1988 225 Evinrude Looper shakes at low speeds

speedbt89

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Jul 11, 2012
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I have a 1988 225 evinrude that has been driving me nuts since i bought it. The engine runs perfectly at WOT with no hesitation or break ups. The motor seems like it is shaking too much and sounds very loopy :confused: while i am putting around the 5mph areas. it seems that at different throttle positions it sounds like a different motor. So far i have changed the flywheel, timer base, stator, rebuilt all the carbs, replaced all of the recirculation check valves and hoses, new plugs ql77jc4 gapped at .040, new wires. The jets on the carbs are 47 on the top one and 34 on the bottom one. The fuel is fresh i have changed the filters many times and they look fine. timing has been set to 6 ATDC. im running out of ideas and any suggestions would be greatly appreciated. Thanks in advance
 

speedbt89

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Re: 1988 225 Evinrude Looper shakes at low speeds

I double checked the compression again just to make sure, first i let the engine warm up for 10 mins. Then i shut it down removed all 6 plugs, put the shifter to WOT, and cranked each cylinder over untill the needle stopped moving. the results were 85 85 85 port and 90 90 87 starboard from top to bottom.
 

boobie

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Re: 1988 225 Evinrude Looper shakes at low speeds

The compression sounds real good for that mtr. Could you post a video of it running ??
 

speedbt89

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Re: 1988 225 Evinrude Looper shakes at low speeds

I just went out for a test drive and the motor was running perfectly, went for a quick blast and when i got back down to idle speeds it started acting up again. its kinda hard to tell when its at the dock... i notice it more when im actually driving and moving the throttle up and down. i am able to get it to purr at like 500 rps if i shift it into gear and not gas it at all. i have the quick start temp wire grounded out because when it is activated the motor wants to rip off the transom. ive also tried different tilt levels but it didn't change anything.

 

boobie

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Re: 1988 225 Evinrude Looper shakes at low speeds

I think you're chasing a ghost. Back in the days when those mtrs came out we used to call them " lopeing loopers ". I'm sure somebody else will chime in and disagree.
 

Haffiman

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Dec 17, 2009
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2,454
Re: 1988 225 Evinrude Looper shakes at low speeds

Don't see anything shaking out of normal???
However if the boat/hull/transom is not rigid or a rubber mount is failing, vibrations might be transferred.
 

speedbt89

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Re: 1988 225 Evinrude Looper shakes at low speeds

its not so much the shaking im worried about, it almost feels as if a cylinder is kicking in and out when it happens.
 

Haffiman

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Dec 17, 2009
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Re: 1988 225 Evinrude Looper shakes at low speeds

Check engine temp(both banks with an IR gun) and thermostats as well as be sure carbs are in synch.
 

speedbt89

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Re: 1988 225 Evinrude Looper shakes at low speeds

ok ill check the temps tomorrow. i replaced both thermostats and the rubber diaphram gaskets this year already and i quadruple checked the butterflys and the linkages.
 

boobie

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Re: 1988 225 Evinrude Looper shakes at low speeds

How's it run at mid range and WOT ??
 

speedbt89

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Re: 1988 225 Evinrude Looper shakes at low speeds

what rpms do you consider mid range. WOT is perfect.
 

speedbt89

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Re: 1988 225 Evinrude Looper shakes at low speeds

it seems like anything over 1600 rpms is fine it almost feels like a mix of power cutting out and the engine loading up and dropping a cylinder for a sec. the rpms bounce a little bit when the shaking occurs
 
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