Could use some input regarding a running issue...
I wonder if any of you experts might comment on this issue that just popped up on my 1996 VN750 (8.5K miles) I've been driving it fairly regularly for a year now with no issues; bought it from an older gentlemen who didn't rid it much.
On the way home from work Friday evening I noticed the engine running rough (actually sounded like a cylinder missing) as I was heading down a short stretch of road to my house. Its downhill and requires little to no throttle. As I pulled in the driveway and stopped at the garage the engine was idling low and rough and stalled. I shut it down and finally got a chance to check it out this morning.
It cranked up Okay but I noticed the same rough running at idle but seemingly smooth and normal at RPM above about 2K. I pulled each plug wire off in turn to try and isolate the cylinder. I could hear that all four plugs were firing but noticed little or no change roughness when I pulled the rear plugs, so it appears the rear cylinder is at issue.
I then pulled the seat off and checked battery voltage just to eliminate that: 12.2 V ignition off, 14.3 or so volts when I rev to 4K so that appears to be fine. Then pulled the tank checked fuel flow while sucking on a piece of tubing connected to the vacuum fuel valve - fuel flow was excellent from both sides.
At this point I'm thinking some bad fuel or some dirt in the rear carb that has messed up the idle jet. I am planning on pulling the carbs and and cleaning them up then installing all new fuel and vacuum lines to the carbs. Any Ideas or suggestions?
Thanks in advance for any input,
1996 Vulcan 750
1980 XJ650 Maxim