How do you change spark plugs on a ZX12 Kawasaki?

Answer 1

Guide to changing the spark plugs for novices (like me)

I just replaced the sparks on my 2001 12R - I'd previously read alot about some people finding it easy and others finding it impossible. I didn't think it was easy, but then again I'm only capable of relatively easy stuff on my 12R (ie oil change, filter clean, pilot jet mot, brake service etc etc).

I thought I'd put together this little guide for novices like me that want to attempt it. In all, it took me about 30 minutes per spark. I didn't mess about - I removed the fairing, ram air covers, tank cover, seats and coolant expansion tank. It can be done without removing some of these, but it will be alot easier if you just get them out of your way. The expansion tank can just be unscrewed and left to dangle on the pipes. Don't bother removing it completely.

First of all, you will need the special angled tool from the 12R's tool kit. The idea behind this tool is that the bigger end goes down the spark plug tube and locks onto the spark plug, whilst the smaller end is for a spanner or socket set to lock onto. It has to bend in the middle to enable you to get it into the spark tube as the clearance above is not enough to get it in otherwise. Look into the bigger end of the tool and you will see a rubber washer that grips onto the spark plug once it has been unscrewed (else you'd never actually get it out of the tube).

Second, obviously get hold of the spark plugs first before attempting the job - I've read conflicting reports about which spark plugs are the correct ones. I still don't know what's right and what's wrong, but I am going to tell you what I found out. First of all, I got hold of the NGK CR9EK sparks as referred to in the manual but was surprised when they looked a little different from the sparks that were already in the bike - the difference was at the top of the spark plug where it latches onto the stick coil and consequently, the stick coil wouldn't fit on properly. Someone else suggested that the CR9EIX were the way to go and I was relieved to find that these had the same upper connection as my existing sparks. You can see the difference between the two at the following internet locations NGK.com - Application Search Results andCR9EKB - NGK PLUGS "C" by chi town choppers , inc .

The CR9EIX sparks work like a charm in my bike, but I suspect they have a smaller lifespan because they are not multiground sparks like the ones that came out (I guess that this lenghtens the life of the gap, but I'm not really sure). In summary, I can tell you that the CR9EIX work great in my bike and fit inside the Denso stick coils very securely - but I can't tell you how long they will continue to work for so you might want to check it out a bit more yourself.

As some people have said, removing the plastic and rubber covers will make your life easier to get the job done, but I'd recommend you leave them there because they are effectively stopping dirt, moisture and other sh*t getting down the side of the stick coil where it will end up in the top of your engine the minute you take the spark plug out. I noticed moisture on the side of one of my stick coils and (more concerningly) some oil on another (that's a differnent story).

OK, so on with the procedure. Looking in at the top of the engine you will see the top of the stick coils coming out of the top. These stick coils have 'Denso" written on the top of them. Before doing anything else, you'll have to pull the 2-wire connector off of the side. It has a little plastic locking tooth on it so you have to press down on the tooth whilst pushing the connector towards the back of the bike. Mine were relatively easy to get off, but I found a small flat blade screw driver made things easier - it was possible to use the screwdriver to press down on the release catch at the same time as pushing it backwards and off.

After this you need to get the coil sticks out - the is the single hardest thing to do in this job (at least it was with my bike). Some people have reported that their coil sticks came off easy, well I can tell you that mine were stuck on like a bitch. I'm a little suspicious that some of the folks that can get their stick coils off easy are using the sparks with the different interface type (as described above) which means that the denso stick coils just sit on top of it, rather than gripping on to it. I imagine this will work fine as these high voltages don't need a perfect electrical connection to work - but, I just prefer a solid mechanical connection as the basis of a good, reliable electrical connection.

The key to getting the stick coils off is to use a large flat blade screw driver and put it under the connector seat (towards the back of the bike) that sticks out of the side of the coil and then twist the flat-blade to pop the coil off. When you pop off the first coil you instantly realise from the force required that there was no way you were ever going to do it by hand like other people have said they do (like I say, this might be down to the different types of spark plug top). One thing that I noticed is that the plastic cover for the rubber mat has a neat-feature - a little channel under it that allows you to get a flat-blade screwdriver to the middle sparks by putting the screw driver under the piece of the plastic cover that sits in-between the middle and outer sparks (on both sides). After that, you can wrestle out the stick coil. If you do the ones at the outside first you will see how long the stick coil actually is (about 12 cm by memory). The last 4 to 5 CM is rubber and can bend, which is a godsend when you do the ones in the middle (if it was 12cm of plastic, it simply wouldn't be able to come out).

OK, the most difficult bit is done. Using the angled tool, you put it into the spark tube and push it as far down as you can by hand. Start turning it anti-clockwise by hand until it locks in position - thus the tool is located. You can then use a wrench or socket set to loosen the first part of the spark off (it shouldn't take much force if the person who installed the sparks used the correct torque). You should then be able to unscrew the rest of it by hand (depending on the size of your hands!). After many, many turns you'll eventually notice it suddenly becomes easier because the spark has come out of the threads. You then pull the tool out and hey presto, there's the spark being held by the tool's rubber washer.

Replacement is just the reverse, but it's a good idea to add a little grease to the spark threads before putting them in and spray the stick coil outers with a silicone grease or WD40 before putting them back in the spark tube. The two outer sparks are obviously easier than the inner ones - but you have to wrestle with everything throughout the entire job because it is just so tight. This is why it takes so long.

I'm no idiot, but I also am not capable of doing complex stuff on a bike. For my level of expertise, this was a reasonably difficult job the first time around. Like everything though, having done it once I think I would find it quite easy the next time I do it.

Hope this helps someone,