Carb. adjustment

[SUBWAYJO]

I have a pair of 1994 200 HP Johnson V6 Ocean Runners. Can someone give me the procedure for adjusting the low speed needle valves on each Carb. Thanks Joe

 

[ob]

Re: Carb. adjustment

First I would begin by lightly seating each of them(clockwise) and count the exact turns it takes to do this.Then reopen to original setting after noting what that carb is adjusted to.This will give you a reference as to whwere they are now.The final setting that each setup runs at its optimal will vary from engine to engine slightly.An initial into gear from neutral or slow troll will challenge the criticality of idle mix screw settings the most.I suspect that yours will be set anywhere from 2- 3 turns open when checked.With no reference at all 2 1/2 would be a good starting point.<br /><br />Are you having problems with slow speed operation or stalling?If so ,it could be due to improper mix setting or fouled carbs.If it has recently run fine at all speeds at the current setting of the mix screws,I doubt it needs adjusting.

 

[SUBWAYJO]

Re: Carb. adjustment

This engine wot was 500 rpm lower than the other an engine spark test showed no spark in one cylinder, I replaced the ignition coil,replaced plugs, wires and decarbonized the engine. when I removed the air box to spray the engine tune into the carbs I found two of the needle valves had worked themselves loose, I replaced them and set them to four turns ( the same as the other carbs) <br /> since then this engine idles very low (400 RPM) and the lower unit is black with soot. the engine stalls when put into neutral. I ordered a Carburetor synchronizer and am awaiting delivery, it installs into each veturi.

 

[ob]

Re: Carb. adjustment

Might also want to perform a compression test and post the numbers.Inspect each sparkplug and see if the residue and wetness are consisitent.4 turns may or may not be a bit rich as well.Wouldn't hurt to lightly seat all of them and back out 3 turns for a starting point.But wait and see what each plug looks like after a idle run first.<br /><br />Is the other engine of your twin setup opened at 4 turns on the mix screws?Just wondering.

 

[SUBWAYJO]

Re: Carb. adjustment

OB, Thanks for the advise, I will perform the Compression test and inspect each spark plug and post the results on monday. Happy New Year, Joe

 

[seahorse5]

Re: Carb. adjustment

There was a mid-year change in the carbs that year. The adjustment depends on the last letter on your model number.<br /><br />If it ends with a "K", then you have the air bleed adjustable jets, and the "C" or "M" models have the fuel adjustable jets.<br /><br />Air adjustable jets are usually set between fully closed and 2 turns open. There are holes in the air box to reach them.<br /><br />The fuel adjusting jets are between 4 and 6 turns open and you have to remove the air box cover to access them.<br /><br />What is this carb synchronizer that you ordered? The way the throttle plates and shafts are designed, no special tools are needed to sync the carbs like motorcycles, 4-stroke outboards,etc. need to have.

 

[SUBWAYJO]

Re: Carb. adjustment

Thanks for the info Seahorse, My engines end in a K and I have adjustments thru the air box, what your telling me makes sence, the instructions on the air box say (turn counter clockwise for leaner and clockwise for richer) if this was a fuel adjustment it would have to be the opposite.<br /> The syncronizer I ordered from JC Whitney (SL8822792N) fits into the Carb. venturi, it has a direct reading dial and can be used on all types of carburetor's, side draft, down draft, up draft. it will only test one carb at a time. I figure once I have the engine running pretty decent, I can select one by looking at the condition of the spark plugs, get the reading of it's Carb. with the syncronizer and adjust all the others to the same reading. I will do what ob suggested on monday and then readjust the carbs. and post the results. Thanks again and Happy New Year, Joe

 

[seahorse5]

Re: Carb. adjustment

OK, I believe that synchronizer is for the throttle opening sync that motorcycles, older sports cars, and old Volvo stern drive engines with multiple carbs needed to get the same flow thru each carb. A common brand was called Uni-Syn which I still have one from the 1970's.<br /><br />It won't help you with your particular outboard since your engine idles with all the throttle plates completely closed.<br /><br />With a $49 digital Tiny Tach, you can set the air bleed screws on each carb to the highest rpm and then you are done, if you want to get it that precise.

 

[SUBWAYJO]

Re: Carb. adjustment

Seahorse What I don't understand is why I'm running so rich with all the air bleeds set to 4 turns open, it should be lean, when I look at the lower unit It's covered with exhaust soot and I stall when going to neutral(400 RPM) Joe

 

[seahorse5]

Re: Carb. adjustment

Most likely you have flooding carb(s), high float levels, internal leaks, etc.<br /><br />Make sure thermostats are warming up both cylinder heads to 125-145 degrees.<br /><br />Idle timing should be around -8 (8 ATDC) or thereabouts.<br /><br />Test each recirculation valve, hose, and fitting.<br /><br />Decarbon the engine to free up stuck rings. You may have to do this more than once.

 

[SUBWAYJO]

Re: Carb. adjustment

Seahorse<br />I did a compression test, readings are from top to bottom, PORT SIDE 95,95,85, STARBOARD 98,98,92. the condition of the plugs showed that they were wet , I cleaned them with a brass brush and after a warm up, reset the carbs to 2 turns and the engine stalled, 5 turns seems to be the majic number, the rpm came up to 950 ( out of water in neutral) she seems to be OK. will have to sea trial to know for sure. I appreciate all your help and the help from ob. Thanks Joe

 

[ob]

Re: Carb. adjustment

Glad you got her adjusted and seahorse steered you in the right direction on the air needles.I was thinking fuel mix screws.Hope the watertest is a success.

 

[seahorse5]

Re: Carb. adjustment

Might as well get new carb kits and go thru them completely. Sometimes the side cover gaskets (black ones are old style) can swell and restrict the air passageways, causing a rich idle condition also.<br /><br />Make sure the idle and midrange air bleeds are the correct size, and that they have not been mixed up or changed.