..::Taken from my write up at ZX-10R.net::..

So you are riding your 4th Gen and feel a cylinder drop out while riding and your inline 4 now feels and sounds like you're riding a twin. This is happening irregardles of what you were doing and how long you have been riding. The problem seems to come and go, uncommanded.

What's wrong?
-There is an issue in the firmware versions that is causing one of the cylinders to drop off and basically stop functioning.

How do I fix this issue?
-The only two verified firmwares to stop the issue; upgrade your Dynojet firmware to either the 1.6.10 or 1.9.2 versions. If you have a Secondary Fuel Module (SFM) this will need to be updated as well.

Where can you get the firmware versions?
-You can get the latest official release from Dynojet

These versions are hosted separately. Testing results are in bold.
1.6.10 -->Confirmed to work
1.9.0 --> Issue still potentially exists with this version, use 1.9.2 instead!
1.9.2 --> Confirmed to work
1.10.4 --> Untested as of 27JUL13
--> Untestested as of 14JAN14