Dissapointed in 9.9 4 stroke

[stopngo]

I was going to close an eye on the excessive weight but
A......To fast for trolling at minimum throttle.
B......Caused my entire 12 ft aluminum boat to vibrate including the rods simulating constant strikes
HELP pleaae
2025 EFI 9.9 MERC Low usage

 

[Mc Tool]

I was going to close an eye on the excessive weight but
A......To fast for trolling at minimum throttle.
B......Caused my entire 12 ft aluminum boat to vibrate including the rods simulating constant strikes
HELP pleaae
2025 EFI 9.9 MERC Low usage

They have 360⁰ crank phasing (both pistons go up and down together )and no ballance shaft so it will dance about at low speeds.
You may be able to alleviate both issues a bit by fitting a shorter prop so its doing more revs at the same speed which will smooth out the shaking and / or slow down your trolling speed .
Ally dinghies dont have a lot of mass and will shake about more than a fibreglass one under similar circumstances.
If you have just moved from a 2 cylinder 2 stroke with 180⁰ piston phasing ( they all are )...one piston going up while tother goes down .....cancelling each other out , and twice as many firing strokes......the new motor will seem quite shaky .

 

[boscoe99]

I have seen vibration reducing pads that go between the motor's clamp bracket and the transom.

Switching to a propeller with less pitch can help to slow down the minimum idle trolling speed. As can tilting the motor up somewhat to vector the thrust to a less efficient position.

Piston engines and aluminium boats are just known to have certain vibration tendencies. Us old dawgs never gave it a thought. Thought it was supposed to be that way. Just the nature of the beast.

 

[Mc Tool]

Mercury does make mention of "dynamic dampening" rubber mounts instead of a ballance shaft ....probly to save weight . Changing the composition of the mounts probly more effective than adding more, but youd hope Mercury would have optimised them during development .
Its one of them things where if they design it to be smooth running at medium to full revs its gunna vibrate at idle to low speed , and vice versa.
Maybe you could put down your beer can and pie and just hold on to your fishing rod

 

[racerone]

Take it to a Mercury dealer to be checked out / set-up.----Do you run fuel out of the carburetor when not using it for a few days >

 

[Mc Tool]

Take it to a Mercury dealer to be checked out / set-up.----Do you run fuel out of the carburetor when not using it for a few days >

Does "EFI" not mean electronic fuel injection ?

 

[racerone]

NOT thinking straight today.----Good catch.

 

[boscoe99]

Although they have been out a while, a 9.9 EFI model does not readily compute.

How low in HP will they go?

The amount of gasoline injected at idle must be in the nanograms.

 

[Mc Tool]

NOT thinking straight today.----Good catch.

Not trying to catch you , just wanting to make sure it didnt mean something else . Some of these outboards has a lot of letters in their model designation .

 

[Mc Tool]

Although they have been out a while, a 9.9 EFI model does not readily compute.

How low in HP will they go?

The amount of gasoline injected at idle must be in the nanograms.

Yeah , you'd thing a basic carb would be cheaper and just as green , I guess you need to be seen to be green , there are probly dudes that would pass up on a carbed motor if there was an efi one next to it .