Stihl BR420 Starting Secrets?

Discussion in 'Mechanic and Repair' started by mcambrose, Apr 24, 2007.

  1. mcambrose

    mcambrose LawnSite Senior Member
    Posts: 510

    I bought a used BR420 that runs great when it starts. It seems to be very easy to flood. Sometimes it will start cold without any choke, so that seems to indicate good condition of the engine. I usually try to start it by giving half throttle and choking until it hits and then switching choke off. Sometimes it gets flooded. Maybe I should try without choke first. Does anyone use another procedure to start when cold that seems to minimize flooding?
     
  2. Mic_bug

    Mic_bug LawnSite Member
    from N.B. MI
    Posts: 201

    No throttle when starting...only choke til she hits.
     
  3. lawnboy dan

    lawnboy dan LawnSite Gold Member
    Posts: 3,712

    no trottle ever when starting .hot or cold
     
  4. unit40

    unit40 LawnSite Member
    Posts: 100

    Check your air cleaner, plug and spark arrester. Most units lock on full throttle to start.
     
  5. mcambrose

    mcambrose LawnSite Senior Member
    Posts: 510

    Thanks for the replies. I see that two out of two say not to use throttle when starting. I guess I learned something. That is why I come to this site. Have a nice day.
     
  6. Nukeman 7

    Nukeman 7 LawnSite Member
    Posts: 7

    :usflag: All Stihl 2 cycle engines flood easily due to the design of the carburetor. If you check the owner's manual, it provides very specific starting instructions. Always use 89 octane gas, set the choke when the engine is cold and leave the throttle in the fully shut (i.e., released) position. Pull the starter cord rapidly until you hear the engine "pop" as it attempts to start. As soon as you hear the first "pop", you must open the choke or it will flood. It should start on the next tug. My dealer was very emphatic about using this technique when I purchased my BR 320. I have not have any problems in eight years of using the blower. Also, you will see a significant improvement in performance if you remove the spark arrester screen from the muffler outlet and use a 50:1 mix of Mobil 1 Racing 2T synthetic oil. It is marketed for 2 cycle motorcycle engines and air-cooled lawn equipment. You should be able to locate it an AutoZone store for ~$8 a quart.
     
  7. mcambrose

    mcambrose LawnSite Senior Member
    Posts: 510

    Thanks for the detailed information.
     

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