New Merc 4HP 6 MPH

[Cjlovi]

Have a new 4HP Merc 2 Stroke.

The throttle stops responding at 1/2 turn. Maximum attainable speed is 6MPH. Current set up is 12' Porta Boat. Minkota 55LB Thrust Motor. Group 27 Battery.

Now I've seen these motors push the PB over 10MPH with two adults weighing total 400lbs plus gear.

Any idea as to why the throttle stops responding at 1/2?

Thanks

 

[merctech]

Max throttle adjustment is probobly out. Any dealer should be able to set it back for you.

 

[timebandit]

bogging stalling? mess with choke to see what happens. Or maybe just a throttle cable.

 

[Cjlovi]

No bogging or stalling just max's out at 1/2 throttle. The butterfly on the carb keeps going but no response after 1/2. Going back to the dealer tomorrow.

 

[fastjeff]

Too much prop pitch for the application?

Jeff

 

[timebandit]

Don't assume the the engine was brand new. Might have been a "no hassle" return. The carb gums up from sitting.

 

[Cjlovi]

It's at the dealer now. I found this web site http://www.internetoutboards.com/product_list.asp?id=65 and upgrading the carb will be my next step.

Thanks

Carl

 

[timebandit]

A word to the wise about "big box" stores in the US.

 

[Cjlovi]

Do you have any suggestions on purchasing a 6HP Carb for the 4HP Merc? Most places are outa stock.

Thanks

Carl

 

[timebandit]

How are you going to fit a WMC carb on a 4HP motor?
Why can't the old one be cleaned out and rebuild?

 

[Cjlovi]

It's brand new! It just doesn't have enough umph! It's my understanding the 2011/2012 Merc (Tohatsu) 4-5-6 HP motors are identical except for the carbs which are interchangeable. Installing a carb with larger jets increases the HP to 6HP.

 

[timebandit]

I am confused. You said 2 stroke before, and that means that the 6HP is a twin cylinder. That carb does not fit a 4. It can't fit.
Now you say 4 stroke. There is more to it than just jetting. Exhaust tuning and spark advance, too.

 

[Cjlovi]

Ah! 4 Stroke my mistake. Age is affecting my memory

 

[fastjeff]

I know the concept! Could be there's simply too much load for the hp. Also, 4 strokes tend to be gutless at low speed.

Jeff

 

[timebandit]

You may need a smaller prop.

 

[Cjlovi]

The load is me, motor and some fishing gear. Boat weighs 68lbs. I'm searching for props but that is challenging due to thrust/rpm/pitch ect formulas. LOL

 

[guyjg]

A word to the wise about "big box" stores in the US.

And that word is....?