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1988 Johnson 50 VRO

L

lpstudio

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I was winterizing my outboard this weekend it was about 2 celsius and I had a bugger of a time trying to keep it running so I could spray in fogging oil. The strange part is with the fast idle up about a 1/4 to half way if I sprayed the top carb the engine would rev up to where I would expect it to run. Spraying the bottom carb didn't do that at all. after it was finally warm enough to run without fast idle spraying both carbs slowed the engine down like one would expect. I am wondering if I am chasing a leaking seal or maybe the top cylinder is starving for fuel?

I rebuilt both carbs but forgot to run a small wire in the the middle tube I think is from the main jet. I just bought the boat this summer so it is all new to me.

Thanks in advance
Ron
 
No----The main jet ( aka orifice plug ) is in the very bottom of the carburetor bowl.----Remove the drain plug first.-----Also do a compression test on it.---Also does spark jump a gap of 3/8" or more on both leads , yes or no ?
 
Hi thanks for the reply I have done all tests above. Compression is 130ish per cylinder, I did carb kits but didn't stick a wire in the small tube in the center. I did spray carb cleaner through it however. I also changed the power pack so I did all the spark troubleshooting.

I think I am going to take the top carb off in the spring and re clean it not forgetting the wire trough the orifice's. I was just worried about a lean condition.
 
The small brass tube that sits vertical and offset within the brass main high speed nozzle... the one you speak of that has a very small passageway hole... is the slow speed fuel passageway.
 
If that was blocked a bit would that make acceleration a bit boggy? I have to feather the throttle at times to get it to rev up mainly when it is cold.
 
lpstudio said:
If that was blocked a bit would that make acceleration a bit boggy? I have to feather the throttle at times to get it to rev up mainly when it is cold.
Click to expand...

If the idle is normal, that small tube is usually clear.

Having the engine bog down when throttle is applied is normally caused by a (1) Restricted High Speed Jet, a (2) Sticking Timer Base, or (3) the Throttle Roller opening the throttle butterfly(s) in relation of the timing.

It's usually the fault of a clogged high speed jet that located horizontally in the bottom center portion of the float chamber... way in back of that drain screw.... BUT... do not overlook the other causes!
 
I am going to do a link and sync in the spring to make sure everything is setup correctly but does anyone think I have an air leak due to the fact the engine revved up when I sprayed fogging oil into the top carb?
 
An air leak?... No!, It is more likely that the high speed jet is restricted. Fuel must flow through that jet freely before it can gain access to any other fuel passageway. Spraying anything combustible into the carburetor's throat would increase the rpms in such a condition.
 
joereeves said:
An air leak?... No!, It is more likely that the high speed jet is restricted. Fuel must flow through that jet freely before it can gain access to any other fuel passageway. Spraying anything combustible into the carburetor's throat would increase the rpms in such a condition.
Click to expand...

Ok my coworker who used to be a mechanic said I should look at the top crank seal could be sucking air causing a lean condition. I think I will take that carb off in spring and clean it again.
 
Your co-worker does not know how reliable the top seal is !!----Have never seen a bad one on a 2 cylinder motor like yours.----Find and clean the high speed jet in the bottom of the CARBURETOR BOWL before doing anything else.
 
If it was run lean for any amount of time, you should check compression. If the upper cyl is more than 10 pounds lower then there could be some scoring started. You will have to monitor compression in the future to see if its going downhill. Its always top cylinder it seems, but if the lower carb partially plugs, like a Yamaha I have here, it will score that just as easily. A crank seal can fail on this motor but it is uncommon. Only seen 2 which I caught and replaced, both on 8 hp with the brown colored lip. When you step back to the 9.5 hp motors, I've saved dozens of them from the boneyard. Ethanol is terrible on the old rubber composition seals. The 9.5's use the same seal up and lower.
 
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