86 VFR700F apparent timing problem

Riding a few weeks ago I took my bike to just shy of redline before shifting to 2nd. The bike suddenly lost nearly all power. I figured I might have toasted a spark plug, so I replaced them all. That seemed to fix the problem, as the bike immediately ran correctly again. Then it happened again, and it hasn't gone back to normal. The symptoms to me sound like the timing isn't advancing. Around 3500rpm it will start to bog, and if I try pushing it harder it will spit out the exhaust. The bike idles fine, and I regularly use fuel system cleaner so my carbs should be clean. I checked to make sure all of the coils are sparking, and they are.

I have a very open muffler, so any difference in how it runs is quite audible. When it was running fine, around 4,000rpm it would have a very mean sound to it, and I am assuming that is right around the point where the timing started to advance. Now, that's about where it falls on its face.

Any idea what could be causing this? What causes the timing to advance in these bikes?

 

Timing advance is determined by CDI computer, and i don't recall any posts here concerning a failed advance circuit.

 

Reading posts here about failed/failing CDI boxes makes me think that's what the issue is. What I was interpreting as lack of timing (loss of power, and spitting exhaust) is probably just the CDI box not firing two of the cylinders above a certain RPM.

 

Your pulse generators could be going bad, usually with the CDI it is all or nothing, it either works or it doesn't.

 

I am wondering if it is simply some bad or loose wiring on my bike, then. Around the same time, my headlight would randomly turn off, then come back on.

 

Could be a a bad killswitch, you'll want to check that too.

 

It still runs. It idles perfectly most of the time, it just drops out around 3500rpm.

Are the pulse generators in the engine where they can get oil on them? My neutral light has also been flickering lately, and I'm wondering if the oil I have been using is causing it.