Help: 1987 Johnson GT 200 Jet confusion

**Krazymaan** · 05-06-2017, 09:50 PM

I rebuilt my carbs and i misplaced all three jets for one carb. I figured no biggie.
Well....
My Johnson 200 GT is a 2.7 Looper (200STL) and only the 87 comes with the medium bore carbs. 1.5" venturis. Which is what I have. I got that, I get it.

So I look at my high speed jet its a No. 67D. I go to boats.net to order and it says my high speed jet for the 200STL for 1987 which is the one i have needs to be a No. 74D and the 225 motor is a No. 62D and the 200TX is a No. 57D SO WHAT DO I DO?

Then I look at my Idle jet and its a No. 35 jet and it says it needs to be a No. 48 jet for the 200STL motor which is mine. Then the 225 motor is a No. 48 and the 200TX is a No. 26. SO WHAT DO I DO?

Then I look at my mid range jet and its a No. 39 jet and it says it needs to be a No. 14 jet (wow that tiny?) for the 200STL which is mine. Then the 225 motor is a No. 14 jet and the 200TX is a No. 43 jet. SO WHAT DO I DO?

What I have and what the book says I need are so far off I need some expert advice. Where should I start out at?

Lets not forget about those 106 pull over tubes. I ordered some but I don't exactly understand them well i sorta do, lean spot between mid and high restricting air flow making highs kick in a few hundred rpms sooner or something like that, I'm going to run my air cleaner, its factory gutted. Finally my heads have been milled down and I run full CDI electrics, not sure if that matters but I might as well tell it like it is.

Thanks.

**Krazymaan** · 05-06-2017, 11:19 PM

i did some further online investigating and if I am not mistaken I have 225 hp butterflies because they have three screws instead of two screws. I read you shouldn't put two screw butterflies with these carbs but they didn't say if it was ok to put these carbs on three screw butterflies. Is my combonation safe how you see it with the 3 screw butterflies, the black medium bore 1.5 carbs and the factory gutted air cleaner and then the 106 pull over tubes that I just ordered. I'll check my compression tomorrow and hopefully someone can steer me in the right direction for jets. All six the same or bottom two different size?

**58Evinrude** · 05-07-2017, 01:49 AM

OMC was pushing stuff out the door so fast, some changes never made it into the books. If they made a change to the carb bodies or the butterfly plates, the jetting changed. I have 5 sets of mid bore looper carbs, on the butterfly plates. All are from 200's, from 88 to 94. All have different jets. If the motor ran good before you lost the jets, I'd be putting the same size back in, and forget what the book says. I tried running the pull over tubes in my 92 XP 200, but it was way too rich. Tried them in my 94 200 Vindicator, and they worked perfect.

Yes, on the open deck blocks, the general rule is to run about 2 sizes bigger in the bottom 2 cylinders.

BTW, thats not a "gutted" air box. Thats stock. If the internal baffle plate was gone, thats considered gutted.

**Krazymaan** · 05-07-2017, 08:33 AM

Actually it didn't run good, the stator melted drips of plastic onto the timer and froze it in place, took me all summer to figure that out. Motor was falling on its face when throttled and took forever to get up to speed. So new electrics were installed a few days ago. A little confusing but i think i got it figured out. Basically you need to change your electrics from 86/87 to 88+ so a few things aren't being used now like the orange wires from the stator and a yellow wire and a brown wire and this goes here now and stuff like that. I'm not smart enough to explain it, but i can follow directions. So i forgot to order the large rectangular intake gaskets so when i was looking things up, thats when i noticed that what I have isn't exactly what the books say i should have. Now i have to wait till tuesday to get my gaskets so I'm just trying to figure out this carbonator thing and trying to make sure the combination that i have is in the realm of things of if its off in left field.
So my 87 is an open deck block? which means what?
I figured as long as my box was hollow, it was gutted, what does a gutted factory box look like? Is it the other box that doesn't have those holes up the sides?

**racer** · 05-07-2017, 09:39 AM

Picture of air box still has the baffle, are you going to leave it? Makes big difference in jetting. How much are the heads milled? Do you know the chamber size? In 1986 when they updated the engines and switched to mid bore carbs they retained the 3 screw butterfly which is not they only difference in the throttle plates. Mid bores run best on 3 screw plates as the 2 screw was really for the small bore 200.

**58Evinrude** · 05-07-2017, 01:31 PM

If you go back to boats.net, you'll see that the carb bodies and butterfly plates are different bettween the 200 STL and the 200 TX. So there's one reason for jets size differences. And where the hell did you find pull over tubes to order from? I found my set on E Bay, no dealers or the factory had them.

**Krazymaan** · 05-07-2017, 06:01 PM

Heads are 45 cc, The chamber depth is 630
Compression was 100psi and climibing. That was with motor not running this year yet. Battery removed and cranking off of charger only. Its not accurate but its a start.
I have pull over tubes on the way, my shroud is factory vented. Do you think i should keep the air cleaner box or skip it? I like to drive hard whenever possible, I ain't no fisherman.

**Krazymaan** · 05-07-2017, 07:51 PM

Here is what the side of my air box looks like. Should I still remove all of the baffles?

Finding a photo of a gutted air box is like spotting a UFO inside your house.

Click image for larger version.

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**frank jackson** · 05-07-2017, 10:21 PM

the holes in the side of the cover are not stock ... in my opinion find a replacement , or gut it and start fat ..

**58Evinrude** · 05-07-2017, 11:15 PM

Yup, didn't notice them. Good eye Frank.

**powerabout** · 05-08-2017, 04:32 AM

I have some mid bores that are smaller than the 3 screw throttle bore and some others that have a taper in them to match the 3 screw size?

**Krazymaan** · 05-08-2017, 02:40 PM

Originally Posted by 58Evinrude

. And where the hell did you find pull over tubes to order from? I found my set on E Bay, no dealers or the factory had them.

I picked up 18 of them. Figure might as well hoard them. I bought all of them.

**racer** · 05-08-2017, 04:34 PM

The TX or 25 inch 200 came with small bores most years. .630 chamber is .045 less than stock for an XP/GT in 86 or 87. Stock mid bore in 87 would have been 74D main (No baffle in air box on 200STL in 86/7) but since your head is cut I would go up to be safe, the pull over with 74 might be ok but would be close. Idle/mid remember these are air jets so smaller is richer, IMO start with what a stock 88 came with as they were mid bore and the book matched what was in the engines, The 86/7 books did not match.