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1978 XS - Cold left cylinder/Hot right cylinder
- Thread starter Atxrider
- Start date
I have a '78. Left pipe was hot right cold. took carbs off and had another go at the butterfly sync. Then right pipe hot left cool but not cold. Also had an air leak in the rubber flange between the carb and head. Filed head at inlet flat and surface sanded the flange and used sealant. Happy with results. Good luck.
Alright guys, so here an update.
-Carbs are good, clean and tuned (I know this because of the bellow test)
-Compression is at 150PSI on each cylinder
-Set the timing perfectly with a timing strobe gun; Both cylinders are getting spark, but the left seems to be weak/not firing; I put my hand behind it and it doesn't feel like it's putting out any pressure where as the right blows my hand back
-Did the test again with rotating the advanced rod 180º now that I set the timing perfectly and the left fires strong and the right cylinder is weak; Left cylinder is putting out a lot of pressure and the right isn't.
I am currently awaiting a new dwell for the Pamco to rule that out, but something else I had noticed was that my high output coil is only grounded on one end...and my suspicion is that with that one not being grounded, I have enough of a ground to have spark both spark plugs but only give one it's power stroke...? Am I crazy or could this be a thing?
Ideas?
-Carbs are good, clean and tuned (I know this because of the bellow test)
-Compression is at 150PSI on each cylinder
-Set the timing perfectly with a timing strobe gun; Both cylinders are getting spark, but the left seems to be weak/not firing; I put my hand behind it and it doesn't feel like it's putting out any pressure where as the right blows my hand back
-Did the test again with rotating the advanced rod 180º now that I set the timing perfectly and the left fires strong and the right cylinder is weak; Left cylinder is putting out a lot of pressure and the right isn't.
I am currently awaiting a new dwell for the Pamco to rule that out, but something else I had noticed was that my high output coil is only grounded on one end...and my suspicion is that with that one not being grounded, I have enough of a ground to have spark both spark plugs but only give one it's power stroke...? Am I crazy or could this be a thing?
Ideas?
So, newest update.
-Bought ground clamps from home depot and installed; Same issue persists but good to rule it out
-I tested another theory by removing the plugs, grounding them, and freely spinning the Pamco Dwell. It appears that both sides are sparking when the same one single magnet passes the pickup. Pamco Pete, does this sound right? Or does it back up the suspicion of a dwell with poor polarity in a magnet?
Im hoping the new Pamco Dwell will resolve the issues because Im running out of ideas for probable cause on this.
Also, just out of curiosity, does anyone know if the high output coil would be able to provide spark to both sides like it does right now if it was damaged?
Thanks again for everyones input and help to resolve this
-Bought ground clamps from home depot and installed; Same issue persists but good to rule it out
-I tested another theory by removing the plugs, grounding them, and freely spinning the Pamco Dwell. It appears that both sides are sparking when the same one single magnet passes the pickup. Pamco Pete, does this sound right? Or does it back up the suspicion of a dwell with poor polarity in a magnet?
Im hoping the new Pamco Dwell will resolve the issues because Im running out of ideas for probable cause on this.
Also, just out of curiosity, does anyone know if the high output coil would be able to provide spark to both sides like it does right now if it was damaged?
Thanks again for everyones input and help to resolve this
ippytattoo
Just another grumpy old hack.
If you have spark to both plugs when just one pair of magnets pass over the hall effect sensor then I would say that the coil is good but one of the magnets in the rotor is weak, missing, backwards or the wrong polarity. Pete will chime in soon enough with a more definitive answer but I believe the replacement rotor will fix you up.
Try shooting an induction-clamp timing light at the Pamco Dwell while it's spinning. Either with engine running or someone spinning it from the backside with a cordless drill. Need to go slow. Looking for perceived differences in the magnet positions for right side versus left.
That is, shoot timing light at it while clamped into plug wire, and study the flashed image of the Pamco rotor...
