I need SERIOUS HELP!! cylinders 2-3 run and 1-4 only pop

tccook

tccook

Active Member
Hello everyone i need serious help I have been building a 79 cb750 super sport for the last 8/9 months. i was finally able to get it fired up the other night it will idle only on two cylinders and revs but pops at idle like a shot gun it driving me nuts. I have cleaned and swapped plugs, coils,spark boxes double checked for spark witch i have on all four wires. The carbs have been cleaned professionally but i double checked to be sure, the plugs come out wet so I'm getting fuel i have 150 psi in all four cylinders ohmed out all my wires they are good the connections are all tight. ran a second ground two the coils and a wire from the battery to the coils just incase it wasn't getting the right amount of power. I have also disconnected the power wire to the 2-3 coil and left the 1-4 coil hooked up it will only pop a little trying to start it at an idle but if i open the throttle just a bit it quits popping. Could my cam timing be off just a tooth to not allow 1-4 to run?
 
Sounds like you tried everything. I would say it sounds like bad plugs, but you said you've already swapped them. Have you checked the degrees on your timing to see if it's advanced or retarded? It may just be a matter of a degree or 2.

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I have the electronic pick up coils on the crankshaft set exactly how the Manuel says to. And the advancer is working properly. I could loosen it and move it a bit and see if I get any change.


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check your pulse gen connector make sure the wires are not frayed at the plug and shorting

do a pulse generator test yellow to yellow 530 ohms plus or minus 60

blue to blue the same

none of the wires should have continuity to ground
 
cxman said:
check your pulse gen connector make sure the wires are not frayed at the plug and shorting

do a pulse generator test yellow to yellow 530 ohms plus or minus 60

blue to blue the same

none of the wires should have continuity to ground
Click to expand...
Thanks I will get on that as soon as I get home from work. But if it doesn't ohm correctly will it cause the spark to be late ? Because on my light it appears to be 90degrees off I can't tell if it's retarded or advanced


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I got it !!! It runs so good now. I was screwing with the wrong igniter box but


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