1971 6 hp Evinrude won't Rev High Under Load

[mmmckillip]

I just recently purchaced a 1971 6hp Evinrude (6102G). I've rebuilt the carb, replaced the spark plugs, the reeds, and water impleller. It runs great in neutral but runs slow and sounds bogged down when under a load. I checked to see if it was running on all cylinders by removing one spark plug wire and running it and them removing the other spark plug wire and running it, which it seemed to run fine on both. Also I checked the fuel pump to make sure it wasn't leaking and it wasn't. Compression looks good (75 PSI). I need some suggestions on where to go next. PLEASE HELP!

 

[F_R]

Re: 1971 6 hp Evinrude won't Rev High Under Load

Do you just have too much load for it to push?

Was the high speed jet clean when you were in the carburetor?

We really can't diagnose it from here, only guess.

 

[jay_merrill]

Re: 1971 6 hp Evinrude won't Rev High Under Load

How about the high speed orifice? Did you remove it, clean it and make sure that there is no junk in the passageway that leads into the bottom of the bowl? Same question for the high speed nozzle - is it clear? Did you install the new high speed nozzle gasket? Is the float tab adjusted properly, so that the float needle valve opens at the correct position, allowing sufficient supply of fuel to the carburetor? Lots of little things to pay attention to, when rebuilding a carb.

BTW, do not try to remove the HS nozzle, unless you absolutely have to. There is a screwdriver slot in the bottom of it, but the nozzle is brass and they tend to break on older motors. Just make sure that the passageway is clear.



???

 

[mmmckillip]

Re: 1971 6 hp Evinrude won't Rev High Under Load

Do you just have too much load for it to push?

Was the high speed jet clean when you were in the carburetor?

We really can't diagnose it from here, only guess.

Everything in the carb looked good and clean once I got done with it. I dont think its under to much load its just a 12' alluminum john boat and every once in a while the moter will get up and go like it is supposed to

 

[kenmyfam]

Re: 1971 6 hp Evinrude won't Rev High Under Load

Compression (done already)
Spark (with a spark tester when it is acting up)
Fuel delivery
Spark plug condition (when it is acting up)

 

[btaylor507]

Re: 1971 6 hp Evinrude won't Rev High Under Load

Sounds like the motor has a big load on it or maybe isn't planing the boat right. When it does plane enough it revs up to its normal rpms. Most people I know with 12' Alum have at least a 15hp on the back.

my 2 cents

-Bill

 

[mmmckillip]

Re: 1971 6 hp Evinrude won't Rev High Under Load

I had the motor mounted toward the right side instead of in the center to make it easier to steer. Would that affect the load?

 

[mmmckillip]

Re: 1971 6 hp Evinrude won't Rev High Under Load

Sounds like the motor has a big load on it or maybe isn't planing the boat right. When it does plane enough it revs up to its normal rpms. Most people I know with 12' Alum have at least a 15hp on the back.

my 2 cents

-Bill

I had the motor mounted towards the right side of the boat insead of in the center to make it easier to steer. Would that affect the load?

 

[jay_merrill]

Re: 1971 6 hp Evinrude won't Rev High Under Load

It might affect top end slightly, just because the offset thrust requires a bit of "countersteer," which creates a bit of drag. Other than that, what you have done isn't a big deal.



???

 

[mmmckillip]

Re: 1971 6 hp Evinrude won't Rev High Under Load

I think I have decided that the motor is just to small for the boat.