Inline 6 High Speed Jet removal

**frostydevil** · 05-13-2009, 07:02 AM

Ok, is there a trick I don't know about? How do you get these darn things out without ruining them? I've got a '76 115hp and the one in the top carb seems frozen in there. Theoretically speaking, (lol), if you would happen to ruin the slit where the screwdriver is sposed to catch, how would you go about removing it?

I am about done with these carbs and have purchased a set from a '79 90hp. Ive been through everything and still can't seem to get the bottom carb to run right. The high speed jet is sposed to be .072 according to my Seloc manual, and the jets that are on a '79 90hp are @ .074. Will I be better off just leaving the larger jet size in, or should I put whats supposed to be in there? My local Mercury dealer has three .072's in stock on hold for me, but if I can help it, I don't want to screw with trying to remove them on my newer carbs because they are so darned hard to remove. Your opinions are greatly appreciated, I love this site!

**MERC SCREAMER** · 05-13-2009, 07:11 AM

Make sure that the screwdriver fits the jet perfectly. Once the jet is loosened, use a Round
Toothpick to remove (or replace) the jet. You can actually start the jet into the threads with the toothpick when installing the jets.

I'd try the 0.002" larger jets to start, the ones I presume that are in the Carbs at present. A slightly rich mixture is desireable, and safe!

Good luck. Dave

**frostydevil** · 05-13-2009, 07:46 AM

Thanx Screamer. Thats what I thought. I havent got the carbs in my hands yet, (being shipped), but I hope those are the jets in there (.074's). Unless the motor was from a higher elevation, thats whats supposed to be in them. I am just preparing for the worst I guess. Think I'm going to have to go shopping for the "perfect" screwdriver as well if I do have to change them. I think I will run .074's now regardless. I had some detonation issues when testing this pain in the butt prob over and over again, not being able to get my carbs running right and I want to carbon up the top of my pistons a bit.

**LightNBug** · 05-13-2009, 08:09 AM

When you find a screwdriver that fits the jet properly, try tapping the screwdriver with a brass hammer(like driving a nail) after it's seated firmly in the jet. I've been able to remove many damaged and stuck jets using this method. If the scew slot is too damaged, then an easy-out is about the only way.

**Jeff_G** · 05-13-2009, 08:20 AM

Don't think about running the 90hp carbs on a 115, while they will bolt up they are not compatible. Your engine will go boom.

**frostydevil** · 05-13-2009, 08:35 AM

They are the same except for the high speed jets. WMK series. why would my motor go boom?

**frostydevil** · 05-13-2009, 08:45 AM

The carbs on my '76 115 are WMK 18-1,2,3
the carbs on the '79 90 are WMK 23-1,2,3

same style, same everything I believe (cept a richer jet size). Please explain...

**Jeff_G** · 05-13-2009, 10:02 AM

90's use a choked down carb. Compare the plastic venturi, the main nozzle size, and throat. The model designations for the different carbs are because of differences in the carbs themselves, not just the jet sizes. I have even found differences in the idle tube sizes. Pay particular attention to the id of the venturi and the ID and how far into the venturi the different main nozzles go.

**specboatops** · 05-13-2009, 10:06 AM

Originally Posted by frostydevil

They are the same except for the high speed jets. WMK series. why would my motor go boom?

Listen to Jeff G, guy know's his stuff!

**frostydevil** · 05-13-2009, 11:38 AM

Oh boy, Anyone want to buy a set of 90hp carbs w/ linkages? lol

**LightNBug** · 05-14-2009, 08:24 AM

Originally Posted by frostydevil

Oh boy, Anyone want to buy a set of 90hp carbs w/ linkages? lol

If I had a 76 1150 that needed a set and the price was right, I'd buy them.

**frostydevil** · 05-14-2009, 10:08 AM

If you had a '76 1150 that needed a set, you wouldnt want these 90hp carbs I've been told in this thread. I am wondering though, are the covers (float needles, seats, and floats) the same as on a 115?

**Jeff_G** · 05-14-2009, 10:20 AM

When you get the 90 carbs, check the throat size. If they are the same you can change over the main nozzle, venturi and jets from your 115 carb.

**frostydevil** · 05-14-2009, 10:28 AM

Ok, sounds good. I will bring my calipers home then. Going to be interesting to see the differences, thank for this timely advice. I would have swapped em when they come in without even thinking twice. I had a '71 1150 couple years ago and swapped the carbs with a '73 150hp and it purred like a kitten, smoother than a baby's butt. Just trying to figure this motor out, carb covers are diff and other small variations. Just cant seem to get it to run right no matter what combination of parts I am using (referring to needles and seats).

**LightNBug** · 05-14-2009, 02:14 PM

What I haven't ask, is what is wrong with your original carbs? I've repaired many of these carbs and have never seen one that couldn't be repaired unless it was physically broken. I think repairing yours would be a better way to go. I wouldn't hesitate to use the ones from the 90 as they are. Of course make a short run and check the jetting, but I don't think you would need to change anything. The reason for the main jet difference is due to the metering circuits in the carbs being different. That being said, don't move parts like main nozzles or idle tubes from one carb to the other. If that's done then you have no idea what jets to use.

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