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'72 johnson 25 idle

T

tinboatman

Member
I have a question regarding idle on this early 70's 25. The motor will not idle unless the roller is just passed the 2nd mark on the throttle cam. Im not sure if this is normal or if I am advancing the cam too much for idle. Even past the 2nd mark it will occasionally spit and sputter. Also the low speed needle sweet spot is just a half a turn out which I think is strange (note I have rebuilt the carb and this setting continued to be the sweet spot). On top of all this on the throttle cam, roller, and roller linkage there is this tacky black oil which I am not sure where its coming from.
 
Oil ?----Is there a wee rubber oil recirculation hose.----It comes from bottom of block, goes to the top bearing.----Possibly cracked ?-----Throttle plate MUST be closed for good idling.-----Post compression test values here.
 
I already took the hose off and looked at it and it appeared to be good still, compression is around 130 top and bottom. What size hose is it? I might have some laying around to go ahead and replace it anyway. Im aware the throttle plate needs to be closed for it to idle thats why I find it strange why I have to turn it so far to idle. I have cleaned and rebuilt the carb and know for sure the idle circuit is all clean there.
 
Motor needs 4 things to run.-----Correct amount of fuel.----Crankcase compression.-----Spark at the right time.-----Compression in the cylinder.-----So does spark jump a gap of 5/6" , yes or no ?----Tried another carburetor ?-----Checked lower crank seal.-----Is thermostat in place , not stuck open ?
 
I know it jumps a 1/4” gap il check tomorrow to see about a 5/6” gap. I haven’t swapped carbs. How would I go about checking the lower crankcase seal?
 
It will not jump a spark gap of 5/6". When I set the gap to 1/4" it will not jump it on every pull either, like on one pull it will jump but the next pull it wont always jump even when Im pulling on it very hard. What's weird is I have replaced points, condensers, and plug wires because the old wire had a bunch of cracks in it so I am not sure whats causing it. Points were set to .020.
 
I had a similar issue and it turned out that only one cylinder was firing. Glad I figured that out before deciding to tinker with idle settings, timing, etc.
 
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