mercury 850

[mmeeks]

i have an older mercury 850 thunderbolt and i need help. how do you adjust the idel with the 2 carbs?

 

[JaseBosto]

Re: mercury 850

you take it to a shop because I could NEVER get it perfect.
Before I had my sterndrive, I was an outboard man with that exact engine at one time. The way I got it "close enough" was to crank the screws all the way in, then go a half turn out on each screw, while attempting to start. When it started I would continue adjusting outward a quarter turn at a time on each carb till the vaccuum was at a peak.

 

[mmeeks]

Re: mercury 850

i can adjust it by advancing the distributor but when i do it the motor wants to bog under a load. im assuming your talking about the air mixture screws cause thats about the only thing i see you can adjust. but now i have the motor running good under a load but when i put it in nutreal its idealed up to high and i dont wont to strip anything out in the lower unit by putting it in gear.

 

[JaseBosto]

Re: mercury 850

sounds like you need to keep playing with the air mixture screws to me. you want your rpms somewhere around 6-800 when engaging forward or reverse. Once you get the idle right try to plane off and see if she runs right....I hate outboards...

 

[Chris1956]

Re: mercury 850

Set both carb idle mixture screws to 1-1/2 turns out from lightly seated. Make sure the link and sync is right on. Now start and warm up the motor. Idle in gear and try to accelerate. If it stumbles, open the top carb 1/8 turn and try again. If she still stumbles, openb the bottom carb 1/8 turn and retest. Continue until you have smooth acceleration and reasonable idle. Two carbs is not too hard. Try to synch three carbs or more. My Johnny has six carbs....