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eric_2007

honda hs621 snowblower

eric_2007
14 years ago

I have a honda hs621 snowblower that a bought used from a private person as is for a $180 since it wouldnt start and assumed it would be a easy fix. I drained the fuel tank and carb as well as clean the jets in the carb assembly. However the issue is now it starts very easy in one pull with choke. At half choke it runs rough with pop noise and yellow flame back fire every few seconds. At off choke the engine stalls all together. I checked over the carb jets twice including the one under the plastic plug on the top of the carb, fuel flow from fuel line and linkage for binding however did not correct the issue. turning the adjusting screw on the carb body did not help either. I also tried letting the engine warm up for 10 minutes at full choke as well as adding sea foam however still did the backfire and rough idle at half choke then drops dead at no choke. I assume the correction is to replace the carb assembly however before i invest $70 in the carb i want to verify with people out here that you dont feel its an issue such as leaking gasket or valve issue.

thank you

Comments (6)

  • tomplum
    14 years ago

    I would say that you have a good handle on things. If it ran for 10 minutes w/ the choke- figures to be carb related. The more critical part of the carb is the main nozzle up inside the stem where the bowl nut threads into. I think these are like the mowers that have a slotted thread out- that you unscrew and kind of shake out the stem. Then above that is the longer nozzle which should fall out too. Congrats on your purchase!

  • eric_2007
    Original Author
    14 years ago

    The nozzle is a 2 piece type where the lower jet part theads in the carb body and the main nozzle goes to the air intake. I cleaned all the tiny holes in the main nozzle with compressed air and can see light the holes as well as though the center of the nozzle and jet. My concern is investing $70 in a new carb only to have the same problem continue on. I know sometimes backfire flames though muffler can be valve issues but im assuming its a carb problem since the choke postion directly effects engine preformance? Also do you feel this type of snowblower is worth investing money into? Overall its in very good condtion so with original cost, carb assembly and new scraper im looking at about $275 to make this machine in dependable working condtion.
    thank you again

  • tomplum
    14 years ago

    I would think it highly unlikely that there would be a valve issue if it runs w/o backfire with the choke on. AT least that's how I'm understanding you. Sure, an OHV can be more prone to valve sticking after setting due to the light valve spring tension in part. Usually Seafoam will clear that up or one can use jet spray carb cleaner (a small amount at a time shot in the venturi as the machine is running) to remove varnish deposits.

  • ironbrigade
    13 years ago

    I know this post is a old one but I just had that same problem with my Honda 621, which I had bought new. I had also cleaned out the jets with carburator cleaner and compressed air and it still would cut out under a load and backfire. So I pulled the bowl off again and unscrewed the main jet up inside the tube to see if I could see any odstruction but it looked clear. So I used a blow torch tip cleaner with carurator cleaner and found the jet had some sort of build-up in it. So I cleaned it out well being carefull not to take any new metal and put things back together and it ran perfect. I did notice a white powdery subtance on the bottom of the bowl that I think was responsible for the problem. I think we can thank alcohol in our fuel for that.

  • ewalk
    13 years ago

    Iron: Yep you are correct ethanol is the basic cause . Use Stabil during storage and a fuel cleaner / conditioner annually to prevent recurrence issues . :)

  • ctbsdad_aol_com
    13 years ago

    How do you hook up the throttle return spring on a hs621 honda snowthrower