Johnson Seahorse Knobs

[Gubbo]

I have got an old Johnson Seahorse 2hp outboard. It works erratically, alternating between flat out whizzing to spluttering stop all on the same throttle setting.
can anyone help me identify the functions of the two adjusting knobs on the control panel (upper and lower) Both have an "increment" guide (similar to a volume control) but I don't know what I am meant to do with them. I presume one is the mixture control and perhaps the other a slow idle??.
Please can someone let me know. It would be great if you can advise on the correct sequence for setting them up as well.

Thanks a lot
Rich

For details of my boat see www.sailpast.co.uk

 

[andy_wilson]

Correct.

The mixture control adjusts the slow running jet to give smooth running at trolling speeds.

Fill with fresh petrol/oil mixture and give the motor a good blast under load to blow out the crap.

Engage gear and set throttle just above idle and experiment with the mixture control until running is smooth.

Remove the knob and centralise.

Use whenever it runs a bit lumpy at your chosen throttle setting, it will usually need adjustment between the marks.

Char fishers etc. will set the throttle stop at a suitable fast idle, adjust the mixture setting to suit, and troll up the lake fishing without having to give it any further atention.

 

[c4pt]

From my early 2 stroke motorcycle days (BSA bantams for those that are interested) The 2 knobs will be mixture and tickover. Try setting them as follows.
1, Make sure the throttle is not open by adjusting the linkage or cable so that the slide or butterfly valve in the carb is fully Closed.
2. Screw the mixture screw in till it hits bottom GENTLY it only needs to touch.
3. Then back it out one and a half turns. This should allow the motor to run with the throttle partly open.
4 Adjust the tickover screw to a fast tickover. (so that its not running on any bypass jet, if fitted)
5.Then tweek the mixture screw in and out till you obtain the fastest running without touching the throttle..
6, Once done adjust the tickover screw to a nice steady tickover.
The engine should run quite happily. A good test is if you can run it straight upto max throttle without the engine baulking. Its best to replace the plug, points and ht cap to get the best results. There was also a device knocking around then that was like a see through spark plug so you could actually look at the mixture burning under running conditions. I'M not sure if they still exist
good luck. (ps make sure the fuel tank is vented so a vacuum does'nt build up and cause fuel starvation)