Merc 850 Idle Adjustment

N

Nial

Seaman
Joined
Dec 14, 2004
Messages
66
Hi there<br /><br />My 1976 Blueband Merc 850 is currently idling around 1500 rpm and then at 1000 rpm when in gear. I've read that this might be a bit to fast and might be damaging my gearbox. I adjusted the idle screw on the side of the motor and set it back to 1000 rpm when not in gear. I still idles about 1000 rpm when in gear with this new adjustment but when I take off and try pull a skier is has a serious loss of power. I adjusted the idle back to the original 1500 rpm and I have all the power back and it runs great. Can anyone shed any light on this problem? Thanks<br />Nial
 
L

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: Merc 850 Idle Adjustment

Nial, the engine could be a tad lean, makeing it weak on acc. it should idle about 750 to 800 in gear
 
timmathis

timmathis

Lieutenant
Joined
Apr 24, 2005
Messages
1,295
Re: Merc 850 Idle Adjustment

Try adjusting the air screws at the carbs. Then check the timing or vise versa.. Tim
 
M

MercFan

Petty Officer 1st Class
Joined
Dec 31, 2005
Messages
347
Re: Merc 850 Idle Adjustment

Nial,<br /><br />Failing what Laddies said you might be too far advanced on idling.<br /><br />Clams' great post on Link and Sync does not mention timing at idling since this is set by ear. But a good starting point is 0 deg BTDC (or dead on TDC) at idling and 3-4 deg BTDC at 1st throttle pickup. When you have the timing at TDC at idling use the mixture screw to get a proper 800-1000 rpm idle. Then try it in gear and hole shot.
 
M

MercFan

Petty Officer 1st Class
Joined
Dec 31, 2005
Messages
347
Re: Merc 850 Idle Adjustment

Also, before playing with the timing, try the screw the other way (Screwing it out, hopefully) Make your mixture richer. Your idling will go down doesn't matter which way you screw it. Either leaning it out (Screw in), or drowning it in "richness" (My word, Screw out).<br /><br />You just need a lotta fuel at idling, to get a proper pull-away / hole shot.
 
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