12R Refresh Project

I've been a member of this forum for quite a while, and have read numerous great threads where people have done rebuilds or clean up projects.
Now its my turn!
These days I'm flat out with work, have a 3yo daughter to chase around and another baby due in about a month - I'm very time poor...
So I decided - I need a new project! 😆



Over the years I've accumulated a heap of spare ZX12 parts, just because they're becoming rarer and prices for good parts is just going up.
Last week I spotted a 2004 B3 advertised on Marketplace - not running and no registration, a bit rough around the edges with a "fried ECU". Well good for me, I happened to have a spare ECU and key/lock set in the shed. The AUS/EUR 2004-2006 ZX12's have a built in immobilizer, so you cant just swap the ECU out and have it running. You need a matching key for it to start up.

I met up with the seller, it seemed as if someone had lost the keys in the past and an attempt to hotwire the bike was made.
First I installed the battery/tray from my 06 bike.
So I plugged in my spare ignition switch and ECU, cluster turned on, but there was still a fault light flashing at me.
I worked out quickly that the original ECU wasnt fried (it was in a box) but what was fried was the immobilizer antenna unit that sends the key information back to the ECU. This had been removed and opened - I'm guessing as part of the hotwire job.

I pulled the immobilizer antenna unit off my 06 bike and then the immobilizer fault codes stopped and the fuel pump primed. I wasn't too keen to fire it up yet as the fuel was pretty stale, and I was unsure what the tank condition was actually like.
Looking over the bike, I thought even if the motor was no good, I could probably make my money back by parting it out.
Its got a full Yoshimura exhaust system, Power Commander, carbon fenders, good Radial forks - etc etc etc
Title checked out ok, so after a bit of bargaining the bike was now mine.
I checked the oil and coolant, disconnected the Power commander, installed the fuel tank from my 06 bike and fired it up.
Seemed to be nice and smooth, no strange noises from the motor. A win I think!






Got it warm and dropped the oil. Also noticed the cam cover gasket is leaking a bit and making a mess, possibly the cam position sensor o-ring.
It had a 0004 oil filter - I haven't bought one of these since 2010, so that tells me the oil probably hasn't been changed for a very very long time.


I had a look in the Oil for glitter, or any indications of metal - nothing visible to my eyes. I'll probably cut the filter open later for a look.
Fitted a new 0008 filter, sump bolt gasket and some fresh Aussie Penrite 10w-40 Synthetic Oil


While I was doing this I decided to remove a bunch of little LED "show lights" that were on the bike. The fuse box was missing a couple fuses so I replaced them too. Tail light fuse was blown - strange...
I also pulled the Genuine air filters out, and checked the condition of the air box. Pretty clean. Replaced the filters with some cleaner low use OEM filters that originally came off my brother's old ZX12. Only other option I have here are BMC Race, but dont think this needs them yet!

Went to fire the bike up with the new oil. No go!
What? I hadn't done anything besides remove the LED's. I checked a few things, and nothing was out of the ordinary.
Fault code was showing Cam Timing sensor. Pulled the sensor out of my 06 and swapped them. Still no go.
Checked the wiring diagram in the Workshop Manual. Pin 12 on the ECU.
This is what I found -

Obviously part of the hotwire job. Tried to inject power from the tail light to the ECU - this explains why the Tail light fuse was blown.
Reinstalling the fuse was sending a dodgy voltage signal to the ECU. I cut the wire and the bike started again!

Put the original Cam pos sensor back in with a new O-ring.

Got it warm and just checked the TPS voltages.
This handy adapter from NinjaYorkie makes an easy job of it!





Not much else done. I've got to come up with a bit of a plan for it.
Fuel tank and fuel pump is probably the highest priority to get checked out.
But I'm thinking for now, change the leaking cam cover gasket - while I'm at it check valve clearances and change spark plugs and the figure 8 gaskets.
Radiator and coolant flush while I'm at it.
Needs a new battery and tyres and I've got a few little parts to chase up.
Then probably fork oil, brake fluid, and check all bearings.
Besides the Chinese fairings, its in pretty good condition. The carbon front fender and rear hugger are pretty nice.
I do have a complete full set of genuine 04 Candy Thunder Blue fairing's I can put on this bike.
It will make a nice clean street bike. My brother is already talking about buying it off me - he sold his 2006 ZX12 a couple of years ago when he moved overseas for work, but due to Covid he returned home and is missing his old bike. I'll have a think about that...

Stay Tuned!