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1970 johnson 6hp high speed problems

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344mafia

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1970 JOHNSON 6HP, RECENTLY REBUILT AND CLEANED CARB, SET POINTS, GUYS THIS THING IDLES LIKE A DREAM BUT WHEN I START OPENING THE THROTTLE UP IT SLOWLY GAINS RPM 'S. IF THE MOTOR IS IN GEAR IT NEVER EVEN TRIES TO GAIN RPM'S, BUT IF I UNPLUG THE FUEL LINE AS SOON AS THE GAS STARTS TO RUN OUT IT REV'S UP LIKE A DRAG CAR THEN SHUTS OFF.:confused:
 
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Is the nozzle gasket installed ?---------Have you checked for a ruptured diaphragm in the fuel pump.----------Does the primer bulb go hard when you operate it ?--------Sounds like way too much fuel going into the motor.
 
Well guys i starred all night at the carb diagram and come to the conclusion that i cleaned the thing and never noticed that the gasket that goes on the high speed jet was missing, silly me uh. Thanks for all the advice, ill let yall know if this fixes the problem...in my defense this was the first time i ever cleaned this carb the guy before me must have lost it;)
 
That's NOT a high speed jet!

The high speed jet lies in a horizontal position, screwed into the center bottom of the float chamber.
 
Thanks mr.joe, the parts diagram i got from this site calls the horzontal part you refer to as a oriface plug part#315140. But thanks for letting me know. I sure hope this was the problem, ill hit the water for a test run tomorrow.
 
344mafia said:
the parts diagram i got from this site calls the horzontal part you refer to as a oriface plug
Click to expand...

Any jet would be considered an orifice plug, but they are all different in their design and usage... high speed, slow speed, intermediate speed, etc.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay auction at:

http://shop.ebay.com/Joe_OMC32/m.html?_dmd=1&_ipg=50&_sop=12&_rdc=1
 
OK WELL I INSTALLED THE GASKET THAT WAS MISSING, AND JUST MY LUCK IT WONT EVEN CRANK NOW. I PULL ON IT UNTIL I WAS ABOUT TO PASSOUT AND IT ONLY SPUTTERED A FEW TIMES. TRIED SEVERAL DIFFERENT POSITIONS WITH THE NEEDLE VALVE AS DESCRIBED ABOVE AND NO LUCK. BACK TO THE DRAWING BOARD I GUESS..:mad:
 
With that gasket missing, you were drawing fuel straight up that vertical high speed "nozzle".... enough to make the engine fire BUT not run properly.

Now, the fuel has to flow through that "high speed jet" I mentioned. Now, did you clean it as suggested or am I being ignored? :cool:
 
Sounds like the motor is running on one cylinder.-----Remove top plug wire and see if motor will start, yes or no ?--------------Install top wire and then remove bottom wire.---Will motor start , yes or no ?-------Test the intensity of spark.-------Good spark will jump a gap of 5/16" on that motor.----------Do you have spark like that , yes or no.
 
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344mafia said:
I cleaned it three times, trust me there is nothing in the thing..
Click to expand...

Okay, I'm a trusting soul and will assume it's as clean as new.

Now, the engine starts and runs initially via the slow speed adjustable needle valve. Assuming those passageways are clean also, is that needle valve adjusted as per my suggestions in reply post #9? If so, and the engine has compression and spark, it should start and run.
 
I am going to take it completely apart one more time and quadruple check and then if it dont work, i know to send it down to davey jones locker to aggravate him..the needle was tried from 1/2 turn out all the way to 3 turns out, with no luck..
 
How much voltage bites you ?------How much voltage is required to jump a gap of 5/16" or more.----------Drop it off on my front lawn.------These motors are easy to inspect and repair.-----Did 5 of them over the winter.
 
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When i checked the compression it was at 93lbs, i adjusted and cleaned the points to .20 and it would throw a bright blue spark while holding it outside the sparkplug hole. Im going completely back through the thing tonight and recheck everything you all have mentioned, it just baffles me that it idles awesome with out the gasket i mentioned ealier in the post. Wish me luck.
 
You have not answered the question as to how big a gap the spark will jump.----Perhaps you do not understand how important that is in trouble shooting !!!
 
The 1970 6hp model has magneto ignition. The spark gap should be 1/4". The spark should be a strong blue lightning like flame... a real SNAP!

Set the points as follows:

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubbing portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

NOTE 2: Should the cam have the word TOP embossed on the top of it, that is a cam that could be installed upside down and this is simply telling you which side is up. It is not a position where one would set the points.
 
O.k. Thats something i can use tonight, because mine has the word top in it. I know that we did not set the points to the flywheel key but it was close. I will make the nessasary adjustments and go from that point on to the carb inspection and recleaning if need be. Thanks guys, update you tomorrow on my progress.
 
Glory , i set the points to the keyway and the thing ran like a race car..thanks for all y'alls help. NOW CAN SOMEONE TELL ME WHAT THE SPARK PLUG GAP SHOUD BE SET AT..
 
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The spark plugs should be Champion J4C or J6C. Due to the engine's age, the J6C may provide somewhat improved performance.

On either plug, set the gap to .030 .
 
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