Low speed jets on a 115hp

[stalker170]

I have a 1992 115 inline 4 cylinder Mariner.<br />I have owned the boat for two years. Ever since I have owned the boat it ran a little bad on low end. I checked the setting on my low speed jets. The book said they should be set at 1 1/2 turns out. Mine was set out 1 3/4 on both carbs.<br /><br />I put the muffs on last night and when I turned the jets in to 3/4 to 1 turn out from bottom, the boat run perfect at that setting. <br /><br />My question is, Is it ok to run at this setting?<br />I know I have leaned the motor out on low end. But that is were it seems to run perfect. I do not want to cause any damage to my motor. <br /><br />This motor is on a bass boat, I do not run it at a idel for long. I run to my fishing spot and use my trolling motor.<br /><br />Is this like most float carbs. I am only pulling through this jet at a idle? And when I start to trottle up, I start pulling through the main Jet?<br /><br /> Stalker

 

[Barnacle_Bill]

Re: Low speed jets on a 115hp

1 and 1/2 turns is the starting point for adjusting carbs so you can get the engine started after rebuilding the carbs.

 

[Chris1956]

Re: Low speed jets on a 115hp

Stalker, It is normal for the engine to idle well at a lean setting. I think that when you try to accelerate under load, the motor will bog or stall. If so you will need to richen up the carbs until it will accelerate smoothly.<br /><br />The proper idle mixture is one that will idle reasonably well, and accelerate smoothly!

 

[emckelvy]

Re: Low speed jets on a 115hp

Adjust for best idle and acceleration, but you must have it in the water, warmed up and in fwd gear when you make the mixture adjustments. Adjusting on the trailer won't help much, as once you're in the water, it'll be too lean. <br /><br />Remember this one goes lean at idle on some of the cyls then kicks in with an accelerator pump at around 1800 rpm, so they idle very strangely out of the water (usually will idle quite fast), and act much differently in the water.

 

[stalker170]

Re: Low speed jets on a 115hp

Thanks guys,<br /><br /> I did plan to make the final adjustment in the water. It has been a little boggy when you accelerate ever since I have owned the boat. Meaning I need to turn them out. Just the opposite than what I am now. So maybe I have another problem. I guess I will not know that until I get her in the water and hit the throttle.<br /><br />Lets say she is really boggy now that I have turned them in, meaning I will need to go back to the 1 1/2 turns. Any other ideas on what I should look at next to fix my idling problem.<br /><br />Stalker

 

[stalker170]

Re: Low speed jets on a 115hp

Put the boat in the water this past weekend and the motor runs perfect. She idels smooth and when I am coming up to speed she is smoother. I guess she was a little rich on low end. So if your Merc or Mairner is running a little bad at a idle, you might want to turn your low speed jets in just a little to smooth it out. I went in 1/4 to 1/2 of a turn. Mine only has the low speed jet adjustment on the top two carbs.<br /><br /> Stalker