World Superbike Racer
Join Date: Mar 2013
Location: Woodbury, MN
Thanked 565 Times in 446 Posts
Feedback Score: 1 reviews
Ok, then, we'll start with some basic troubleshooting you should start with since it appears you've done very little so far. You've also given us very little information about the bike, maybe some more info like miles on it, anything else you've done in the past weeks, still on the same tank of gas since this started, has the bike been sitting, etc., anything that could help might get more interest.
- remove the PC and see if the issue goes away. Not uncommon for those to go bad and either lose their map, settings, calibration or simply fail. If you have a full Yosh and not a slip on only the bike will run somewhat poorly but should idle fine without the PC.
- are you up to date with maint? Poor idling can, in extreme cases, be a symptom of out of spec valves. They have to be way out to affect idling but it can happen. How about plugs, those newer or due for a change?
- does it run to redline fine? No troubles at a steady throttle or engine speed? No misfiring?
- when was the last time the air filter was changed or cleaned? Might be a trashed filter or an air box obstruction.
- is the tank clean and the gas good? Have you run a tank it so through since the problem started? If not siphon the old stuff out and put fresh in with some Seafoam to see if that helps. Fuel filter clean or new?
Personally I'm leaning towards a bad fuel pump but that's only a guess based on symptoms, the age of the bike and the fact they seem to be failing a lot around here.
Hope this starts you on the fix; if you don't have one yet, get a service manual and follow it for this issue as well. Very handy tool to have.