1986 140 evinrude question

[dcolpitts]

I have a 140 on a 1974 mako center console, I have owned this boat for five years with the same performance problem. It idle, boysen reed. but when I power up It takes a long time to get thru mid range, and then runs great on the high speed jets. carbs have been clean and rebuilt 3 times since I,ve owned it, the latest time too weeks ago. It,s annoying because it will fall off a plane at about 2600 rpm, thus making rough ride in any 2 foot seas. Anybody have any ideas. Thanks

 

[ob]

Re: 1986 140 evinrude question

What WOT rpm is the engine capable of as propped?

 

[dcolpitts]

Re: 1986 140 evinrude question

last weekend 5800 rpm. Have heard of this lagging midrange before?

 

[dcolpitts]

Re: 1986 140 evinrude question

On the lack of midrange, could this be a timing base problem? Is it possible for the base to loose sensitivity to the magnets or the magnets have lost some. I know I,m streching but I can't find the lack of midrange problem.

 

[Dhadley]

Re: 1986 140 evinrude question

The early V4 loopers had some pretty big cards. Are you running the stock airbox including the inner air baffle?

 

[dcolpitts]

Re: 1986 140 evinrude question

yes, stock air box with inner baffle and had recently added boysen reeds hoping to help. No change. The mid range jets are stock 16, 18,'s. Is it possible that the midrange jets are just worn out thus allowing to much air in?

 

[Dhadley]

Re: 1986 140 evinrude question

The jets dont wear. What grade fuel are you running? Is it 100% fresh? What spark plugs?

 

[dcolpitts]

Re: 1986 140 evinrude question

dhadley, the fuel is regular 86 octane, last time out 2hours old. I'm running 100% syntetic penzoil with vro. New power head with 50 hours 130psi across the board. plugs are champion QL77JC4 gapped @ .040

 

[dcolpitts]

Re: 1986 140 evinrude question

I mispoke on the size of the midrange air jets earlier. the starboard side have #16, the port have #20's