125 Idle Adjustment

E

erosenwinkel

Petty Officer 2nd Class
Joined
Apr 22, 2011
Messages
130
Had my 125 hp 1258x5a out last night. I checked the rpm's because I thought it was idling kind of high. Approximately 1100 at idle and 650 at idle in forward gear. Goes into gear without stalling, etc. Are these numbers what they are supposed to be ? I performed the link and sync on the sticky. At WOT I got 4850 rpm, 37mph on my Bayliner Capri 18 1/2 footer. Good water flow. Started easy cold and hot. I just thought maybe the 1100 was a bit too high and the 650 was a bit too low. Any way to correct them independantly? I am satisfied the way it runs, just wanted some input.
Thanks, Eric
 
Frank Acampora

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: 125 Idle Adjustment

You can not adjust them independently. Idle speed in forward gear is to a degree dependent upon the prop pitch--higher the pitch, lower the RPM. Neutral speed is a function of the in-gear idle speed and no specification is given. That is why the setting is done in gear, on the water, in forward gear.

650 is a little low, usual is 700-750, but if the engine does not stall and will idle reliable for longer periods (like when in a no wake zone) then why fight with success? After all, the only reason for setting idle speed is so the engine doesn't stall.

Also, the question arises: How accurate is your tach at these low RPM?
 
P

pnwboat

Rear Admiral
Joined
Oct 8, 2007
Messages
4,251
Re: 125 Idle Adjustment

There really isn't any way to adjust the RPM's independently ( in neutral, and in gear). If it's running well and not stalling, I would leave it alone. I've caused myself a lot of grief from trying to "tweek" my motor to get it just right. After several hours of tweeking, I felt lucky just to get it back to the way it was LOL!
 
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