Johnson 40hp 2005 link and idle adjustments

[Gemat1973]

Hi,
I recently bought a used J40PLSOC that the previous owner used to repair on his own. Every setting was messed including linkages, needles, floats, orifices.. even the plugs were not the correct model.
After buying the service manual, I reassembled and corrected all the things I find different than the factory suggests.
I made the engine run nicely when idle and I suppose it performs as is should in WOT.
But there are a few settings that I cannot match with the manual or the engine will not work.

1. The manual says that the spark lever roller should be between the arrows of the cam lever when idling . In my case the roller is about 1/4 of an inch higher than the arrows.

2. The manual says that the distance between the Idle adjustment screw head and the spark lever (distance B) should be half an inch. In my case it is impossible to screw it that much. Even at 3/4 the tension of the roller against the cam plate is high so 3/4 is the minimum distance I can go.

3. The manual says that the Idle screw should be about 2,5 turns from fully scewed, but I get smooth idle at almost 6 turns! Nowhere near 2,5. At 4 turns it coughs spits and dies...

I reassembled the carbs carefully making sure everything is clean and in good condition. I was expecting that the engine should work at the factory default settings but my engine works as I mentioned above in different adjustments. All other adjustments like link lengths, orifice sizes are exactly as the manual says.

Is this common with Johnson engines or there is still something wrong that I overlooked?

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Image 455969401-862584838741627-4003972279267195287-n hosted in ImgBB

ibb.co

 

[racerone]

The first thing to do with your motor is a compression test.----Post the actual values here.

 

[Gemat1973]

The first thing to do with your motor is a compression test.----Post the actual values here.

Top cylinder 117, lower cylinder 122, not sure that the engine was fully warmed up. It was idling for about 2 minutes.

 

[saltchuckmatt]

Sounds like carburetion.....air coming from somewhere. Spray something combustible around....could be timing though. Your idle circuit should not be spun out that far.

Did you rebuild the carbs with OEM parts?

Are the plastic carb parts warped?

 

[Gemat1973]

Sounds like carburetion.....air coming from somewhere. Spray something combustible around....could be timing though. Your idle circuit should not be spun out that far.

Did you rebuild the carbs with OEM parts?

Are the plastic carb parts warped?

Yes, I used OEM parts. The top carb plastic cover is a bit warped but the rubber seal appears to be evenly pressed against the carb. If there are air leaks they are too minor to detect. The spark lever position has much more effect to the idle speed than the idling needles with the spring. The idling needles seem to have no effect from 6 turns up to fully unscrewed. But if I screw them beyond 5 turns the idle becomes erratic and at 4 turns unsustainable.

About the big idle screw (see my picture, middle arrow) on the spark lever, I have to unsrew it about 1,5 inches to make the roller go between the arrows. The manual says that it should be between the arrows and be 0,5 inches unscewed... There is no way to match both conditions.....

 

[saltchuckmatt]

Not sure without seeing more. Primer and intake could also be leaking.

I assume when your checking the syncing that the throttle cable is disconnected?

 

[Gemat1973]

Not sure without seeing more. Primer and intake could also be leaking.

I assume when your checking the syncing that the throttle cable is disconnected?

"checking the syncing" ... What do you mean? At what point do I have to have the cable disconnected?
I am Greek so I am struggling a bit with the language....

 

[saltchuckmatt]

Referring to the link and sync of the carburator opening at just the right moment of the timing. The throttle cable should be unhooked until that is achieved.

Not sure how that would make the carb want so much fuel but maybe.

 

[tphoyt]

Sounds like you motor was molested by the previous owner. This may not help but if it were me I would do a link and sync from scratch.
Follow the manual exactly as is written step by step and don’t try to out smart the process.
You may find that’s it all correct but you have to do it to verify that.

 

[Gemat1973]

Referring to the link and sync of the carburator opening at just the right moment of the timing. The throttle cable should be unhooked until that is achieved.

Not sure how that would make the carb want so much fuel but maybe.

My carb’s idle needle handles air, not fuel. So practically it requires more air than normal. About the synchronization of the throttle linkages, I did it from scratch. But when the engine is running idle there is no tension on the linkages. Both carburetors are fully closed by their springs.

 

[tphoyt]

Sounds like you’re pretty confident on your linkage settings. How does the cam roller look?
They can sometime crack and without spinning it around it can hard to see a missing pice of the roller. This will mess with its alignment.

 

[Gemat1973]

Sounds like you’re pretty confident on your linkage settings. How does the cam roller look?
They can sometime crack and without spinning it around it can hard to see a missing pice of the roller. This will mess with its alignment.

the roller was damaged when I got the engine. Only the black core was present . I made a custom one out of teflon. It rolls nicely but the diameter is a guesstimation .... I made it about 95% of the space available... Johnson parts are hard to find here.

 

[saltchuckmatt]

By spinning the idle circuit clockwise it's more lean, by unscrewing it....it makes it more rich, so not sure what your talking about.

 

[racerone]

But there are some idle circuits that are DIFFERENT on outboards.

 

[Gemat1973]

By spinning the idle circuit clockwise it's more lean, by unscrewing it....it makes it more rich, so not sure what your talking about.

That is exactly how it is described in the manual.
In my case if the needle is 2,5 turns from fully screwed the engine does not start. I keep unscrewing and trying and at 4-4,5 turns it starts but does run rough. At 6 turns it runs nicely and there’s no more change even at 10 turns….
Also I don’t understand how unscrewing is supposed to make the engine rich. The needle handles air. It is tapered but not pointy. As I unscrew it it lets more air pass. How does it make the engine run richer?? Is there fuel at the top of the carb??

 

[saltchuckmatt]

Well unless race is about to elaborate more, the carb forms a venture and by letting in more air more fuel is drawn, in this case, to the idle circuit which yes is located on the top of the carb appears to pull from the primer.

Not as familiar with these carbs.

 

[racerone]

???---What---the primer valve is CLOSED when engine is running.----It does NOTHING.----The electric primer is only used for starting a cold motor.

 

[saltchuckmatt]

This particular carb has a primer nipple on top and no draw tube inside the carb....either way fuel going up through the carb is different than I'm used to. Setting are out of spec so something is wrong here.

 

[saltchuckmatt]

Could your needle valve be broken...? Part 18

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=2005&hp=40&model=J40PLSOC&manufacturer=Johnson&section=CARBURETOR

 

[racerone]

The primer valve is only used for cold starts.-----When motor is running it does NOTHING.