here's a really dumb question

[Mr.Stuart]

I'm almost embaressed to ask this, I should know the answer.

take a look at the picture, what does that knob do? it's located next to the choke knob on my 89' Evinrude 9.9 electric start.

the outboard runs really well, idles down so low that in gear it won't even move the boat, but last time I had the outboard out on the river, I messed with that knob trying to figure out what it did, I turned it from one stop to the other, it traveled it's entire distance, and I couldn't tell where it did anything, I heard and saw no changes in the outboard either at low idle or full throttle, when I got the motor, that knob was set at dead center, where it's at now, and that's where I left it after messing with it.

so, can anyone tell me what it is, and what it does?

sorry for the cheesy picture, it's a cheap camera and doesn't do close up all that well.

 

[Texasmark]

Re: here's a really dumb question

SWAG. OB's used to have variable high and low speed jets. So you had 2 knobs protruding from the front of the engine. Seems designers figured that you can fix the high speed jets with no problems so they eliminated one of the confusing points.

That leaves the low speed jet. I'll throw my hat into the ring for that. To support that theory, the marking indicates a small area cw and large area ccw which would correspond to the fuel/air ratio change as you turn the knob.

Seems OB's with few cylinders are very tempramental under varying conditions at the lower speeds and idle.

Since you moved it and got no response, either it is out of range (screwed in or out too far), the needle is damaged (from being screwed in too tight), hence can't function properly, or you were not operating the engine in the range where it is designed to be effective when turning it.

Might (while recording your turns/partial turns) carefully turn it in (cw) till it stops. How many turns was that? Somewhere around 1 1/4 to 1 3/4 should be optimum operating positions (for most engines I have operated). If the turns are correct, you need to investigate the tip to insure that it is conical and not scored. Be careful, as if it is what I think it is, there will be a spring around the shaft that you don't want to loose. If scored get a new one.

My best guess and no question is a dumb question.

Mark

 

[MarkV_Deep6]

Re: here's a really dumb question

My old 9.5 kicker has the same adjustment and it is indeed for low idle control. It will not produce a noticable change unless you lean it out so much that it causes sneezing at idle, or fouls plugs when too rich. You probably just richened it up some and seemed to make no change.

I set mine by turning it back to lean and the richening it to just remove the sneeze. This will give the best performance. Leaving it to rich will cause carbon build up, foul plugs, and just waste fuel.

 

[tashasdaddy]

Re: here's a really dumb question

this is what it is for, yours, may be disconnected, ( the linkage not there).

http://forums.iboats.com/showthread.php?t=167352

 

[Mr.Stuart]

Re: here's a really dumb question

the knob on mine only travels 360 degrees, right now it's set in the middle between the two stops, whereas it will only go 180 degrees in each direction, I should have loooked under the cover to see if anything is attached to it, TD could be right, and it may be disconected.

 

[tashasdaddy]

Re: here's a really dumb question

that's correct it only travels 180 in each direction, for fine tuning, has to be disconnected to make major adjustments. there is a linkage inside the cover.

 

[Mr.Stuart]

Re: here's a really dumb question

that's correct it only travels 180 in each direction, for fine tuning, has to be disconnected to make major adjustments. there is a linkage inside the cover.

I took the cover off and took a look, it goes into the plastic housing that covers the front of the carb.

so this is for low idle adjustment?

 

[flabum]

Re: here's a really dumb question

t's definately the idle mixture adjustment knob. To go byond the 360*, just pull the knob off and rotate it past the stop and re-install it.

Since you say it is running fine, there is no need to mess with it.

 

[Mr.Stuart]

Re: here's a really dumb question

t's definately the idle mixture adjustment knob. To go byond the 360*, just pull the knob off and rotate it past the stop and re-install it.

Since you say it is running fine, there is no need to mess with it.

I'm going to leave it alone, no need to fix something that's not broke, I just wanted to know what it was, I'll pay closer attention to it next time i have it out on the water and see if I can notice any difference when I turn it