1971 merc loss of power

[adam89k]

Motor is in tip top shape, but when under power it takes a long time to get the boat on plane and up to speed. Carbs have been done, compression is good, fuel is 50:1, tank vent is full open.

Once boat is on plane it goes like crazy, just no bottom end.

Plugs seem to get a coating off oil on them in a short period of time. Boat is a wild cat, motor and boat are a package deal since day one no mods what so ever. Motor is a 75hp.


Any ideas ????????????????????????????

Previous thks to responders.

 

[Barnacle_Bill]

Re: 1971 merc loss of power

Could use a little more info. Like what size motor, boat, size of prop and tach reading at WOT.

 

[adam89k]

Re: 1971 merc loss of power

The motor is a 75hp prop is stock no tach. Cylinders have also been scoped,
no damage what so ever.

 

[adam89k]

Re: 1971 merc loss of power

Sorry the boat is a wild cat, motor and boat are package deal from day on no mods what so ever.

 

[j_martin]

Re: 1971 merc loss of power

Any sneezing or popping?

 

[adam89k]

Re: 1971 merc loss of power

Any sneezing or popping?

No none, it almost seems like a fuel problem but I have a new line on it

and everything else seems ok.

 

[j_martin]

Re: 1971 merc loss of power

No none, it almost seems like a fuel problem but I have a new line on it

and everything else seems ok.

Try opening up the idle jets 1/8 turn. If you set it so it idles perfectly, it won't launch. You have to set it a little rich, maybe even advance the idle timing a bit to compensate.

hope it helps
John