Main jet sizes in a 200 Merc

[RaceCarRobbie]

Does anyone know how I can find out what size main jets I should be running in my 2.4 200 merc? Thanks in advance.

-Rob

[Ranger976]

help...year motor , serial #, on top of each carb there should be a # WH20, WH28, WH31,.........

[T-REX]

Gotta have them numbers!!!

[RaceCarRobbie]

First off, thanks for the responses. The Scream and Fly Community is great. I should probably first fill you guys in on my problems and explain why I am asking about main jet sizes. I cooked the top piston on my 1992 Merc 200 power head # D167874, model #1200422MD (I think a 2.5 liter?). I had a mechanic look at it he told me the engine was running too lean. I mix the gas and oil myself and am quite precise. There were no clogs anywhere, carbs were clean and he suggested I run bigger jets (the ones in there were 0.066s on all 3 carbs).

I was able to get a used but clean 1989 200 powerhead from a friend powerhead # C199968, model # 1200422GD (I think a 2.4 liter?). I swaped some of my stuff over (my carbs and powerpack) but am using my friends voltage regulator and intake. My mechanic put larger jets in the carbs so it runs richer so that hopefully I don't cook another piston. I believe the jet sizes and 0.082 on the top carb and 0.08 in the middle and bottom carbs.

The engine runs nice and smooth and all cylinders are firing but my boat is now very slow. It is slow to plane off and the top speed is only 37mph at 4600rpms. I have a 24' Superboat and previously I was doing 54mph at 5900rpms. I do see a little wet oil inside my carbs. Am I running way too rich? Would the jet sizes cost me almost 20mph? Are these two sets of carbs not interchangeable?

I apologize for all of the questions and the lengthy post and greatly appreciate any help.

Thanks,
Rob

[RaceCarRobbie]

Whoops, I forgot to include the #'s on the carbs. On the 1992 on top of the top carb it said WMH with a 1A perpendicularly above the W and 2 above the 1A.

On one of the 1989 carbs it just had a WH. Other #s located on this same carb were 1374-5427C, 157-155, and 46-10749.

Thanks again for the help.

[Ranger976]

the great T-Rex:eek: answer this one as your now standing in his back yard........:thumbsup: Get ready for the 2.4L GURU.....:D

[j_martin]

It mit hep T-rex to no at what altitude yer runnin dat bote. Oh by the way, line up an interpreter.

hope it helps
John

[T-REX]

Well, don't no why ya bote iz dat much slower slow'er, even wit tha 46's it shouldn't looze that much power...Yo mota may very well be rich, kuz tha ole piston port motas used more fuel than tha more efficient behind tha liner 2.5's...

Put ya wmh's back on and see what happens...Step it up to .068 mains if it makes ya feel better.....066 should be good without sum major mods....My 200 2.5 haz them wmh carbs wit .066 mains, and it turns 6800 all tha time!!!...Plenty of fuel....

U will have to check plugs to see what iz up wit ya 2.5 slow'in daat much...thats tha only way to questimate if it'z tha carbs give'in U tha problem...


Oh by the way, line up an interpreter


Damm John, ain't dat frigg'in bad iz it???:D

[j_martin]

I have to slow down so much to read it that I actually learn something.:D

John

[tlwjkw]

Rex, I think he's got tha 2fo with tha wmh's on tha boat. But I might not be readin' it right. If thats right then tha 82's in tha wmh would suck doncha' think........T

Might wanna take a close look at tha stator.......

[ct20sutphen]

I have 68's in my engines and during break in they put 70's in there to be safe. I also backed off the oil inj and add some oil to the fuel. hope that helps