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Kawi FC420V questions

Discussion in 'Mechanic and Repair' started by scaghydro, Oct 3, 2007.

  1. scaghydro

    scaghydro LawnSite Member
    Messages: 5

    Hey, all

    Im new to the forum and need help with my SCAG 52" Hydraulic walk behind. It has a Kawi FC420V recoil start motor.

    It has been having trouble starting lately, backfiring through the carb and exhaust...so I took the carb apart, cleaned it with carb cleaner and put it back on...still same problem. Adjusted the valves (.006?) at tdc on compression, still same problem. changed the fuel filter..plug....air filter...still same problem.

    The grass is very long!

    I also adjusted the air gap on the ignition module and taped any worn areas on the wires leading to it...

    Once it is running (If I keep at it long enough, 3 or 4 sessions of recoil he!!) it runs like a champ.

    It sounds like a fuel delivery problem, but theres the backfiring issue which sounds like the valves.....but then, once its running its fine?

    I have gone so far as to take the head off and clean the carbon, etc...but all looks better than I thought. Should I take to valves out (dont know how) and clean them? I think the head bolt torque is 38 lb/ft. for putting it back together....

    I really should get a manual!

    Any help would be greatly appreciated!

    thanks very much

  2. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Have you changed the spark plug?
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    You have set the valves properly and to the right spec,

    Not very common on belt drive units but could happen, Have you checked for a partially sheared flywheel key ?

    If you use the search feature on top of this forum you can find a link to a PDF service manual I posted a while back (can't post them any longer).

    BTW, Welcome to LawnSite !
  4. scaghydro

    scaghydro LawnSite Member
    Messages: 5

    Yes, new plug but I have not tried it since I took the head off.....


  5. scaghydro

    scaghydro LawnSite Member
    Messages: 5

    Hi, Restrorob,

    I checked the clearances 3 times thinking I must be doing something wrong, but they are right on.

    I have not checked for a partially sheared flywheel key yet, will do that tonight....

    Ill also check out the PDF link you mentioned....should help quite a bit!

    thanks very much, Ill let you know how it goes!

  6. scaghydro

    scaghydro LawnSite Member
    Messages: 5

    Thanks, Restrorob for your guidance in fixing my 420V. I have the head back on, valves adjusted etc.

    I moved on to the electrical system and found the coil to check out but the control unit is testing a bit low ( 300ohms on the 1x for the case and 35ohms on 1x for the terminal. This seem closer to the control unit on the 460V manual you posted a while ago, but I used the values you posted not long ago for the 420V....) for the 420V (recoil start) The unit has BM11 stamped on it, if this helps at all....I think I will try to see what kind of spark I get as I replaced the plug, plug wire and terminal end.....

    Am I on the right track?

    thanks again for your help!

  7. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    It appears you are, That would have been the next step.

    If the igniter is testing low then it could in fact be firing at the wrong time causing the back-firing.
  8. scaghydro

    scaghydro LawnSite Member
    Messages: 5

    Well it runs better than it ever has in its life.

    Just to recap....changed the head gasket, plug, plug wire, fuel filter, oil filter, oil, air filter and element, cleaned the carb, painted the muffler and cleaned it from stem to stern.

    I ended up getting a new multi tester and decided to check the wiring while I was at it. All the grounds were good, safety switches good, key switch.......bad!!!!!. Well, when I say bad, I mean intermittent. (just like the starting problems I was having!!!!!)

    Even if the easy to check and simple little key switch WAS the problem all along, I have learned some valuable troubleshooting tips. Preventive maintenance is the way to go!

    Thanks for all your help, especially restrorob. It started on the first pull with very little gas in the carb and an empty fuel filter!!!


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