troubleshoot help????

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May 4, 2006
hello all, my 73 commando was running slightly erractic at low throttle, not holding steady in 2nd gear (kind of surging) at about 2800 rpm. it ran great at high end. thought i would sync the carbs, and adjust the valves at the same time. it had been 3000 or so miles since either. also noticed the push on connector going to the zener diode was hanging by a thread. so....adjusted the carbs, (using the 3/16 " drill bit method) adjusted the valves, and twisted the 2 brown wires to the diode (is this okay?) and sodered them to a new connector. when i started the bike it idled okay, but missed when i revved it up. a quick test run and it ran like crap, missing, popping, some backfire, not nearly like it ran before i started. it was running on both cylinders. so i did it all again, found a couple of valves alittle tight, redid them, had 12.8 volts to the zener diode (is this correct?) started over with the carbs. (i had also cleaned and re-oiled my k&n air filter.) with most of the weekend gone, i went mt. biking. tommorrow i will try again. my question is, if the valves are not right (i followed the norton workshop manual ie. when the left intake is at the top of its stroke, adjust the right to .006 same sequence with the exhaust but .008) would it have those symtoms? the carbs seemed synced? if the exhaust valves were tight and i ran it 5 minutes could i do damage? i have adjusted the carbs and valves before and had no problem like this. am i missing the obvious? i am not experienced mechanic but can follow directions. sorry for the rambling, but this is the first time i could not ride my bike away after working on it. thanks in advance to any who answer. cheers, jerome
What happens if you give it a little choke while it's playing up?
Check the kill switch. Dismantle it, clean the contacts, re-tension the phosphor bronze spring contacts ect. Study it carefully so you understand the layout. They can give you all kinds of grief- misfires and backfires being typical.
thanks for the replies. cash, i have never used the choke, although it is there and intact. i will try it. scim, the kill switch was fine before i did the work on it. i was trying to find out if improper valve adjustment or the wire to the zener diode could cause these symtoms. is it just a coincidence that something went south (kill switch) while i was working on it? the hardest thing to accept is how good it ran before i touched it :cry: i will keep at it. any way to determine if it is the kill switch without taking it apart? thanks again, jerome

Hi its my belief that v/v adjustment is not the cause of engine misfire, bad idle, running rough etc, sounds more like fuel. When timing and v/v's are set correct very little if any adjustment is required to maintain aside from checking. If you have to adjust frequently somethings up. If your bike was running good before maintenance and then you develope a {condition} my bet would be double check your work.It would't be the first time I have disturbed one thing while working at something else. I think we all have had similar troubles regards Doxford
thanks doxford, round 3 today. i found out i was being dyslexic with the valves, i am surprised the way i described my method nobody called me on it. anyway, they were all very loose. i was encouraged! took a peek at the carbs again and they still seemed synced. the plugs looked rich, not quite fouled so i replaced them. it ran better but still not right. a definate miss. it seemed if i screwed the air screws in towards rich it ran better. just cannot seem to smooth it out. like i said, it ran fine before my touch? one other mention, i had a small leak from the primary, i had switched to atf this season, and after the first time i ran it after the faulty matenance, it seems to be leaking quite abit more, from where the case meets the engine? as always, any input appreciated. the sun is shinning and i am losing sleep. my smpathy to all who are missing out on riding.....jerome
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