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Bad vibes !

F

Fish Head

New member
Hello all ! Newbie here, Ive been lurking around for a while and decided to sign up and learn from you all !
I have a 2005 25hp Mercury Bigfoot that vibrates very bad at Idle, shakes the boat like crazy, in and out of gear. Throttle up and it smooths out and runs fine....Its driving me crazy ! Any Suggestions would be greatly appreciated !
 
It's possible one of the magnets on the underside of the flywheel has come loose
and shifted....causing things to be way out-of-balance. Take a look see.
 
guyjg said:
Is it firing on both cylinders at idle? Prop isn't bent?
Click to expand...

It is firing good..... runs good and strong, just vibrates like all get out when its at idle, even out of the water.. I cant see anything that would look like the prop is bent ?? Thanks for the info !
 
have you pumped the bulb to see if that helps?have you put a timing light on it to see fire?it should be smooth out of gear at idle...then when you idle in gear it would not be a merc if it didnt vibrate some til about 1500 rpm...
 
Here we Go ! When the motor is running at idle both in and out of gear, I squeeze the bulb and nothing happens as far as the vibration. It gets hard the first few squeezes then goes soft( that doesnt sound to good) like it is just pumping gas. What should be happining ?
As far as the magnets under the flywheel, I am by no means a mechanic so I will leave that to the pros along with with checking if both cylinders are firing.
I did take the plugs out and clean them up , they didnt look bad at all ? So I guess the next thing to do is drop about $500 at the shop ?
 
You MAY be able to see the magnets just inside the lower edge of the flywheel.
You are looking for a curved plate....several inches long.....maybe 0.25" thick.
Turn the engine over slowly (with the recoil starter) until you see it.
Mark the outside of the flywheel at the middle of the magnet (with a pencil).
Turn the engine over slowly and find the second magnet.
Mark the flywheel at the center of the second magnet.
If the two marks are not 180 degrees apart, one of the magnets has shifted.

If you take the engine to a shop, you might want to have them agree to
call you if the cost is going to be over $200.
 
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