1991 Johnson 120 V4 Looper Carb Orifices

[Strangeleak]

Hi Everyone,

I have Engine Model VJ120TLEIE with #4 cylinder not firing and an occasional-frequent cough/sneeze at idle that eventually stalls the engine. I've confirmed compression, and the presence of fuel, and spark up to the spark plug(could be fouled). I have ordered new plugs to try soon though.

I was hoping to get some information from someone with the same engine as me. In regard to the two orifices on the front opening of the carburetors for idle and intermediate jetting. On my engine, the "upper" idle orifice has 22 etched into it and the "lower" intermediate orifice has 24 etched into it.

Can anyone with a properly running 120 confirm that this is correct for this engine? Or if larger/smaller jetting is necessary for an older engine.

I have tried searching the web for the correct sizes but have only found numbers for the 140hp model engine of that year for the idle orifice and the intermediate orifice is supposed to be a #27(mines #24) according to another website. But I don't know if that is correct.

Also, what is the standard running position of the primer solenoid valve? Mine can rotate between 12 and 6 o'clock positions.

Thanks,
Nate

 

[Bosunsmate]

I cant answer the orifice questions but the primer solenoid should be inline at 12 o clock when running in the normal operating mode which is when you push the key in to operate it. Having it at 6 o clock is when you are wanting to have it open manually which is never something ive needed to do but handy if you ever needed to do a cold pull start.
Sneeze could be due to lean fuel mixture and the non firing could be by a coil or something more upstream towards the flywheel necklace gear

 

[Faztbullet]

Jetting sounds correct...

 

[Strangeleak]

Oh ok, because the previous owner of the boat had it in the 6 o'clock position. The primer will still activate when depressing the key though and is necessary when it's cold. I guess i'll never need it in the 6 o'clock position then because this engine does not have a pull start. Could running it in the 6:00 position cause excessive fuel consumption/delivery and possibly have flooded cylinder #4 to the point where the mixture wouldn't ignite? After it is running a while there is quite a bit of oily sludge that collects in the exhaust port of the prop.

Bullet, thanks for the reply. I'll cross that off the list of wonders. LOL

 

[racerone]

Running with the lever in the wrong position will dump extra fuel into ALL the cylinders when motor is running.--It does not have a pull start but a hefty individual could start that motor with a rope should there be a dead battery.

 

[Strangeleak]

Update:

Bosunsmate, thanks for the info on how the manual primer circuit works. Though after checking for proper operation, the normal operating position for my particular engine is in the 6:00 position. I flipped it to 12:00 with the primer lines disconnected from the valve body and fuel squirted from each one when squeezing the primer bulb.

I also discovered and solved what was causing my dead #4 and overall poor idle. The 5 wires leading from the stator to the power pack had been repaired by a previous owner. They tried to reuse the amphenol connector which is all well and good, but the wires were so corroded and brittle that the purple wire broke and pulled through the connector. I cut it all out and hardwired in some 12 ga wires, replaced the plugs with the QL78YC, gapped them to .030", and it's running great at idle!

Before I found the stator wires messed up, I also cleaned out the fuel recirculation check valves. After I got it to run I found a corroded ground terminal for the power pack, replaced that too.

I've still got a very slight hiccup/sneeze when holding RPM above idle though. It doesn't do it at idle anymore and the engine doesn't stall. I'm going to test for the lean mixture by partially blocking one carburetor at a time to see if it clears up. I've also heard of people using a toothpick to block/partially block the idle or intermediate jet on the carb face.

Any other suggestions to diagnose a lean sneeze?

Before Fatzbullet's reply, I had swapped the idle/intermediate jets to try and rule it out so in the video it's running a little rich. I changed them back once I realized they were still backwards.

 

[Strangeleak]

No Title

After doing some more research, it appears the carbs on this engine aren't factory. These picture indicates they are from a 1986 200-225hp according to all part's catalogs. If so, what issues can I expect? Can these be jetted to work properly? Disregard the idle jet missing. I had it out during the picture.

 

[Strangeleak]

Also, I wasn't able to get my caliper completely in the venturi throat, but used a set of needle-nose vice grips to "dial-in" the venturi diameter. It measured 1.635" or 1 5/8 which is apparently much bigger than either carb that was offered on these V4 engines. I've read 1 5/16" or 1 3/8" depending if its a 120 or 140 respectively. Also note the 3 screws on the butterfly, as opposed to the 2 screw butterflys that I've read belong on this engine.

 

[flyingscott]

That idle sounds good. Get it in the water to see how it runs. You cannot tell anything by running the motor on muffs.

 

[Strangeleak]

I've got to get it registered first, then i'll take it for a spin.

What's your thoughts about the carb numbers/specs?

 

[flyingscott]

You are not going to know anything till you get it on the water. You cannot tune it in your driveway.

 

[cfauvel]

You are not going to know anything till you get it on the water. You cannot tune it in your driveway.

x2 on having to be on water.

I think you have tuned it as much as you can on muffs.

Its a huge bummer that you have the incorrect carbs on that motor, there will be no way to know which way to go with jetting as the bore is probably not correct for your engine...

if indeed from a 1986 200-225 ( with some research I find part 0395925 as being the upper carb assembly for a 225hp)
the idle air bleed could be #20 (200stl), #26 (200tx only), #20 (225)
Intermediate air bleed could be #42 (200stl), #43 (200TX), #14 (225) (big difference between 43 and 14)
High-speed jet could be 76D(200stl), 57D (200TX) and 65D (225)

good luck....let us know how it goes

 

[Strangeleak]

Cfauvel,

I found the same info you did. Yet my air bleeds are:
Idle #24
Intermediate #22
High-speed 65D

I ordered the original '91 120hp size air bleed (Idle 34 Port & 37 Starboard, Int 27) to change them back to factory, but that was before I realized these bores may be too big for the factory 120 jetting.

I may try to sneak an outing during a weekday, hopefully the "man" isn't out for a cruise that day as well.

 

[cfauvel]

Cfauvel,

I ordered the original '91 120hp size air bleed (Idle 34 Port & 37 Starboard, Int 27) to change them back to factory, but that was before I realized these bores may be too big for the factory 120 jetting.

Yeah best to leave the air jets you have, or buy the 14 and 20 air bleeds....

I have an 86 225 with 87 carbs, the idle and intermediate jets changed quite a bit, most likely due to bore size.

the 86 as you know are 14 intermediate, 20 idle and 65D for high speed
the 87 is 14 intermediate, 48 idle and 62D for high speed.

so a 48 is a bigger air bleed thus leaner than the previous year, by quite a large number, reason? I dunno...maybe smaller bore in the 87 letting in less air thus more fuel, thus needing more air at idle...kind of confusing.

 

[Strangeleak]

so a 48 is a bigger air bleed thus leaner than the previous year, by quite a large number, reason? I dunno...maybe smaller bore in the 87 letting in less air thus more fuel, thus needing more air at idle...kind of confusing.

+1 on confusing, I don't even know how the engineers began to calculate that! And what would constitute such a drastic change on the same HP rating engine from one year to the next? Smaller bore = higher velocity = better throttle response maybe?

All I'm hoping is that between the 16 jets that I now own, I can get this thing to run good. How will I know if i'm running too lean out on the water? i'm familiar with the lean sneeze, will it be more pronounced when under some throttle?

 

[cfauvel]

How will I know if i'm running too lean out on the water? i'm familiar with the lean sneeze, will it be more pronounced when under some throttle?

great question...at idle a lean sneeze will still sound the same in water...but as you go up the RPM, I doubt you'll be able to hear it. As far as running lean at speed, you'll have to inspect the plugs.. If they are dry i would suspect that you are too lean.

Start with the recommend jets, I think your idle air bleed is too large, but not by much. And do a link/synch on the motor...the idle speed is not set by cracking the butterflies, rather it is set by timing. The butterflies NEED to be completely closed so the idle jets do their thing.

 

[Faztbullet]

1) You cannot correctly jet or adjust this motor unless its in the water or in a barrel to supply backpressure. Any attempts to adjust/jet without backpressure is wasted effort.

 

[Strangeleak]

Start with the recommend jets, I think your idle air bleed is too large, but not by much. And do a link/synch on the motor...the idle speed is not set by cracking the butterflies, rather it is set by timing. The butterflies NEED to be completely closed so the idle jets do their thing.

Recommended jets for the 120HP or the suspected incorrect carbs(225HP)?

I currently have the following jets, with the red ones currently installed:

(4) #22's (225HP?)
(4) #24's (225HP?)
(4) #27's (120HP Intermediate)
(2) #34's (120HP Port Idle)
(2) #37's (120HP Starboard Idle)

I did the link and sync so the butterflies are definitely closed. Timing is 95% done. Used the Joe Reeves method to get 14? BTDC at WOT(Supposed to gain the other 4? when actually running, which I'll confirm). Idle timing is close, but i'll set that to 8? ATDC once I'm in the water.

1) You cannot correctly jet or adjust this motor unless its in the water or in a barrel to supply backpressure. Any attempts to adjust/jet without backpressure is wasted effort

I hear ya Fazt, though I'm not really trying to make any adjustment or re-jet, so to speak. At least not with the idea of perfecting the engine operation. Just trying to establish the best starting point for this engine knowing it's a good possibility that it has the wrong carbs on it. Looking for an experienced opinion from someone who may have dealt with this in the past. If I knew the carbs were the correct ones, I wouldn't be worried about it.

I'm really hoping for someone with the same engine to come along and tell me the bore diameter of their carbs, but until then I'll just have to assume they're incorrect and prepare for some on the water tuning.

Thank you both for your time and help.

 

[cfauvel]

Recommended jets for the 120HP or the suspected incorrect carbs(225HP)?

I currently have the following jets, with the red ones currently installed:

(4) #22's (225HP?)
(4) #24's (225HP?)
(4) #27's (120HP Intermediate)
(2) #34's (120HP Port Idle)
(2) #37's (120HP Starboard Idle)

I did the link and sync so the butterflies are definitely closed. Timing is 95% done. Used the Joe Reeves method to get 14? BTDC at WOT(Supposed to gain the other 4? when actually running, which I'll confirm). Idle timing is close, but i'll set that to 8? ATDC once I'm in the water.



I hear ya Fazt, though I'm not really trying to make any adjustment or re-jet, so to speak. At least not with the idea of perfecting the engine operation. Just trying to establish the best starting point for this engine knowing it's a good possibility that it has the wrong carbs on it. Looking for an experienced opinion from someone who may have dealt with this in the past. If I knew the carbs were the correct ones, I wouldn't be worried about it.

I'm really hoping for someone with the same engine to come along and tell me the bore diameter of their carbs, but until then I'll just have to assume they're incorrect and prepare for some on the water tuning.

Thank you both for your time and help.

I would start off with the orifices called for by the 225, since those are the carbs on there....

the smaller air bleeds will make the engine run richer, which should fix the lean sneeze.

other things, as you've found out, would cause the lean sneeze....I found a broken carb distribution manifold that was causing mine....weeks of diagnosing to find it..