Carb mixture adjustment

[Scallywag1]

I have a 1989 85hp with a rebuilt powerhead. I'm still running the 1 pint to 5 gal. mixture. I had to adjust the carbs due to bogging. It would run fine at forward idle, but when getting out of the no wake zone it would die. I adjusted the carbs as my clymar manual advised. Set the idle close (no tach). Set all 3 adjustment screws at 3/4/ turn out. Started motor, ok at idle.Turned counterclockwise until rough idle, turned clockwise never achieved rough idle. The mixture screw seated before rough idle. All 3 carbs the same. I set all to 3/4 turn out seems to run good. I have some smoke when running.
Any ideas as to why motor seems to run ok with such a lean mixture? Will the carbs need readjusted when I start to run the 50:1 mixture? Thanks

 

[pnwboat]

Re: Carb mixture adjustment

Typically, when the engine stalls when going from idle speed to higher speed, it usually an indication that it's running too lean. Try richening the mixture a quarter of a turn at a time until it stops stalling. Adjust the idle speed with the idle adjustment screw on the vertical tower shaft.

 

[roscoe]

Re: Carb mixture adjustment

If your post is correct, you ARE running 50:1 already.

You should be running 1 quart of oil per 6 gallons for break-in.

 

[john from md]

Re: Carb mixture adjustment

I hear what you are saying about your engine running fine at 3/4 turn but that is not a correct setting for an 85hp with today's fuels. I know the book says 3/4 but most are set at 11/8 with the lower sometimes being set at 1 due to it loading up.

Running the idle mixture too lean will result in a lean mixture at WOT because the idle circuit works through the entire power range with the type of carb that these engines use.

Did you have the carbs rebuilt when the power head was rebuilt? If so, they may have adjusted the floats too high and this MAY cause your condition. I say MAY because it is just a guess.

I would make sure that your overtemp switch works just in case.

John

 

[malayan]

Re: Carb mixture adjustment

Thanks ..
I have an 85 HP force and I noticed a drip or two of fuel from one carb.
Maybe the float is set too high and it is coming out overflow?

Also:
how do you check the HIGH temp switch is working?

Thank you

 

[john from md]

Re: Carb mixture adjustment

Checking the overtemp switch is easy. All you have to do is ground the orange wire on the overheat detector with the switch on. The switch is located on the head next to the number two spark plug.

I suggest that you just jumper the wire to the spark plug shell with a piece of wire or screwdriver as removing the nut to take off the wire can sometimes break the switch.

Regards,

John

 

[sailingwest]

Re: Carb mixture adjustment

I would advise that you are very close to doing damage from lean burn a 3/4 turn out from seated 1 and a 1/4 turns out from seated is a far better and much safer point to start off, It might be a good idea to check your fuel pump diaphram for pin holes as my engine was doing the same as yours and fuel pump diaphram resolved problem. Jim B