Force 120 Idle Jets

[geohei]

Hello, I have a late model (1998) Force 120. I found in the manual it says to start at 1 turn. I see I should start at 1-1/4 per the sticky. I found other info that says start at 1-1/2. What I found is a get a stable idle at nearly 2 turns out. At 1 -1/2 to 1-3/4 the idle bobs up and down. I'm trying to get it stable and hold just below 1000 rpm in neutral so when I put in gear it doesn't stall (like while docking and going forward to reverse). I have it performing acceptable with that setting (2 turns). Otherwise it runs great. Hole shot is awesome. Any thoughts here? Thanks, GK

PS. I have other posts but started a new one since this is a new topic...

 

[jerryjerry05]

Re: Force 120 Idle Jets

Couple of thoughts.Idle in gear should be 750-800rpm.More than that can cause damage.and hard shifting.Check the static timing.What's the compression?Spark good?J

 

[geohei]

Re: Force 120 Idle Jets

Good hot spark (new stator & trigger), good compression (about 150 on all 4). I need to check static timing as soon as I get timing light. It idles in gear about 800 at this setting (idle jets 2 full turns out). I can try to get it a little slower. The problem has been cough stalling when shifting from fwd to rev while docking.
My question is am I looking at carb rebuild? I'm running Merc Quickleen is my fuel now but only about 6 gallons so far. Maybe after 20 I'll see a difference...if that stuff is any good...Thanks, GK

 

[Frank Acampora]

Re: Force 120 Idle Jets

You always need to give the engine what it wants, but two turns out on the idle needles does seem a bit much. It would make me curious. Most of these engines usually like to be at 1-1/4 out.

If you have the time, remove the carbs, remove the float bowls, and check the float level. With the carb inverted, the float should be level with the carb casting with just its own weight. If it is above level, this will translate to a low float setting at running and will also mean slightly lean running. The cough and stall may be related to the two turn setting.


While you have the carbs off, might as well clean them. Partially clogged idle circuits could result in a two turn setting while high speed would be affected only slightly. Use WD 40 or something similar. Do not use carb cleaner as it may harm some of the sealers that are applied at the factory.

After cleaning and setting the float level, then try re-setting the idle needles. Do not go too lean--see FAQ at the top of the page.