'99 125 HP 2 Stroke Merc Runs Rough at low RPM

[Y Knot]

Hi-
Have had this problem for a couple years. Runs really rough until I increase throttle to 2500 or 3000 RPM, then runs like a top. Thought it was dirty carbs, so I rebuilt them.
Leaning toward thinking it is ignition problem now. As far as I can tell, the ignition system was made by CDI. It does not have a switchbox on the side of the engine. There are a bundle of wires coming out of the bottom of the stator, and they go straight to the individual coils (one for each cylinder), and a pair go to what I think is a voltage regulator or rectifier. Would be more than happy to bring it to a mechanic, but they are all backlogged for months, so they say. So I am destined to find the cure on my own, I guess.
Can anyone advise a troubleshooting procedure?
I have not replaced spark plugs and plug wires, assuming if any were bad it would run rough at all RPM ranges, not just low speed. Maybe this is wrong assumption.
Any/all input appreciated

 

[flyingscott]

Do you have a factory manual? When you rebuilt the carbs did you do the fuel system? Accelerator pumps fuel pump?

 

[Y Knot]

Do you have a factory manual? When you rebuilt the carbs did you do the fuel system? Accelerator pumps fuel pump?

I do not have a factory manual. Rebuilding the carbs , making sure the fuel line/squeeze bulb is in good shape, and adding an in-line good quality fuel filter were the only things I did to the fuel system.

 

[flyingscott]

You must have a factory manual for a 2+2 motor.

 

[QBhoy]

Is this maybe just typical behaviour of a 2+2 ? If you aren’t used to them…they can be very different from most any other engine, I’d think

 

[flyingscott]

Absolutely not. They are smooth good running motors that need a manual to properly link and sync and diagnose.