Carb jets metering air?

[Brew2]

'86 Evinrude 140 looper....been having fuel/carb issues for a while...think I finally am coming close to getting it sorted out, but want to confirm something regarding the low/medium jets on my carbs.<br /><br />I think they are metering air (as opposed to fuel) and therefore a smaller numbered jet would actually create a richer fuel mixture...correct?<br /><br />Thanks.

 

[kgw]

Re: Carb jets metering air?

Brew2,<br />Yes that is correct,I have the same motor. The idle and intermediate are for air and the main jet is fuel

 

[Dhadley]

Re: Carb jets metering air?

And never run that motor under a load with the airbox cover off. That will lean it out a bunch.

 

[Egil]

Re: Carb jets metering air?

Hi..!<br />I an new at this forum... Name is Jan-Egil and I live in the north of Sweden by a lake named Storuman.<br /><br />I have the same engine.. It is two jets in front of the carburators. On the two upper carburates the jets are marked 16 (upper) and 24. On the two carburaters below the jets are marked 20 (upper) and 24.<br />Why is it different jets on the carburators? And what jets can I use... (Storuman lies on 350 meters above the sea level) It runs rich on idle and just abowe... runs fine at 3500 rpm to 5500 rpm.<br /><br />Engine data:<br />Evvinrude 140<br />BE140TLCUA<br />G1445500<br /><br />Hope the spelling was not too bad.. <br /><br />//Jan-Egil

 

[Egil]

Re: Carb jets metering air?

Forgot to say that 350 meters is 1148 feet.<br />Guess You don´t use meters... <br /><br />//Jan-Egil

 

[Brew2]

Re: Carb jets metering air?

Hi and welcome Jan-Egil.<br /><br />I know that the manual indicates that the port and starboard carbs have different low/medium jet settings (the two jets you are referring to), however, I don't believe the upper and lower carbs should have different jets settings (I'm at "on the road" for a few days so I can't confirm this in the manual at the moment, just going by memory). In other words, I believe that both upper and lower carbs on each side should have the same jetting (remember that I'm just guessing based on memory).<br /><br />As for the appropriate jets, all the numbers you referenced seem familiar (16,20,24) so I think your problem may just be a matter of rearranging the jets between your carbs. As for the altitude issue, sorry can't help you there. Maybe start a new post with that question.<br /><br />If you haven't got a manual, I'd go get one. It will advise on the appropriate jet placement as well as solve any number of other problems you may encounter.<br /><br />If you're still encountering problems, I'd start a new topic on the forum as your questions might not get the attention they deserve at the bottom of my post.<br /><br />Good luck and keep us updated.<br /><br />Cheers.

 

[Egil]

Re: Carb jets metering air?

Thank You for answer.... Yes .. You´r memory is correct. I had contact today with a company that sales parts and asked them what jets is original. He said that it is 16 / 28 on the SB side and 20 / 28 on the BB side of the engine.<br />So .. someone has mounted the jets incorrect and used 24 instead of 28 for the low/idle jets. <br />I hawe just bought this boat and when I tested it on sea-level it was running rather well. When I started it in Storuman it was running too rich on idle and low speed. Tomorrow I will mount the jets correct and see how it works.... probably I have to change the 24-jets I have to the 28 that is original. <br />Good idea too start a new topic on the altitude.... !<br /><br />Thanks again..!<br /><br />//Jan-Egil