1976 70hp Evinrude wants to be choked

[Tao of Funk]

1976 Evinrude 70hp

I have rebuilt the carbs (correctly I believe), replaced the fuel lines, tested the fuel pump, and checked for proper spark.

When I try run the motor up to full throttle (in the water and in gear) it bogs around 2000rpm. I had a friend in the boat today and I had him advance the throttle (in gear) while I blocked the carbs with my hand. When I restrict the air flow to the carburetor the cylinder fires and the motor accelerates. It seems as though the increase in suction allows the fuel to pass more readily through the jet. I adjusted the float to allow more fuel into the float bowl and it didn't help. I adjusted the float to lower the fuel level in the bowl and it didn't help. Once the engine achieves full throttle/cruise speed, whatever you want to call it, it'll run all day long up there. It'll idle all day long too.

I double checked the carburetors to ensure they were cleaned properly and they are clean. There is no restriction in the jets, main or low speed. These are fixed orifice jets by the way. So why do the jets require the aid of choke to allow fuel to flow through them?

Thanks for your help!

GB

 

[Tao of Funk]

Re: 1976 70hp Evinrude wants to be choked

I also put Boyesen reeds in this motor...

GB

 

[Tao of Funk]

Re: 1976 70hp Evinrude wants to be choked

Well I did find junk in one of the main jets and the nozzle gasket missing on another. Crazy, I have rebuilt carbs a hundred times and never been so careless as to miss the nozzle gasket. Oh well, sometimes you have to go back to square one.

GB

 

[jtexas]

Re: 1976 70hp Evinrude wants to be choked

So glad we could help!

 

[Tao of Funk]

Re: 1976 70hp Evinrude wants to be choked

So what do you think of Boyesen reeds, I mean are they worth what the company says they're worth? I put the reeds in this motor before I put it on the boat so I can't tell if they made a difference or not. I put the same reeds in a '69 55hp rude and they helped it idle better...

GB

 

[tashasdaddy]

Re: 1976 70hp Evinrude wants to be choked

never used them.

 

[jtexas]

Re: 1976 70hp Evinrude wants to be choked

me either. did you install 'em in the last motor hoping for improvement, or were the old ones faulty?

 

[Tao of Funk]

Re: 1976 70hp Evinrude wants to be choked

Hoping for improvement, and got it. That motor didn't idle for cr*p. I had tried all kinds of setting tweaks and such but it still was a major pain around the dock. After I put the Boyesen's in it idled much better (in gear that is). I got the two stage reeds (I think they're the only ones available for those blocks).

Anyway, I'm a sucker for aftermarket parts so I threw them on my 70hp when I got it.

GB