johnson 2hp outboard tuning - what tuning screw does what?

[PaulR]

in preparation for summer cruise lugged our very old (c late 70's) 2 hp johnson to the boat - started 2nd pull and chugged round ok but bit temperemental at lower revs - manual for it long gone so not sure what the 2 screw adjustments do - both have same symbol next to them and I wonder if one is slow setting and one fast setting-if so presume fiddle with one at low revs till engine runs ok and the other at full revs to do the same - anyone know if that is right please??

thanks

 

[paddywackcocker]

I think you will find that one is for the idle setting and one for the air/fuel mixture. If it has developed a poor idle you would be better off popping the fuel bowl off and removeing the mixture screw and give it a good blow out with compresed air. Refit the screw, screw home (not to tight) and then back off 1.5-1.75 turns. new fuel and a plug and she should be back to normal. If not give the idle screw a tweek.
The idle adjustment screw will eather screw onto the throtle lever on carb body or will go into carb body and raise throtle slide. The idle screw will (if my memery serves me right) angles down at aprox 45` into the carb body. It should be easy to work out before you start wich is wich. if that has not helped try and adjust eather at meedium revs, one will do nothing (idle screw) the other one will when screwed in increece revs momenteraly and then dye away and if screwed out will make the 2 stroke run over fueled (called, four stokeing) with smoke

 

[Talbot]

The only other screw on the side of the carb may be just a dampening screw tfor the throttle, to stop it going to idle when in use.

 

[VicS]

Go to the Bombardier- Evinrude website
click "parts and accessories", then "engine diagrams", then go to "Johnson" in the drop down list, then pick the year, then the hp, then the model number, then "carburettor", "zoom in" a couple of times and you will be able to identify the adjustment screws.

If I've looked at the right one the slow running adjustment is the top one and the main jet is the bottom one.

It would be wise to be sure the carb is clean before you start adjusting it though.

 

[jkim1]

Vic s is correct, I have fitted a control knob to the lower one (the high speed adjustment).

 

[PaulR]

thanks all - will have a go and see how I get on,

Paul