I had similar symptoms on my previous ZZR, was a knackered ignition coil. Thing is there is no easy way to test the coil so you 1st need to check plugs and the HT leads if they are ok swap out the coils. For a coil you are looking at about £20 for a pattern part or similar for a used OEM the bike has 2 of them (I've got one on the shelf you can have but it came with a mixed box of old parts so I have no idea if it's good).Originally Posted by Trev_P
Fuel starvation, usual check the breather is clear, check the fuel line is not kinked/split/etc. If the carbs have been fiddled with I'd check they are sat right and the ram air is plumbed properly, as the tank and airbox would have been off, they are fiddly to get back on properly and a lazy spanner monkey may have just wedged it all together badly. I'd check this stuff before the ignition system because it's easier, as you'd have the tank off to do this you can check the ignition stuff after.
Fuel pump relay and pump can also be checked. Relay is easy it's a little box behind the LHS tail piece and you just need to see if the resistance is in spec (multimeter job). Fuel pump is a bit more of a task and unless you have a pressure gauge to attach to it you can't get an accurate test. If you do, you put the pressure guage inline to the outlet. Connect the pump directly to the battery and when fuel starts pissing out block the outlet hose, the pump will then eventually stop and the reading on the gauge is what you want to compare to the spec. If you don't have a gauge then all you can really do is disconnect it at the carb end and with the bike on the centre stand and in first gear (don't pull the clutch we don't want to spin the starter) hold the starter down. As the line is not connected so not pressurised if the pump is alive you'll be shooting fuel through the line (so aim it in a receptacle). This is easy to do when the tank is lifted to do all the other stuff but it'll only tell you if the pump is working or not, you won't know if it's working but out of spec.
The above sounds daunting but in reality you can get most of it done in half a day. If you do fancy doing any of that yourself shoot me a message with an email address and I'll send you the kwak workshop manual, it has all the specifications for testing and also gives far better, clearer and more accurate instruction than the Haynes for this bike.
