Idles Fine, But Runs Rough On Idle Up

[~Airman~]

Hey All, I got a 1989 85hp Force Outboard. It would not get past 7mph on the water, but the few times it did it would run Great wide open...if you backed off it you went back to 7mph. I rebuilt the carbs, replaced the floats, needle valves and fuel pump. Starts right up now, but when idle up it changes tones and has alot of exhaust smoke (not oil). Any ideas? thanks guys!


BTW I use a 50:1 ratio

 

[steveclv]

Re: Idles Fine, But Runs Rough On Idle Up

Have you checked the timing? Also have you checked the small screen in the dip tube that goes into the tank? Mine was totally clogged with varnish so worth cleaning and checking yours.

How did you set the mixture on the carbs? Close them both so they are lightly seated and the open them out 1 turn. Then open one out until the engine coughs and note how many turns and turn it back in until it coughs again - set it at the mid point between the two. Repeat for the other carbs.
On the water, try accelerating and if the engine backfires, richen the mixture, it it dies then lean the mixture but never go less than 1 turn open. Richer mixture is better than lean on a 2 stroke.

 

[foodfisher]

Re: Idles Fine, But Runs Rough On Idle Up

My lot of smoke issue was cleared up by cleaning the fuel recirculation system.

 

[steveclv]

Re: Idles Fine, But Runs Rough On Idle Up

My lot of smoke issue was cleared up by cleaning the fuel recirculation system.

Details, details, we need more details

 

[foodfisher]

Re: Idles Fine, But Runs Rough On Idle Up

Pull hoses, clean them and fittings w/carb cleaner. Just squirt it in till the gunk quits coming out. Replace hoses w/new if needed.

 

[~Airman~]

Re: Idles Fine, But Runs Rough On Idle Up

yes, I was thinking the carbs needed adjusting too. But I can't seem to find the idle screws :/ I'll be looking for those, thanks

 

[steveclv]

Re: Idles Fine, But Runs Rough On Idle Up

The idle mixture screws can be accessed through the hole in the black covers that cover the carb inlet if it's anything like my older 125 as the screws are on the top of the carbs at the 1 o'clock position when facing the inlet. Start with them gently seated and back them out 1 full turn as your starting point.

Remember, slightly rich is better than slightly lean.