Timing a 2000 Mercury 115

Mswanson9095

Recruit
Joined
May 18, 2019
Messages
3
Hello,

First post on here! I recently bought a new to me 2000 mercury 115 inline 4 cylinder carbureted 2 stroke. Wasn’t running to well at WOT so I rebuilt the carbs, synched them, rebuilt fuel pump, and swapped out the plugs. Bought a timing light from harbor freight with the dial on the back. Set the idle timing at 2 degrees BTDC (set the timing like at 2 and made sure it was at 0 on the power head). Then when I went to adjust the max timing at 25 degrees BTDC (set the light to 25 and made sure it was 0 on the power head) the top timing screw had to be turned practically all the way in. Motor seems to run great at all rpms now I just wanted everyone’s input on this as it seems odd the top timing screw is now almost turned all the way in to get 25 degrees max timing. Has anyone else experienced this?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,047
Facts---------You only set maximum timing advance !!-------Timing never or rarely needs to be checked / changed on these motors.------Idle timing is the pojnt where throttle OPENS UP.------Actual idle timing does NOT MATTER and is retarded to adjust idle speed.-----This motor only idles on the top 2 carburetors.----The bottom 2 carburetors start to work at around 1800 RPM.------What are the compression numbers ?
 

Mswanson9095

Recruit
Joined
May 18, 2019
Messages
3
In the manual it says to adjust timing at 2 degrees for idle and then adjust max timing at 25 degrees. Don’t know compression numbers but leak down was performed and was at 9%. Have you ever adjusted the max timing? Was the max timing adjustment screw practically bottomed out too achieve 25 degrees?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,047
I have a motor just like that for parts.-------You should never have to make wild adjustment to timing on a modern outboard motor.------Unless of course someone was guessing and did the " I wonder what will happen if I adjust this " approach to repair work.----A factory manual is almost a must have on that model.-----Note the actual timing at smooth idle does NOT MATTER.------That 2 degrees number is the point where throttle plates open on acceleration.
 
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