Sonic’s Workshop: 1990 Kawasaki ZX-7 Saga – Part 1

Sometimes a project takes considerable more time than you first planned on.



Case in point – my 1990 Kawasaki ZX-7. This is a bike I purchased about four years ago, and I am only now getting close to completing it. I could make up all the usual excuses, which are all true but it just seems that time has run away with me. For those of you who cannot transverse the great span of time since I first began this project, I’ll give a little history lesson.

The ZX-7 of which I speak, was a bank repo that I happened on thanks to the sharp eyes of a friend who had spotted it in a towing company storage yard outside of London, Ontario. I arranged to meet with those involved with selling the bike and try to work out a price that would make all those participating happy. Yeah right! It never works out that everyone ends up happy. Just so long as I end up happy, that’s all that matters.

The bike had definitely seen better days but it was fairly complete. However the long days out in the storage yard had not been kind to the Ninja. Vandals had broken in at some point and stolen the speedometer, snapping the bracket and cutting the wiring harness to boot. The tires were very bald and some amateur butchered the rear fender in an attempt to create more of a racier looking rear end. The after market exhaust was old and well ventilated, and held to the rear foot peg by a J-Cloth! – no kidding, the blue and white dish cloth thing.

I know it sounds rough but it did have fair plastics and paint. Combine that with the fact I was looking for an 89-90 ZX-750 in my price range and this bike was looking pretty good.

As always negotiations had to start somewhere and as always the bank rep was aiming high, mint condition high. “$5400?” I said, “That would be the price of a ZX in mint condition. You can’t say this reflects mint condition, can you?” I mean they couldn’t even get it started!



To make a long story short, money talks, BS walks. The bank people didn’t want a then 5-year-old sport bike with untold mileage and dishevelled appearance sitting in their portfolio. So they quickly decided as (I was walking to my truck) that it would be better to take somewhat of a loss than a total loss. $3300.00. I win, sort of.

To further bring you up to speed, once I got the ZX-7 home I did the usual pre spend lots o’ cash inspection in order to eliminate any very expensive headaches half way through the project. Too bad I missed the transmission having no second gear and a very sloppy third. By the time I found that little gem I already had installed new tires, battery, a new Yosh header. Redid the forks and seals, adjusted shims on the valves, (which incidentally requires the camshafts be removed in order to access the shims), not to mention the various plastic trinkets to repair the damage inflicted on the tail by the previous owner. Crap!

The ZX stripped down in preparation for engine removal.

With this sort of problem there is no easy fix. There aren’t any products like LIQUID GEAR REBUILDER that you can simply pour into the affected area and ‘presto’ new gears. Oh no, not that easy, this motor will have to be removed from the frame, stripped and the defective parts replaced. Fortunately, if there is such a word in a case like this, the transmission can be accessed through a bottom end strip alone. Some engines require the unfortunate person attempting a similar repair to disassemble the whole engine from the top down (vertically split cases). Not to mention any names … Virago. Did I type that or just think it? Oh well.

In many cases when working on a bike it’s not the job itself that’s particularly hard, it’s getting to it that is the real task. On the ZX-7 getting to the gears as well as replacing them is going to be a bastard. Simply getting to the engine requires all the plastics and tank to be removed first. After all the pretty stuff has been carefully removed and tucked away, all the engine extras like the exhaust and carb stuff have to be removed.

There’s not much left when the front end and engine are removed.

With the practical and unessential now removed, the engine can be unbolted and lowered out of the frame. Even with all the coolant and oil removed from the motor, it’s still a big hunk of metal. As always, the use of Jack and Tim were the call of the day. Jack, is a hydraulic floor lift, whereas Tim is my friend. No point in trying to be cool and do it all myself, then end up dropping the engine on my toes and damaging the engine further than it already is. Remember, your body will heal … but cracked cases cost big buck$! (Idiot warning – that’s a joke by the way – Editor ‘arris)

With the engine now out and huffed to the operating table for the internal exploratory, the heartless skeletal remains were wheeled outside. As I said earlier, getting into the transmission on this engine is relatively easy compared to taking the engine out of the bike. It was only about an hour and a bit later before I had the transmission in my hands.

“Bloody Gears!” It’s theatrical blood by the way …

It wasn’t great, but it could always be worse. Second gear and its mating gear had obvious damaged dogs, rounded right off. Third gear was also well on its way to mimicking second. You must keep in mind that if there is one problem there usually are two, plus a contributing factor, (the original thing that caused the trouble in the first place). In the case of this transmission killer, my prime suspect (besides the previous owner that probably couldn’t shift for jack), turned out to be the shift drum. Under close examination a large chip was found in one of the slots on the drum.

Having a chunk out of the shift drum at the point where the shifter fork is to be moved into its fully engaged position will also prevent the gears from connecting properly. If the gear does not connect completely with its mating gear, two things will happen. At first the connecting points (known as DOGS) will start to wear. As they wear, the wedge shaped corners (which hold the gears tightly together as power is applied through them) start to become rounded off.

Shifter forks fit in grooves in gears. Gears are held together by ‘dogs’ (projections) on their sides.

Once those dogs have lost their wedge contour, the gears will slip out and away from each other as soon as power is applied. Once a gear starts to slip out of engagement it should be looked as soon as possible – unless you are the previous owner of this particular ZX-7, then you just keep kicking at the shifter lever until the shifter fork bends. Now with a bent shift fork, combined with a badly chipped shift drum, that slipping gear won’t even get close to its mating gear, and as an added bonus, the gear which is trying to be engaged is now shaving large amounts of metal off the bent shift fork.

Thank goodness for oil filters!


Don’t forget to tune in next week for the conclusion of Sonic’s ZX7 saga. Whoo .. whoo .. wh

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