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 .

 

[Ifishmuskie2]

Ya efi on a small engine isn’t worth it for fuel savings. Maybe worth it for easy starting. But I have a 20hp and a 5 hp and they both start easy enough for me.
It may be possible to turn the low idle down.

 

[stopngo]

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

Don't feel bad.Right after I took posession of it I spent a half hour looking for the choke...still have not found one.

 

[stopngo]

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.

My 9.9 2 stroke was smooth all the way

 

[stopngo]

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 .

Thank you and you hit the nail on the head.I would still have my 2 stroke if It hadn't put a rod through the block.

 

[Mc Tool]

Thank you and you hit the nail on the head.I would still have my 2 stroke if It hadn't put a rod through the block.

What sort of 2 stroke was it , and do you still have the carcass ?

 

[stopngo]

1989 Merc 9.9 2 stroke yes still have the carcass.Bought a 1992 9.9 mariner which ran great at idle but currently apart due to vertical play in the rod bearings.Hoping to get that back in order and I will be selling the 4 stroke.Too heavy for a 78 year old.

 

[dingbat]

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 .

Where do I sign up..

I have mowers with a Kohler 301(12hp) and a Kohler ECV749 (27hp).

Each motor uses roughly the same amount of fuel to mow the yard. It’s just that one mows the yard in half the time of the other… and I don’t have to run fuel out of the carburetor when not using it for a few days”…lol

 

[Mc Tool]

1989 Merc 9.9 2 stroke yes still have the carcass.Bought a 1992 9.9 mariner which ran great at idle but currently apart due to vertical play in the rod bearings.Hoping to get that back in order and I will be selling the 4 stroke.Too heavy for a 78 year old.

I was just thinking that I am happy with the cylinder block , crankshaft assy and pistons I bought for my Tohatsu off ebay ,(from some place called Oversea ) ...got it all for about 600nz . I dunno if your into pulling things to bits but thats a budget (pretty much whole )powerhead . And I did see 9.9 merc/ tohatsu stuff there too.
As for the weight ....I know what you mean ...I have recently dropped my brand new 6hp Zuki 4 stroke ( broke the handle which is part of the whole lower cowling ) trying to get it off the boat and on to it stand ....and that weighs only 20kg

 

[Scott Danforth]

Im not a fan of EFI on small motors. however that is me.

 

[boscoe99]

My 9.9 2 stroke was smooth all the way

The two stroke was firing twice as often at a given RPM.