until I squeeze the safety handle to start it. Once I squeeze engine brake handle the choke automatically goes back to the run position instead of staying on choke. Any ideas? Thank You.

hi, post #7 might help. i'm sure i've run across videos on you tube

http://www.mytractorforum.com/155-walk-behind-mowers/545954-honda-gcv160-auto-return-choke.html