Sputtering Johnson V4 90hp - 1994

[Berdink]

I have a new to me 1994 Johnson 90hp V4.
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It started real nice and ran real nice when I first heard it run.
When I ran it more at home, it sputtered some off and on.
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I did a strong mix of seafoam to see if that would clear things up.
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It didn't.
I read up on the Link & Sync and got everything adjusted as described.
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But then it progressively sputters more.
It's been awhile since I've worked on engines. My last was a SBC in a 1965 C10.
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Anyway, I remembered the idea to spray carb cleaner around gaskets and linkage and hoses.
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When I spray carb cleaner at the bottom of the upper carburetor, it so slows the idle and smooths out. (see pic) - btw, I was pleased to see I had aluminum fuel bowls and not the plastic ones.
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This tells me I have an air leak.
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I'm going to order a carb rebuild kit and gaskets, but it may just be a leak. I figured if it wasn't just a leak, then I'd still know that I went through the carbs and that at least is good.
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Thoughts?

 

[Berdink]

This kit x2, correct?

 

[racerone]

I doubt there is an air leak.

 

[Berdink]

I doubt there is an air leak.

But it changes idle significantly when I spray carb cleaner near the bottom of the bowl.
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Okay, maybe I should have called it a vacuum leak.
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What do you think the issue is?
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Either way, I bought two rebuild kits. I can check all the hoses, connections, and seals while I have it apart .

 

[Berdink]

I meant to say a vacuum leak.

 

[saltchuckmatt]

What are you idling at in your driveway rpm wise?

Throat of the carb is grabbing some of your carb cleaner...even if the bowl had a seal problem it would just leak.

1100 out of the water

Post compression numbers.

Idles probably to low.

 

[Berdink]

Last time I ran it in a 55 gallon drum cut in half filled well above where the lower unit meets the midsection - probably around 6 inches above the cavitation/ventilation plate.
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I need to get a tach.
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Cold Compression is around 120psi.
120, 119, 121, and 126 PSI

 

[saltchuckmatt]

Last time I ran it in a 55 gallon drum cut in half filled well above where the lower unit meets the midsection - probably around 6 inches above the cavitation/ventilation plate.
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I need to get a tach.
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Cold Compression is around 120psi.
120, 119, 121, and 126 PSI

You can do it by ear....should be high in the barrel and quite a bit less in the lake. As long as it's not slamming into gear when shifting.

 

[Berdink]

I'm going clean the carbs, inspect all hose connections, and check everything over.
It's probably time anyway.

 

[Berdink]

These surfaces look good and smooth.

 

[Berdink]

However, there is some discoloring on portions of the carb mating surface.
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And why doesn't the gasket cover everything?

 

[jimmbo]

If you are referring to the Milk Bottle shaped Opening not being covered by the Gasket, it would be a Waste of Paper, as there is nothing on the Manifold to contact

 

[Berdink]

Yes, I see that. And looking at Google images, the others are the same.
Thanks

 

[Berdink]

Okay

If you are referring to the Milk Bottle shaped Opening not being covered by the Gasket, it would be a Waste of Paper, as there is nothing on the Manifold to contact

Okay, you're of an older generation. Milk Bottle?
I remember the Milk Man and those cold glass bottles in that metal carrier and left on the porch.

 

[Mc Tool]

Okay

Okay, you're of an older generation. Milk Bottle?
I remember the Milk Man and those cold glass bottles in that metal carrier and left on the porch.

And when it was frosty the milk would freeze and pust the foil top off the bottle , and sometimes sparrows would peck holes in the top to get a drink . And milk tokens ...bought at the corner dairy (a dairy is what Kiwi's called small neiboughood shop)

 

[Berdink]

If you are referring to the Milk Bottle shaped Opening not being covered by the Gasket, it would be a Waste of Paper, as there is nothing on the Manifold to contact

That would explain when I sprayed Carb cleaner. The carb cleaner probably went right down that hole.

 

[Berdink]

I doubt there is an air leak.

@racerone , do you think it's just the carbs need cleaning?
Do you think I should check something else while I'm digging into it?

 

[jimmbo]

You said in the Original Post that your last Experience was with SBC. Forget most of what you know about the Chevy, in fact any Car/Truck Engine, as these 2 Strokes are quite different, when it comes to Adjusting.

First Things first, have you done a Compression Test? If No, do one and post the Numbers; if Yes, what were the Numbers?
Is the Spark Strong Enough to jump a 3/8" Gap on every Plug Wire?

Can you verify that there are no Misfires occurring because of Voltage Leaks to Ground, from bad Plug Wires, dirt on or Cracks in the Plug Insulators?( I used to run Engines in the Dark, taking care to stay clear of the Flywheel, looking for Flashes of Light).

If all these check out, I would then start inspecting the Fuel System, Float Setting, Inlet Valve of the Carbs. If the Carbs have an Idle Mixture Adjustment, is it set correctly.
Even when set up Perfectly, most 2 Strokes tend to get a little Jumpy/Twitchy when Idled for several Minutes, as Fuel can Puddle in the Crankcase.

Some things to keep in Mind. Idle Speed is NOT adjusted anywhere near the Carb(s), on these Engines, the Carbs are Fully Closed for the Majority of the Throttle Lever Movement. Only after most of the Timing Advance has happened, do the Carbs open. Idle speed is actually set by adjusting the Ignition Timing at Idle, and there is no Idle Timing Spec.

There is however a Pickup Timing Spec that differs from Model to Model, and that can change from year to year. Checking and adjusting it is part of the Link and Sync

 

[Berdink]

I already started on cleaning the carburetors. I figured since it had been sitting, it's best to anyway.
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I'll likely have things back together this weekend.
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I'll check the things you suggested.
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Cold Compression is around 120psi.

120, 119, 121, and 126 PSI