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jd 757 problems

Discussion in 'Mechanic and Repair' started by copeblk, Sep 2, 2006.

  1. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    have you checked for water in the carb bowl? If there is none then remove the carb, take it apart, spray with brakleen or equal, blow it all out with compressed air, put it all back, change fuel filter, see what happens. I suspect the main jet passageways are plugged somewhat.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Sorry, Had to run some errands......
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Hmmm, Does this air filter look like yours ?

    FH 721 Air Filter.jpg
  4. shop22

    shop22 LawnSite Member
    Messages: 134

    make sure your air filter is for the proper carb. kawi makes one for internally and externally vented and they look identical and if you don't have the right one engine will get choked out. I've had to switch several on customer's machines this year.
  5. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    The pic. applies to the above ^^^^^^^

    Copeblk, If your filter looks like this I'm sure shop22 will post how to identify which carb. you have and the Kawasaki part number for the proper filter. :waving:
  6. DLCS

    DLCS LawnSite Platinum Member
    Messages: 4,386

    His air filter will be the large round kind. I'm betting money its only running on one cylinder. :confused:
  7. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    You may be right DLCS, But I looked at the fact he said it idled fine and ran fine at high speed thus discounting running on one cylinder because a twin will not do this, There would be a definite change in engine speed and sound.

    As for the air filter I have no way to tell which style he has other than what Kawasaki shows. If it is the one posted,The wrong filter installed will indeed let the engine run properly for a short period of time until it collects a small amount of dirt THEN cause a rich burn lack of power under load situation. :waving:
  8. dlm17

    dlm17 LawnSite Member
    Messages: 102

    rob, jd designed its own filter about 10 inches round and as we know i have a little exp with 757s these filters clog easy but will just seem like its losing power but not bogging, with my recent problem could it have overheated and losing power under load valve or lost compression
  9. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    If I read your question correct, Yes the exhaust valve could have overheated warping the valve head or burning the seat area and drop compression to a extent. Kawasaki shows no replacement valve guide or seat so if this were the case a new head would be required if the seat area could not be re-ground.
  10. dlm17

    dlm17 LawnSite Member
    Messages: 102

    rob, cope said it happened suddenly which is how mine failed so i was saying that maybe overheating could have caused a problem i dont have it here but i think jd had a service bulliten saying that loss of power was a symptom of overheating, just a thought

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