1988 Johnson 120 Secret Carb Orifice

[Pokertrampp]

I have a significant mis on my 1988 Johnson 120, I have been trying to figure out what is causing this issue, well tonight I was double checking it and decided to start the motor, of course the battery was dead so I had to charge it first. Then I did my usual start up routine and the starter would spin the motor and then stop and then spin it again it was like I would let go of the key and then turn it again, strange. But anyway I finally got it running, and of course it still had the mis, I have rebuilt these carbs 3 times soaking the aluminum bases and blowing every hole I could find out with compressed air (these are the plastic carbs on an aluminum base) also I replaced the gasket for the carb base on the first rebuild but have used it again and again with each rebuild, it has a slight tear in it not sur if it could be the cause. tonight I was watching it running rough and it was just like it was a carb issue so I got my little spry bottle of mix gas and began spraying it into the carbs one at a time, and on 2 of the carbs it would significantly change the way it ran the mis did not totally go away but I think there is something going on. Is there a hidden orifice in these carbs that I may have missed? Could there be something else, I have inspected the reeds as well as I can without removing everything and the look to be in pretty good shape. Also the charging system is not working, I am still waiting for the new rectifier to arrive, it should still be able to run normally without a working rectifier, correct? I am also wondering if maybe the fuel has gone bad or something. I am almost certain it is not an issue with the carbs themselves because I have an extra set of carbs and the motor runs the same no matter which set I put on, but I guess anything is possible. all electronics check out with the exception of the rectifier, what else can cause a mis that is there throughout the rpm range, and oh yea, compression is above 100psi on all cylinders. Sorry for the long post, just trying to get it all in so I can resolve the issue. Thanks!

 

[Pokertrampp]

Re: 1988 Johnson 120 Secret Carb Orifice

???

 

[ezeke]

Re: 1988 Johnson 120 Secret Carb Orifice

Is the air silencer on with the correct gaskets? The loopers can't run correctly with them off.

 

[Pokertrampp]

Re: 1988 Johnson 120 Secret Carb Orifice

Is the air silencer on with the correct gaskets? The loopers can't run correctly with them off.

No, currently the air silencer is off because I am still troubleshooting the carbs ect. How can you adjust the carbs and timing with it on, on my motor it is not accessible with it on.

 

[ezeke]

Re: 1988 Johnson 120 Secret Carb Orifice

The engine does not have to be running to synchronize the carburetors or to set the timing statically. But the cover needs to be on for normal running or the engine will run lean.

See: http://forums.iboats.com/showpost.php?p=1969943&postcount=20

 

[Pokertrampp]

Re: 1988 Johnson 120 Secret Carb Orifice

The engine does not have to be running to synchronize the carburetors or to set the timing statically. But the cover needs to be on for normal running or the engine will run lean.

See: http://forums.iboats.com/showpost.php?p=1969943&postcount=20

According to link you provided, it only matters when the motor is under a load. I have not put it under a load only idleing on muffs and it spits and sputters. I have put it a little above idle for a moment or two to see if the mis goes away as rpms are increased ( it does not) but i never put it in gear. my rectifier arrived today and i puchased an intake gasket set and I plan to remove the reeds to completly inspect them with the hopes of find the problem. if there is anything else I should watch for as i tear into it let me know. thanks again.

 

[tashasdaddy]

Re: 1988 Johnson 120 Secret Carb Orifice

you have 3 jets, http://shop2.evinrude.com/Index.aspx?s1=429c8fdd776bb2399ec4b10b79b86499&catalog_id=0&siteid=1

timing http://forums.iboats.com/showthread.php?t=228183

 

[ezeke]

Re: 1988 Johnson 120 Secret Carb Orifice

you have 3 jets, http://shop2.evinrude.com/Index.aspx?s1=429c8fdd776bb2399ec4b10b79b86499&catalog_id=0&siteid=1

timing http://forums.iboats.com/showthread.php?t=228183

Don't try to set the timing on your engine without first disabling QuikStart or you will burn a piston.

The point of my earlier post is that the engine will not run correctly with the air silencer off the carburetors; load or no load, idle or otherwise.

 

[Pokertrampp]

Re: 1988 Johnson 120 Secret Carb Orifice

Don't try to set the timing on your engine without first disabling QuikStart or you will burn a piston.

The point of my earlier post is that the engine will not run correctly with the air silencer off the carburetors; load or no load, idle or otherwise.

How do I diable the Quick Start, I have found numerous threads stating it must be disabled invluding the one from Joe Reeves in the Secret file sticky. but I can not find anything that says how to disable it.

 

[ezeke]

Re: 1988 Johnson 120 Secret Carb Orifice

The temperature switch disables QuikStart when the engine reaches 96 degrees; it does this by grounding the black and white wire. To disable QuikStart, disconnect the Black and white wire and ground the powerpack end of the wire to the engine block - keep it grounded while making adjustments.

You can test this approach by starting the engine with the wire disconnected - QuikStart will engage; then ground the powerpack end of the wire and you should hear and feel the engine slow down as the timing advance is released.

 

[Pokertrampp]

Re: 1988 Johnson 120 Secret Carb Orifice

I have put the "Air Silencer" back on, still runs bad. I had to replace the rectifier/regulator due to battery not charging, but the charging system still does not work, still shows 11.79 volts when running. could this problem with the charging system also be contributing to the poor running of the motor?