- Joined
- Dec 8, 2017
- Messages
- 144
Finally got a chance to start my 1974 850 Commando. Bike ran well last Fall when put away for season. Bike started OK this year and idles well. However, when revved to about 2500-3000 rpm, the bike starts to loudly backfire from the right (timing side) exhaust. Flame actually shoots out the right muffler end at times! First time anything like this has ever happened. Ease off the throttle and idle returns to normal. Rev up again and backfire starts up again. Cleaned the air pilot (no noticeable blockage), drained the carbs (no debris), pulled the plugs (left plug a little sooty, but right plug was soaking wet). I intend to check the points this AM to see if there is anything obvious going on there as a first step and then remove the carbs (Amal Premiers) for examination. Hopefully, the right carb has an issue. If nothing is obvious, then I can reinstall the old OEM carbs that were on the bike before the switch to Premiers. They are not in great shape which is why I upgraded to Premiers but they might give an indication of what is going on. The situation is a little perplexing as I did not do any significant work on the bike this off-season other than replace the severely degraded rubber bullet junction box under the tank and replace the headlight ear rubber o-rings to stop an annoying vibration. I am certainly open to any suggestions regarding further troubleshooting. Thanks in advance.