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Thread: motor recarb or replacement advice

  1. #11
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    Thud,
    I'd love to do the carb work but fact is I'm pretty bad at this kind of thing and really want to use my boat. I can certainly check the compression if I could find a socket that could fit into those tight spaces. I can't find anything to fit. Ideas?
    G3PO

  2. #12
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    sounds like you need what is called a thin wall socket and maybe universal at the and of it good luck
    team member

    of the 2011 winners of the c.d.c. lake hartwell fall fest

  3. #13
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    What are the symptoms?

    I helped a guy do a 'leak down' test on an Airplane engine. I don't think it was worth the time it took.
    In the end, if you don't do some other tests you still wont know what's leaking down.

    Compression down to 50 Lbs says there is something wrong. All cylinders equal is saying there is nothing catastrophic wrong. As in a broken ring, burned valve, and other mechanical snap crackle n' Pop.

    It's not telling you the engine has not been "cooked" or overheated to the point the Rings have lost their tension. The Cam timing may have slipped. All the intake Valve lobes on the Camshaft might be worn down. The lifters may have collapsed.
    Knowing the Symptoms would help.

    To do a compression test that will tell you more than a Leak Down test:
    Warm engine,
    Plugs out,
    Throttle blocked wide open, If all the Carbs are not Wide open, or the Choke is closed the test wont mean a thing.
    Screw the test bit into each plug hole,
    Run the engine over with the starter and a fresh battery, at least three times.
    I do more and watch the gauge. It will climb to a certain spot and gain no more!

    Do that at each piston.
    Then spray or pour some engine oil down the plug hole and repeat the readings.
    Mark each reading down. Compare the "Before Oil" and "After Oil" readings.
    They should be slightly Higher with Oil.

    Any significant raise in compression is likely to be bad Rings or tapered cylinder Bores.
    Very little or No change is likely to be leaky valves or broken valve seats.
    Whatever the problem might be, it's common to all cylinders if the test results are the same. Like 50 Lbs per cylinder.

    Is it possible you ingested water and have a bunch of Bent Rods?
    Use a tool and see if the pistons come all the way to the top of the Bore.
    I just wish I could be better at fishing. Or maybe luckier!:D

  4. #14
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    Guys before yall head out doing carbs on 4 stroke you have to get a set of vacuum gauges.. these new 4 strokes have cost me money in tools. there totlly different you can not set these carbs without gauges. you can and ive done it pull them apart and get needles that will match up with 4 strokes. that way you dont hae to buy the kits..

  5. #15
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    Boatman you correct about the gauges.I paid over $600 for my honda gauges.

  6. #16
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    Yes, Multiple carbs mean a little syncing. In 53 I put a Three carb manifold on a Ford Flathead V-8. I was just a kid, but I learned quickly enough from the 'old' guys the uneven distribution principal. I thought it'd go like all git out, but it just slugged along till it go going...etc.

    What's the Symptoms?
    You have a lot of help here, but you must describe the symptoms before we can take you to the problem area.
    What do you see or feel? What took you to the Mechanics?
    I just wish I could be better at fishing. Or maybe luckier!:D

  7. #17
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    Guys,
    thanks for all the advice,
    here is what it does,

    1, pretty hard to start,
    2 darn rough for a while after it get going
    then
    3 it idles pretty well once really warmed up
    4 as i bring up the power, it stalls out on the hole shot, it just can't burn the gas.

    Now, I did get it up plane last time i went out, had to baby it but it got there, ran OK

    I hear this "pop pop" sound from the engine and the rpms drop a little each time, almost sounds like a quiet back fire

    thanks again
    G3PO

  8. #18
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    I'm no mechanic by no means, but from experience it sounds like you have a beant or probably broken rod. I had an 86 90 Merc. do the samething you are describing, the mechanic got to the problem by running it and just had to retire the motor for good the only way to fix it was a rebuild....if you need a good boat mechanic I know one in Newberry, SC

  9. #19
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    Did you notice if the Plugs were Wet, sooty, burnt blue, caked with crud, black with oil, etc.
    That Carb out of tune could make a lot of that happen. All you have to do is get one cylinder wet and the others still looking for fuel and you get 'Popping' in the exhaust. That popping is probably went fuel being ignited by a firing pulse.

    One leaking intake Valve, causing a backfire (Intake manifold Firing pulse) to "stop" the vacuam pulses to the other cylinders. Causing some of them to go without fuel, which causes the Missing which causes the Rough burning.

    When you give it the Gas for the Hole shot, one leaking intake valve will shut down the whole intake sequence.

    That would also be the reason you cannot get it up on plane.

    Timing advanced, or something loose in the ignition also might be a problem.

    At the same time, low fuel pressure, clogged jets or something in the Venturi causing the Fuel to be raw in big droplets, and not atomized will also cause Intake firing. I hate to use that word "Backfiring" but it can also blow gaskets in the intake and Carbs.

    But the whole engine problems stem from that low compression.
    I dont know enough about your engine to take this any further.

    If you cannot work on them, (my hunting partner was a Deputy Marshal. He told me the only tools he knew how to use were for Killing people!")

    Develop a friend with dirty fingers, or Pay for some troubleshooting.
    Dont replace things until you know why your doing it and know what to expect if its gonna solve the problem or make no change at all.
    I just wish I could be better at fishing. Or maybe luckier!:D

  10. #20
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    Thud
    Well the real ? is what costs might i be looking at given the various possible issues with the compression.
    Are we talking rebuilding the motor?
    thanks
    G3PO

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