72 Combat engine running intermittently on1 cylinder

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Papagino

After storing my Norton for the last 30 years, I'm trying to get it back on the road. We've rebuilt the carbs, new battery, switched the coils around to see if that changed anything, static timed it, but will only idle on 1 cylinder, when reved up to about 3,000 rpm, the other cylinder will run rough. Any ideas would be appreciated.
thanks
 
Carbs are still plugged with crud, it dosn't take much to plug the idle circuit. Do a search for it, lots of info.
 
Thanks, I used the Bushman site info., very helpful, cleaned the pilot jet w/ guitar wire and air, some crud came out and when I sprayed carb cleaner in the pilot air screw after the cleaning, it came out in a strong jet.
The ignition is the original twin point system, I bought this bike new in 73, so I know no changes were made.
 
take the points cover off the timing cover

get your shop manual and verify, reset the points gaps and ignition timing

you say it may not have been looked at for 30 years, you maybe not be sparking on one side

a quick way to verify this is to take the plugs out, put the plug leads back on and have an assistant ground the plugs against the head while your kick the motor over with the ignition on in a dark garage, you should see both plugs sparking clearly
 
Something else to consider (this has tripped me up on more than one occasion - I'm a slow learner...); a weak ignition can fairly easily jump a standard plug gap that's laying alongside the head, but the greater the air pressure in the plug gap, the more ignition energy is required to jump that same gap. I other words, a fault in the ignition system may not fire under cylinder compression. To prove this out, take a pair of used (not totally fouled) plugs and break the ground electrodes off. Now, use these to check for a spark. The greatly increased gap will more closely imitate the load seen by the ignition system under actual running conditions. If they spark this way, it's probably not the ignition.
 
Mine started right up on the flaky original points, coils and condensers after 40 years. Not to say they can't go bad.

It's certainly something to check. I'd be checking the look of the spark, plus the pilot circuit again. Who knows what's in those 30 year old hoses, filters and tank. I've always found idle problems on one side only are carb problems, which means it's probably electrical?

Dave
69S
 
After 30 years the grease of the original Auto Advance Unit with it's expanding and retracting in the guide slots has dried up but good. Pull the points plate too ,grease bobweight slot-pins and don't forget to oil the felt for the cam that opens and closes the points. Set and retime . New Condensers a good thing. Check wire connectors.
 
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