1990 Force 120 carb question

[KenOverton]

Re: 1990 Force 120 carb question

Thanks for the assistance everyone. Got everything back together and I am now able to adjust fuel mixture on both carbs. Had the boat out 2 times now and it runs great. Had to set idle a little on the high side to prevent dying when shifting into gear, but that is not an issue to me. Idle is set at 1000 - 1100. Will a standard auto test tachometer work on an outboard ( the kind that connects to the spark plug wire)? I have one of those and my timing light has the tach feature built in but both read way higher than my boat tach.

I know now that the motor is under-propped. I have to make sure my tach is working correctly and then get all the numbers to try and figure what prop I need. At full throttle it buries the tach past 6000 and there is major prop-slip. I don't even have to trim to get the boat on plane. Like I mentioned, I will have to get all the numbers and post that in the prop section for some assistance.

Thanks for the help.
Ken

 

[itzmepete]

Re: 1990 Force 120 carb question

Recommended rpm is between 5000 and 5500 is max rpm. Idle is with boat in gear . My 1999 120 force idles at 1000 to 1100 but its at 900 to 950 in gear. A regular car tach won't work or I should say has to be set up right. I think if you have it set for a 4 cylinder it will read twice as high as a two stroke fires double than a four stroke. Try setting it up as an eight cylinder.

I need to take my float bowls off as I suspect some dirt in there. Engine starts/runs great at any speed, WOT is 5250 which is max for my 99 but when I tilt it up it slows and stutters. Tilting it up brings the bowls level and I suspect some dirt in the bowls may be sliding down onto the jet tube area. I had a Volvo Penta that when throttled up and the nose of the boat went up it did the same thing. Ended up being dirt in the bowls. Just took a quick look at my carbs bowls and did notice a line connected to the bottom or at east I thought I did. What did your bowl set up look like and what did it entail to pull the bowls off?

 

[treat44]

Re: 1990 Force 120 carb question

Agree x3 here , clean the bowl , make sure the vent is clear , carb cleaner through everything else and let 'em run ! I just did new idle tubes on mine , What a pain but I took the cheap way out , hobby shop for tubing stock and made mine . I will never pull them out again !!

Can you elaborate on what size OD, length tube, etc. you used for your idle tube fix. New to carbs, I was referencing my Merc manual which states to press out idle tubes. I ruined one and need a fix. Part not available through dealers?