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Since installing the '79 carbs I've been starting the bike several times a day, idling and warming up to full temperature and generally just sampling the rebuild work and set-up. I'll be keeping the '79 carbs on the bike ! Over all everything is good but those little voices in my head resulted in a discovery. I removed one air-screw c/w spring from the '79 and '80 set. Then replaced both screws only. The '80 with a new "O"-ring gave noticeable resistance when turning in and out. The '79 with the 35 yr old "O"-ring had virtually no discernible resistance. The "O"-ring was not making sufficient contact with the bore. The idle-air needle "O"-rings which are the originals (35 yrs) despite looking perfect have shrunk and were bleeding air which created the arrhythmia's I was hearing. I reverted to a former trick I mentioned in an earlier thread and made "quad"-rings from model engine silicone fuel-line. The difference in several aspects was evident enough to myself that changed-out the new "O"-rings on the '80 carbs with the silicone ones. The seal is superior, the material is readily available and inexpensive. In this application the silicone-seal does not come in contact with fuel so it should for all intended purposes, last forever.

The tool I made to remove and re-install the fuel-line with the fuel-valve barb also removes spark-plug boots, I've discovered !