Idle Jets go where?

[glengold]

1977 55hp evinrude 2 cyl. The idle jets are different sizes for top/bottom carb. Which one goes where? Smaller one on top?

 

[HighTrim]

Re: Idle Jets go where?

upper carb

http://www.marineengine.com/newparts/part_details.php?pnum=OMC0318823&ptype=&Engine=&Model=

lower carb

http://www.marineengine.com/newparts/part_details.php?pnum=OMC0317473&ptype=&Engine=&Model=

 

[glengold]

Thanks hightrim. So smaller on bottom.

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[glengold]

Re: Idle Jets go where?

OK guys, I'm at my wits end with this motor. I took the carbs apart and the jets were installed incorrectly, smaller jet on top (30). I switched them so 31 on top, 30 on bottom. Now the motor idles poorly. It stalled out trying to get on plane several times. It also wouldn't start easily after being warmed up. I would have to put it in fast idle to get it started. When the idle jets were switched (incorrectly) the motor would start with a click of the key (if warmed up of course), in neutral. It would never die on me when I tried to get on plane.

The problem with running it like that is I'm concerned that it is running lean on the top cylinder. It will start to make a loud rattling sound after running on plane for a few minutes. WOT was slighly less with the jets installed correctly too. Should I change the jet sizes or order new ones? They looked really clean when I changed them out, so I didn't soak them in cleaner. A few sites mention re-jetting these motors but I havn't seen what they re-jet to.

 

[glengold]

Re: Idle Jets go where?

I am considering 31's in both carbs. Any reason not to try a richer idle mix?

 

[5150abf]

Re: Idle Jets go where?

Have you cleaned all 3 sets of jets recently?

The idle jets don't do much above idle and have very little to do with wot, I would look at the main and mid jets and actually clean them with a wire, soaking doesn't clean them, and blow out all carb passages and confirm the correct jet is in the correct spot.

 

[glengold]

Re: Idle Jets go where?

I believe I only have 2 jets in each carb, but could be mistaken. Main jet in the bottom, Idle jet up top, then the needle and seat.

I'm going to go through them again tomorrow and report back. Does anyone know what size the main jets are supposed to be? I've not taken these out, but have poked a piece of wire through there.

 

[5150abf]

Re: Idle Jets go where?

The mid should be on the top back of the carb, yours could be different but that is where it is on mine and I have an '81 50.

Pull each jet and run a stranded copper wire through it, just pull back strands till it just fits and run the wire through all the passages as best you can and blow them out, the air in a can works really well if you don't have a compressor and using Sea foam helps also.

As a tip, do one carb at a time and keep the cover with the jet so you don't get them mixxed up.