1988 Force 125: Carb rebuild and timing set needed?

[ahickman]

Re: 1988 Force 125: Carb rebuild and timing set needed?

Just got the tachometer in from ebay purchase. Wound it around spark plug wire #1 a couple of times and set it to 2 according instructions above. Ground the white wire on the chassis. Adjusted idle screw until I got about 1100 RPMs in neutral with the prop in a large tub of water. I started adjusting the air/fuel mixture, but got intimidated because I was not quite sure what I was listening for. Lots of blue smoke and got annoyed. Questions are:

1. Do I adjust one carb at a time, turning 1/16 a turn at a time and listen for a rise in idle each time?
2. When it get to a rough idle, I back it off and then go for the other carb?
3. Should the smoke clear as I get closer to the right mixture????

 

[Jiggz]

Re: 1988 Force 125: Carb rebuild and timing set needed?

According to the link and synch sticky posts and also on the Clymer's Manual this is how you adjust the air screw.
First do the initial setting of 1 1/4 turn out from lightly seated for each carb (from hereon I will mention carb but it actually applies to both carbs but you do the setting one carb at a time)
Start the engine make sure you have cooling water. Let the engine come to operating temp (you can easily tell this when water starts to spray or mist out of the middle leg nostrils, which is an indicate the thermostat has already opened)

Now start turning the air screw CCW slowly while listening for the engine rpm. The engine (usually) will start to increase in rpm and then will start getting rough idle (due to too rich of air-fuel mixture), at this point stop turning the air screw CCW and mark its position and number of turns from initial setting. Now turn the same air screw CW while again listening for the engine rpm. It will again rise in RPM and then will become rough idling (due to too lean of air fuel mixture). Stop turning the screw CW, mark the position and number of turns from previous position. The middle point of this two extremes is the appropriate setting for the air screw.

Now you need to do the same for the other carb. These settings for the air screws are not final yet. As you run you engine you can still tune it up according to your needs. If you like a quick shot out of hole, you usually want to increase the fuel air mixture by turning both air screw CCW. However, sometimes this results in high fuel consumption and also thick exhaust smoke and sometimes carbon build up in the cylinder and also on the plugs. To reduce exhaust smoke, you can turn the air screw CW but beware, you should never go below 7/8 turn from lightly seated (highly recommend lowest setting is 1 turn from lightly seated). For this can result in too lean of air fuel mixture which can damage the cylinders and pistons.

My air screw settings are just a little less than a turn out from light seated. The purpose is for fuel economy and prevent thick exhaust smoke. If you like running your Force at WOT most of the time, I recommend you set your air screw no less than 1 1/8 turn from lightly seated.

There is no such thing as smoke clearing, otherwise you will not see smoke. With 2 cycle engine there will always be smoke except the difference is if its heavy or light.