I need some counseling….

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    fleetwin

    US Member - 2 Years
    Replies: 3483
    Topics: 52
    #216849

    It’s hard for me to admit that an old 6hp has kicked my butt, but it surely has….
    I bought this 69 Johnson 6hp years ago, previous owner told me his kid had dumped it overboard then just hid it in the basement…. I bought the engine, it freed up pretty easily, looked as if water had only entered one combustion chamber. I pulled the intake, crank looked as if it hadn’t gotten wet at all. Don’t know what made me probe the rings, but did, and found that they were stuck from rust on one cylinder. The engine sat around my basement for years, even bought a replacement powerhead for it, along with rebuild parts for the original powerhead.
    Finally decided to stop kicking this engine around the shop and repair it this spring. I dismantled its original powerhead, replaced the rings, crank bearings, honed the cylinders, replaced all gaskets and seals (pulled exhaust cover also). While working on the powerhead, I noticed the center main crank bushing seemed worn/scored, but the crank seemed OK, so figured it would be OK this way. I ripped the gearcase apart, oil was milky, replaced clutch dog, seals and orings. And of course, it failed the pressure test, driveshaft seal surface was grooved….So ripped it all apart again and spent money for a new driveshaft. New impeller, and crank seal components. Cleaned and checked magneto, rebuilt carb.
    Should have known things weren’t going to go well when the waste oil I brought to my friend’s shop leaked all over the trunk, and the recoil rope pulled out in my hand while attempting to start this thing in his test tank…..
    Finally straightened out recoil rope and fired it up. Seemed to run OK, idled just “OK”, new rod needle bearings seemed sloppy and noisy though, my eyes and shaky hands probably messed up the tiny 30 needle bearing installation job. The engine lacked power at WOT with a 7″ prop installed while running in the tank….Thought it was running on one cylinder, but both cylinders seemed to be contributing equally when plug wires were pulled. The engine did not run rough/rich/lean at WOT, just had no power. We even installed the correct test wheel, would only turn up 3000RPM. Was totally depressed by my failure here, the ribbing from Gary and the gang didn’t help much either…. Took it home to think about what I must have done wrong.
    The only thing I could come up with was that I ignored that damaged center main bushing ignoring that it might cause a crankcase leak between the two cylinders. The mag plate was advancing fully, and the butterfly was opening fully also.
    So decided to write off my rebuild job and install the used powerhead I had bought years ago….I pulled the head and exhaust cover on the second powerhead just to check everything out, all seemed good. Cleaned up the carbon and reassembled. Please note I used the head and exhaust cover pieces from my rebuilt powerhead because they were all cleaned up, just replaced the head and exhaust cover gasket again. I confidently put this project back in Gary’s test tank, only to find it ran exactly the same way it did with my rebuilt powerhead…. Quickly condemned it again, in favor of running a 57 Fleetwin I had brought along as well…
    I had never run this engine prior to rebuilding the powerhead, ran the same way with another used powerhead (using original head and exhaust cover with new gaskets.
    Lacks power at WOT, even with correct test wheel, doesn’t run rich or lean, or rough, just lacks power (only 3000RPM with correct test wheel)..
    Pulled carb apart again, nozzle gasket is in place, has .044″ high speed jet (parts book only lists part number, not size of jet: 315140 (can’t find this part number/doesn’t list opening size)
    I had the powerhead and gasket off a few times, sure thought I would have noticed a exhaust obstruction, but saw nothing wrong.
    This gearcase does not use the shock absorber, so it is not an issued of this piece binding the gearcase
    I was worried that I had installed the wrong flywheel, might have mixed it up with a 9.5hp flywheel I had laying around, but compared the two, magnet location/keyway seemed identical. So, I guess it was a 6hp flywheel I had laying around.
    I have researched the carbs for these engines over the years, pretty much the same up to 1975. 1976 was a strange year, used a .052″ high speed jet. 1977 and newer models used a .042″ high speed jet…The high speed nozzles have different part numbers, so am wondering if someone before me messed up this carb with mismatched innards.

    Don’t know where to look next, have put it aside for awhile hoping that “aha moment” will come to me in a dream sometime. I guess next, I will try a different carb assembly, and recheck the reeds (remember I used the reeds from the original rebuild powerhead, the intake manifold casting was broken on this used powerhead). Perhaps the reeds are partially rusted/stuck closed, but this seems like a long shot, never really tried to push the reeds open, they were not rusted or corroded.

    I’m convinced I made some foolish mistake or “assssumption”, need some fresh outside thoughts here….. Was going to attach a video, but it is too large for this website, of course….
    Thanks
    Don

    • This topic was modified 1 month, 1 week ago by Avatarfleetwin.
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    billw

    US Member - 2 Years
    Replies: 1312
    Topics: 42
    #216866

    I had a Merc 200 automatic that preformed in a similar way. It had the right main jet in place, by the stamped number; but someone along the line had enlarged the HOLE with a drill, just a bit. When I finally figured that out (after a couple of YEARS) I robbed the jet out of another carb and the thing ran like the wind. Totally different engine, in terms of performance….

    Long live American manufacturing!

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    fleetwin

    US Member - 2 Years
    Replies: 3483
    Topics: 52
    #216895

    I had a Merc 200 automatic that preformed in a similar way. It had the right main jet in place, by the stamped number; but someone along the line had enlarged the HOLE with a drill, just a bit. When I finally figured that out (after a couple of YEARS) I robbed the jet out of another carb and the thing ran like the wind. Totally different engine, in terms of performance….

    That is surely a possibility, just wish there was an old cross reference sheet that described what size the original part number jet is supposed to be… I’m thinking someone messed with the carb, perhaps the main nozzle. I have another 6hp that I will eventually rob the carb assembly from… Will pull the reeds again also while the carb and recoil are off. But, for now, I need to put this aside and move on to projects I will have success with.
    And according the boss, those projects are:
    finish the trim and floor moldings on renovated kitchen
    CLEAN THE DAMN CELLAR
    etc, etc….

    Avatar
    jeff-register


    Replies: 1225
    Topics: 49
    #216896

    Don,
    Sounds like some of my builds except you get an “A” for efort!! Had the same issues with a barn build carb too.
    Take care &Make her happy,
    Jeff

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    fleetwin

    US Member - 2 Years
    Replies: 3483
    Topics: 52
    #219335

    OK, will try to post a video of the engine running….Can’t upload the file here, too big… Will try to use a link

    View post on imgur.com

    Avatar
    eviltwin


    Replies: 97
    Topics: 5
    #219401

    Are you starving for FUEL somewhere? Check all the lines, tank, pump, filter, etc…

    Avatar
    fleetwin

    US Member - 2 Years
    Replies: 3483
    Topics: 52
    #219406

    Are you starving for FUEL somewhere? Check all the lines, tank, pump, filter, etc…

    Well, surely possible…But, it didn’t respond to partial choke like it was lean, it choked out rich. It kinda runs like the mag plate is not advancing fully…Kinda like manually pushing the carb open at half throttle without advancing the timing. But, the mag plate is advancing fully, checked that again when I swapped the powerheads.
    I wish I knew more about the history of this engine…Perhaps it ran this way for the PO, and they never realized it… If not, what did I screw up to create this situation….
    I’m gonna try a different carb to rule out that possibility…

    Mumbles
    Mumbles

    Canada Member - 2 Years
    Replies: 4600
    Topics: 437
    #219426

    Link and synch is done correctly and compression is right up there? Besides the jet changes, several different cams were used to over the years.

    I’ve found when these motors lose power, it’s usually from worn out rings. Something else I’ve noticed is the 5.5 and 6 horse motors like to score pistons more than other models do. Don’t know why but they do.

    • This reply was modified 1 hour, 28 minutes ago by MumblesMumbles.
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