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Discussion Starter · #1 ·
A couple of weird issues that started up out of nowhere and haven't gone away.

First the backstory:
  • Recently bought 2012 ZX-6R
  • ~22,000 miles
  • No real mods disclaimed to me at purchase other than short straight-pipe exhaust and a couple basic lighting changes. Everything else appears stock.

Other than the issues I'm about to describe it runs and feels fine.

Okay, so on to the issues..

  1. A couple weeks ago it started what I can only describe as a warble. It changes tempo with the RPM.<link removed> Here's a link to an audio clip I tried to filter out. It's a pretty rough clip but if you listen to just the engine you can hear it. At idle there is no sound and it only seems to present itself after 25-30mph so I can't get very good audio. But it sounds like a wahwahwahwahwah vs. just a clean waaaaahhhh... :nerd: One thing to note, it only does it when on the throttle and typically holding the throttle. At idle, closed throttle the engine sounds fine.
  2. Lately it has been "popping" a lot more on deceleration/braking/down shifting. Like, if I'm cruising along at 75mph and let off the throttle, the exhaust will pop 2-3 times, downshift, pop 3-4 more times...
  3. Around the same time as issue number 1, I started noticing that at very low speeds (0-10mph), especially when cold, with just a touch of throttle (imagine driving through a parking lot), it lurches. Not terribly, but I definitely feel like it's lurching as if I'm slightly rolling the throttle on and off (but I'm not).
  4. Finally, and to add to the "no mods disclaimed", I've noticed that the speedometer is ~5mph too fast under 60mph and above it seems to climb to ~10mph too fast. Whatever that may mean. I doubt just the exhaust is causing such a big change.

My assumptions:
  • It has mods in the way of a clutch/sprocket/etc. that I don't know about causing the speed issues. But How do I find out?? It looks stock to me.
  • There's a fuel and/or air issue causing the other problems
  • Issues 1, 2, 3 feel like they're all related to me.

Things I've done so far:
  • Changed all the spark plugs.
  • Changed the oils.
  • Cleaned out the airbox/filter.

Any suggestions?

Update: Today cruising around 5k RPM I was able to notice that, while it's "warbling" the RPM is actually fluctuating just a hair on the tach at the same rate as the warble.
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