Thanks! Yeah the tuners were saying they like them around 4.x, which is were it is at the top of the RPM range. I know it's common for bikes to be lean at low RPMs for emissions, and I know ours aren't the most efficient bikes (compared for example to Honda or BMW parallel twins), so I wasn't sure if the running to rich might be normal.
My fuel economy was down. I had tried many things and I took it to the tuner, and they tried more.
Before taking it there I had installed rebuilt, flow matched injectors, and it didn't help. The tuner told me because idle was fine it wasn't a sensor, and that it was either injectors or ECU. The ECU seemed possible
but unlikely--more likely for an ECU issue to cause a more serious problem. But I tried: I swapped in a different ECU and it also made no difference.
I have another pair of injectors with slightly lower flow which I may try, since it's rich, but I don't think that's the real problem and I'm reluctant to spend the time there.
I didn't balance the TBs after the injector swap. I expect that would help a little, but don't think it's the real issue.
Valve clearance, plugs, air filter and fuel pump are good.
Any suggestions for what to look at next?
Could a stretched timing chain do this?
I think a clogged cat could. The symptoms seem different from when it's happened to my car. For one thing I don't notice a booming sound under power. Any suggestions for how to check? Can I see into the cat if I remove the muffler? I could just swap in a cheap muffler and run it for a tank. But I'm hoping there's an easier way to tell.