'98 115 Johnson - Idle Mixture Needle Adjustment ?

[Grizz1288]

I have had an engine 'sneeze' or cough during very low idle (fully warmed up) and have been trying to trouble shoot.

So, I went against everything I have read on the internet and bought a PDF version of the SELOC shop manual for this motor generation. Looking for two things in said manual. 'Link and Sync' procedure and anything about idle tuning.

My idle RPM is dead on at 650 when in the water and in gear and the engine is properly going in and out of 'warming mode'.

The initial needle valves were at 10-1/2 turns out from seated.

I have attached the portion of the manual that goes over the procedure for tuning the idle needle valves. My questions are:

1) 1st of all as I said this is from SELOC, if anyone has the actual Johnson/Evinrude shop manual and can share its procedure for this I would love to compare them.

2) Does 1/8th of a turn really make enough of an adjustment? I was tuning it yesterday (in the water, fully warm, and in gear), and I could really tell that I was in the right ball park, bc it would either idle just fine or clunk out in a second. I was using full/half turns to fine tune (before I read this) and was getting decent results.

3) This manual procedure makes it seem that each carb is done separately and the valves do not need to be set at the same exact amount of turns. I have read that they should all be set the same (from wisest of internet posters that is). So, what is the verdict, if I turn top left in 1/2-turn do I turn the rest and go from there or can/should each carb be adjusted separately, under the conditions depicted here for the best running engine. What would be the harm in them being set differently?

3.5) Is there a way to tell which cylinder is causing the sneeze?

4) Of all the things that this says must be in order to set the tuning i.e. (in gear, in the water, level trim, fully warm) nothing addresses the fact that the air box and cowling are removed to do these adjustments, uhhh that seems very important in regards to the air flow into the motor. Although I will say, when I got the motor idling fine without any sneeze, putting back on the cowling and air box had no effect.

So, I've gone on and on and anyone reading this post at this point is a true kind soul. Thank you in advance for any insight and help regarding this matter. If you have any further questions that may lead to a more comprehensive response let me know please.

P.S. I didn't mention it above but the carbs were just fully rebuilt and cleaned

 

[racerone]

Model # is ??-----Any other trouble shooting done on this motor ?

 

[Chris1956]

My OEM service manual says 5-3/4 turn open for '98 115HP 60* V4.

Did you clean the idle passages in the throttle bodies, or just the carbs? Did you clean the air bleed orifices?

floats are level with inverted carb cover + - 1/32"?

 

[Grizz1288]

Model Number is J115SLECM. The last issue was power pack related and that was replaced.

I actually did not clean the idle passages and now that seems silly. I guess that is the obvious course of action now. They were definately all 10-1/2" turns out when i started messing with them. I'm at 8 turns out now and with some cleaning maybe ill get down to the 5-3/4 turn range. I am guessing that 1/4 changes are the way to tune it up after the cleaning.

Anyone know about the #3, are all of the carbs supposed to be synced up perfectly for the fine tuned engine. I am guessing in a perfect world, yes, but not sure if it can cause damage if they aren't once fully tuned.

When you screw the needle out, that allows more fuel to flow is that correct?

Thanks.

 

[Grizz1288]

Also, I assume that the air bleed orifice you are referring to is the 'intermediate orifice" seen and referenced in these two pictures.

 

[Chris1956]

Yes those are the bleed orifices. I have found that they do get dirty. A blast of gumout will clean them up.

Carbs are independently adjusted, for best running. High speed jets are fixed, so the engine will be getting the same fuel amount (or mostly) at high speed, eliminating lean running.

CCW movement of the idle mixture screws makes them richer.

You may remove the side covers on the throttle bodies to get to the idle needles and idle passages.

 

[racerone]

Have you checked float bowls.-----They can be warped.

 

[Grizz1288]

Thanks for the info Chris. I'll get those areas cleaned up and go from there. I have access to the idle needles and bleed orifices without removing any side covers but will most likely pull the carbs to fully inspect them again, its become a routine procedure at this point.

I actually replaced all of the float bowls when I rebuilt the carbs, they were all cracked. I guess there was a reason they made these carbs out of plastic but it is unknown to me.

 

[racerone]

How does the motor run at full throttle now ??-------Plastic float bowl are cheaper to manufacture.------Plastic parts can be molded / ready to install for less money than aluminum parts.-----Cost cutting at a high level.-------So set the needles at 6 turns out.----If motor sneezes there is something wrong and trouble shooting is required.

 

[oldboat1]

If no sneeze at 6 turns out, adjust each carb 1/8 turn leaner (clockwise) until you get a lean sneeze. Back that needle out 1/8 to 1/4. If sneeze corrected, troubleshoot that cylinder.

 

[cdembek]

So set the needles at 6 turns out.----If motor sneezes there is something wrong and trouble shooting is required.

I am in the same boat... what would be the other troubleshooting?