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  1. Member
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    Jul 2013
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    #21
    Great info as always guys

    One more question, it was indicated that the power head does not need to come off. And just remove the drive shaft housing??? I assume I need to support the engine while removing the drive housing??

  2. Member
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    Jun 2004
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    Flowery Branch, Ga.
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    #22
    While it's off, a good time to put a 200 tuner on it, and gain a little top end power. The XR6 tuner is long and restrictive.

  3. Member
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    Apr 2012
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    south australia
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    #23
    Power head needs to come off and you will probably find the tuner is cracked due to hanging on one stud for awhile before falling off, but you could be lucky.

    I would stay with the longer tuner if it's a fishing motor as the shorter tuner will lose bottom end and be more acceptable to fouling plugs and lower RPM.

    Motor will be a lot quieter when it's fixed...

  4. Member
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    #24
    I have to disagree. The longer tuner keeps the exhaust bottled up making it more likely to fowl plugs than a shorter tuner. With the shorter tuner, the motor will free up quicker many times helping holeshot. The tuner on an outboard is not like the tuner on a bike. It's more like a collector. The exhaust ports are less than an inch long, dumping into the collector area. The long tuner was used by Mercury to help restrict the power keeping it in the legal 150 */- 10% range. (Unless Mercury lied to me during tech training)
    Rattling noise will be gone, but unless the can is drilled(a bad idea), motor noise varies very little.

  5. Member
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    Jul 2013
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    #25
    I have no intentions of changing the tuner, it ran great with the stock tuner so I will keep it that way.

    Two guy's mentioned that you could remove the drive shaft housing to fix the tuner, but some saying to remove the power head.

    In either case,, will the drive shaft housing and/or the exhaust housing need to be remover to fix this???

  6. Member
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    LONGVIEW TEXAS
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    #26
    MOE if you pull pwr head (which I would ) pull gearcase and plates under head ds housing can stay on swivel brkt
    .................................................. ...the scariest thing in life is the unknown ...................................

  7. Member
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    #27
    Quote Originally Posted by JOE54 View Post
    MOE if you pull pwr head (which I would ) pull gearcase and plates under head ds housing can stay on swivel brkt
    Thanks Joe!!

  8. Member
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    LONGVIEW TEXAS
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    #28
    sho MOE
    .................................................. ...the scariest thing in life is the unknown ...................................

  9. Member
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    Galena, Kansas
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    #29
    I will let ya all know how it goes!!

  10. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Apr 2008
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    Greenville, SC (US)
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    #30
    BTW... the gasket pictured above if from earlier 2.5L models. It doesn't "seal" anything, but sure doesn't hurt to have the added vibration dampening.

    Between using the gasket, BOLTS, and Red Liquid Loctite on the tuner, I've had very good luck keeping them in place.

    Most of you know if I cut my arm I bleed "black"... but the person who came up with NYLOCK nuts to retain the tuner already had a couple screws loose.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  11. Member
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    Jul 2013
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    Galena, Kansas
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    #31
    Thanks for all the info guys!

    I got the Job done, it turns out it used bolts not Nylock nutz. So this must have been updated by either mercury or after it was rebuilt under warranty by the previous owner.

    The screws were all loose, but nut none had completely falling out. They now have red lock tight on them!!

    I was hoping the tuner was my 150rpm loss 1.5mph, but made no difference. Going to recheck compression, camera scope cylinders and new spark plugs (about 2 years old, and look great and all 6 look identical). Probably carb rebuild, been about 3 years. And see if I can get the rpm back. Maybe just a tune up is needed.

    Not an issue of need to go fast, I guess Im just inTUNE like the many here and notice the little things that may indicate and underlying issue. Normally I should turn 5600 easy, especially during this cool down we have had in missouri. (I have a digital tach, similar to a tiny tach to supplement my regular tach). Everything else seems to be good, boat hull, prop, engine height, etc. etc that could effect RPM's.

    I do not think it has anything to do with it, but.....The only thing I changed I do not normally do, I put a full tank of 91 non ethanol in it, may try putting back in my normal 87 ethanol, I always use the fuel additives recommended. The tuner was very clean as far as carbon build up BTW!!!

    Instead of starting a new thread I will keep this one going on my findings, unless you guys think I should start a different thread.

    Thanks again Guys for all your help you provide, it is nice to see people with such passion in there line of work!!!
    Last edited by moetorola; 10-21-2019 at 02:25 PM.

  12. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #32
    Continue here is fine. Check your Sync-n-Link Settings, confirm actually reaching WOT position on each carb, and don't forget the simple items (such as a skewed jackplate, worn striker plates, minor prop scuffing- all of which can add up).

    Good thinking to go back to the fuel you normally run (preferably when you have the level down to a safe/low level).


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor

  13. Member
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    Jul 2013
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    Galena, Kansas
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    #33
    Rechecked Compression.
    My old compression gauge was a freebie from a friend, the type you had to hold in the plug hole by hand, I always questioned it's accuracy.
    So I picked up a new compression guage that screws in, from orielies.

    The results, about 122 in all cylinders.

    I thought maybe the gauge was broken and getting stuck at 122, no way could that be possible to be that close. Checked it with my compressor, and it was fine. Rechecked engine same result 122 except cyl1 had 124 this time.

    FYI, this was a cold test, it was dark and cold outside, will get warm numbers some other time. But it gives me a better feeling on those numbers.

    Also camera scoped cylinders, looked good and the pattern looked good on piston tops in comparison to other pictures I found on line.

    Link and sync looked good, carbs butterflies are balanced and snapped shut.

    Spark plugs looked great, all identical color brownish gray. Regaped them while I was in there too .40 I think the book specs it for.

    Will be placing an order with European marine for carb gaskets, needles and seats, probably go ahead and get plugs also.

    One other thing I thought off, it seems to smoke more than I recall. Could be related to 91octain or maybe needle valve leaking. Bleed lines and check valves have been recently checked. I probably need to check the idle air valve on the cyl head for proper operation.

    So will be taking boat out this weekend hopefully, so will be getting some of that 91 out, and going back to my normal 87. And give an update on that result. One step at a time, I suppose.
    Last edited by moetorola; 10-28-2019 at 12:25 PM.

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