Kawasaki Sportsbike Riders Club - Australia - Online Forum

Hi guys, i posted this fault on the general discussion page, but not a lot of feed back there.
My 2003 zx12r has a small but annoying flat spot from idle to just above idle. When i give it a quick little blip/squirt, it will give one, maybe two little coffs before it revs on nice and smooth right upto red line. Only does it from idle revs, to about 1100 rpm. I can ease the throttle on, and no problem, but if i give it a quick little blip as you woul do just before take off, it will give a little coff or two before launching...... Any one got any ideas???

how many kms have you chalked up?
Carby or valves?

Possum wrote:how many kms have you chalked up?
Carby or valves?

its EFI...not carb

first thing I would be doing is getting the EFI checked out (after the usual checks of throttle cables, spark plugs etc)

^^ +100

my best guess is that the plugs need replacing.

If you have changed the exhaust / filters etc, you need a PC3 to tune out the flat-spot just off idle and even then you may not be able to tune it out completely. Dropping 1 tooth on the front sprocket gets the revs up a bit when you take off and this could also help. i have done all these mods plus a few more to my 12 - its a 2005 model. Even after these mods there is still a tiny annoying hesitation if you just roll the throttle on from a standing start.

yeah, all the usual stuff i suppose.... It's only done 11500k, it's all stock original as, and yes smitty, it is efi, so wont be looking at carbs or plugs for a few more k yet, usually good for about 20k, definately not looking at valve clearance yet, i think i'll go with the basics first, check and give the throttle body a good clean, the filter element the same, a bit of a tune up so to speak and see how that goes before we start getting into anything too serious.... thanks for your feedback guys, pretty much just confirmed what i was thinking..... will keep you posted on the diagnosis and progress as i go.....