How do I eliminate 2 cylinder shutoff on 125Hp Merc?

[GlastronSF]

I have a 1999 Mercury 125hp ELPTO. This motor has the feature that shuts off two cylinders at below approx. 2000rpm. I am looking to know if someone can direct me on how to eliminate this feature.

From what I have learned two of the carbs have different idle jets, but much more than that I am having trouble finding. It is oil injected, so I assume this ties into the equation.

Help is much appreciated.
Mark

 

[achris]

Re: How do I eliminate 2 cylinder shutoff on 125Hp Merc?

The best advice to you is don't try and reinvent the wheel. Mercury built those engines to idle on 2 cylinders because they idle like crap on 4.

If you don't like the 2 cylinder to 4 cylinder transition, then change to a prop to one that gets the engine into the LOWER end of the max rpm at WOT.

Are you having problems or are you asking because 'someone' said it was a good idea?

Chris.........

 

[GlastronSF]

Re: How do I eliminate 2 cylinder shutoff on 125Hp Merc?

I will touch wood while I say this... The motor runs very well. It is strong and I like the compact size that it has. I was looking to elimate the 2 cylinder feature figuring it would simplify the engine even more and make the mid range a little more enjoyable for cruising. We mainly ski so it is not the end of the world. I have just seen bits and pieces written here and there about people that have done it... just looking for someone to give the aftermath results.

 

[achris]

Re: How do I eliminate 2 cylinder shutoff on 125Hp Merc?

Years ago I had a customer who wanted to do the same thing. I told him it was a silly idea, but he insisted. So I bought in two new carbs and fitted them. It idled like a pig. He was happy, for about a week. Bought the boat back to me to have the old carbs put back on. Then bitched because I didn't refund him on the new carbs....

If you want the transition to be less noticeable (when you're just cruising), then put a bigger prop on. This will now mean that you need 2 (at least) props. If you try and ski with the bigger prop you'll find the acceleration too slow (some people call it 'hole shot').

Chris.........

 

[flyinbryan]

Re: How do I eliminate 2 cylinder shutoff on 125Hp Merc?

I will touch wood while I say this... The motor runs very well. It is strong and I like the compact size that it has..

definitly what achris said.

i know someone with the same configured 125hp, and i must say its probably the smoothest idling 100hp+ motor ive ever seen (although i dont know if im the best judge of a smooth idle, being a 50hp triple owner) (funny side note on that subject, i used to tell my 10 year old son our 50 idled like that because it had a race cam in it, lol, hes 24 now)