1977 Johnson 55hp stalls at idle and won't rev over 1200rpm

Chevyls6

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Oct 11, 2019
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The last couple of Months there has been a Tsunami of owners trying to adjust 'Idle TIming' and fiddling with the sync between spark and throttle in an Attempt to set the Idle speed. And it gets a little tiring/frustrating

Most 3rd Party Service Manuals are not even good reading material for the Outhouse, and the paper is too slippery to use as Wipes.
Since there are often changes from year to year on engines, a model specific service manual is really the only way to go as it will explain what every adjust screw/threaded rod is for.

If the carbs are the same size(venturi bore, as well as throttle bore, it doesn't mean the fuel flow calibration will be correct before or after a Jet swap. If the carbs came from a 50 HP or a 60 Hp, the calibration may have been different because of differences in Exhaust Tuning(again, what applies to 2 stroke engines is different than to car/truck engines), Off Idle fuel delivery could be different, etc etc etc.

It was mentioned above about a Displacement change, that happened in 76 when the 41 cubic in. 50 hp became a 44 cubis in. 55 hp. In 1980 the 55 hp was upgraded to 60 hp, same displacement(internal changes though)

Factory manual has been ordered from eBay. The block has a plug with 55el77d on it so definitely a 1977 block. 2 strokes are a new thing to me other than repairs on small single cylinder weedwackers, leaf blowers, etc.
 

Chevyls6

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The engine in this video looks just like mine. All the linkages are the same.
 

flyingscott

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The screw with the rubber bumper on it is for max timing. To time it using the joe reeves method it is -4 degrees. That means you subtract 4 deg from the max timing # when you are using the starter motor.
 
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Chevyls6

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Oct 11, 2019
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Ok so i looked into the parts that the original carbs need and wow they are ridiculous. $40 for each throttle shaft and $20 for the choke shaft thats available with the other one being nowhere to be found. All 4 are bad because the chrome plating is flaking off and jamming the shafts in the casting. Anyone have the 387917 and 387918 carbs that theyd be willing to sell? Rebuilt ones are around $300 on ebay but if thats what its gonna cost im better off putting it toward a new motor.
 

Chevyls6

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Alright since the last post I've replaced the carbs with the correct ones and the spark plugs with the factory champion l77cj4. Now it tries to start but stalls. I've got no spark on cylinder one. What could cause this ? Stator is brand new and so are both coils. Power pack and rectifier were done by the previous owner. Carburetors are synced to each other and the throttle can is synced to the roller. I do have the factory manual now but it says to use ignition testers that I don't have.

At this point I'm beyond frustrated.
 

racerone

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Dec 28, 2013
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Test the sensor coils.-----Any testing done before replacing the other parts ?------Throwing parts at a motor gets expensive.
 

Chevyls6

Petty Officer 2nd Class
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Oct 11, 2019
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ok sensor coil is 15 ohms between terminals and infinity from each lead to engine ground. I had originally used cdi electronics troubleshooting guide but for some reason the website wont let me view it now.
 

Chevyls6

Petty Officer 2nd Class
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Oct 11, 2019
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Ok i swapped the orange coil wires on the power pack according to the cdi electronics troubleshooting guide and cylinder 1 still has no spark. swapping the timer base wires also had no affect. I ordered an analog voltmeter from amazon to check for peak voltage values since this parts swapping is getting me nowhere. Oh i also tried the original powerpack from 1977 and that didnt change anything.
 

Chevyls6

Petty Officer 2nd Class
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Oct 11, 2019
Messages
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update: i got the dva in the mail today. stator is sending 310v to the power pack and the timer base is reading 3v lead to lead. I get no power at all at the timer base terminals on the pack with the wires disconnected. Bottom cylinder jumps the 1/2" spark gap but nothing on top. Does this mean the pack is dead?

If so could the old stator have killed it? I also used an inductive tachometer wrapped around the no 1 spark plug wire. Do these pose any danger to the power pack?
 
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