Johnson spl carb adjustment

[thedude]

So I just rebuilt the carbs and put in new plugs in my 1993 48 hp spl. It was not running at idle but would start choked right away. I eventually got it to idle but it isn't perfect. I believe I still need to adjust the low speed needle in the carb to fine tune the carbs. A few questions and things I would like to confirm.

1. Should I remove the needles completely and clean them? And spray carb cleaner into the open hole?
2. I understand the default position is to completely seat the needle and then back off 1.5 turns. Then adjust slowly from there.
3. What is the best way to tune 2 carbs? Top then bottom? Adjust them one at a time or make the same adjustment for both?
4. I understand I should do fine tuning in full submerged water (not just muffs). Some recommended in lowest forward gear?
5. I had a fair amount of oil coming out the exhaust after burning nearly a gallon of gas. Is this normal unburned oil from idling so long or could it be related? Or could I have another issue like spark? I put brand new plugs in but didn't check the gap.
6. Should I adjust the idle adjsutment screw after all this and do I need a tach to get the rpms precise?

Thanks for all the help! A video of it idling.

https://youtu.be/113gGu1UGO0

 

[DaleH]

Cleaning - I only - and rarely EVER have to clean carbs off the motor and then only clean from small orifice to larger ones, else you force the dirt/crud deeper inside.

Whilst carbs are on the motors I prefer to run a pre-mix cocktail of Seafoam through it and let it soak/sit, 15-mins @ higher idle followed by a 15-minute soak.

Idle - Adjustment & speed are TWO different settings! Tune in water, for backpressure, and adjust one carb until it runs the smoothest/highest without leaning out, then adjust other carb. Recheck 1st one.

Test - Go out for a run to high speed and when you throttle back to idle speed, make sure she doesn’t conk out, most likely too lean, or else repeat the entire procedure.

Oil - Normal ...

 

[CedarRiverScooter]

Info above is right on, just want to add that engine should be warmed up good while adjusting carb idle.

PS - Make sure thermostat is working too! I've had them stuck open.

 

[DaleH]

Added info .... just reviewed my OMC service manual for the 60hp

-Verify that the throttle arm is fully against the idle stop

-With above held in place, should be 0.010" clearance between throttle cam and the cam follower

-See picture for CARB MIX (e.g., needle valve) adjustment, then test at high speed

-Idle speed is typically a mechanical adjustment to the linkages, picture shows location for their 60hp as an EXAMPLE ONLY

 

[thedude]

Thanks Dale. I was able to find the process in the manual in the Tinboats manual repository! I will report back when I get a moment to lake test it. My guess is that is was too rich which was leaving some unburned fuel in the carb body and running rough at idle (or not at all in some cases). I still could not find any info on whether i should remove the needle all the way and clean or just adjust it. They do sell the needles separately so I'll plan to 1)adjust 2)remove and clean or 3)buy a new needle.

 

[DaleH]

I still could not find any info on whether i should remove the needle all the way and clean or just adjust it. They do sell the needles separately so I'll plan to 1)adjust 2)remove and clean or 3)buy a new needle.

... have never replaced one in 50+ years of boating, if that helps you ... and I'm only 50-something years old!

 

[thedude]

I also plan to check and clean the screen in the fuel pump. Ordered a spare screen and o ring.

 

[Stumpalump]

My 48 spl ran good enough but stalled some. I pull the adjustment needles out and use aresol sea foam. After putting the needles back it ran the same. I started at 1.5 turns out but that was not even close. I think I wound up closer to 2 3/4 out.