94 125 merc

[dutchdog]

I have a 94 125 merc. with the 2+2 idle. I understand that the carbs. control the 2 cyl. idle with the mixing screws on the top 2 carbs. The mixing screws on the bottom 2 are blocked off. I have been told that if you put needles in the bottom 2 carbs and bypass the acc. pump that it will idle on all 4 cylinders. I was wondering if anyone has tried this? I run this engine on a 17' Nitro. It runs 59 to 62 mph depending on load. Any thing else to hop up motor would be helpful. Already have Boyesen reeds, 26 pitch stainless prop, jack plate.

 

[achris]

Re: 94 125 merc

I have a 94 125 merc. with the 2+2 idle. I understand that the carbs. control the 2 cyl. idle with the mixing screws on the top 2 carbs. The mixing screws on the bottom 2 are blocked off. I have been told that if you put needles in the bottom 2 carbs and bypass the acc. pump that it will idle on all 4 cylinders. I was wondering if anyone has tried this? I run this engine on a 17' Nitro. It runs 59 to 62 mph depending on load. Any thing else to hop up motor would be helpful. Already have Boyesen reeds, 26 pitch stainless prop, jack plate.

Not a good idea! They idle beautifully on 2 cylinders. If you start messing with them they idle like crap. Is there a reason why you would need to do it?

 

[dutchdog]

Re: 94 125 merc

Mine does not idle very well. I have been through everything according to the manual. I don't like the way it is from about 1000 rpm up until it kicks in. The dealer said the one way valves needed cleaned so I replaced them. I have sync. the linkages, done everything I have been told to try.

 

[Faztbullet]

Re: 94 125 merc

Needles wont do anything as carb passages is not drilled........ actually the Boysen reeds will hurt your idle on this motor as you cannot richen up the idle enough on the bottom 2 carbs per the Boysen instructions

 

[pigeon laker]

Re: 94 125 merc

I have a 2000 115,basically the same motor.For the past couple of years I have tried numeruos things to get it running better.This past weekend I tried some experimenting with the idle mixture on the top 2 carbs.I have both screws open between 2 to 3 turns not the recomended 1 1/2 turns and it has never idled better.I never got to take it for a good run due to weather.Before fattening the idle the motor would shake and sometimes stall if the idle speed was lower than 800 rpms.Now at 600 rpms it almost runs like a car motor.Hopefully when I take it for a run everything else will have improved the way idling did.

 

[Dave1027]

Re: 94 125 merc

The 2+2 design was done to make it idle smoother. A inline 4 cylinder 2 stroke cannot idle well by nature. The designers thought the drag of two non-firing cylinders would have a smoothing effect. The jury is still out on whether it actually does. Mine's not the smoothest either.

 

[dutchdog]

Re: 94 125 merc

If I try to richen the mixture on the top 2 cyl. the engine loads up and dies. As for the Boysen reeds, you do not want to richen the mixture unless the engine backfires. This is what Boysen tech support told me.