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DirtyGirl's Kawasaki ZXR 250
Conversion from street bike to race bike

Preparing a street bike for vintage racing can be a relatively simple process, but building a reliable vintage race bike is more involved. I was fortunate with my first vintage race bike, which was minimally prepared when I purchased it, yet it was very reliable. I've seen many racers with similarly prepared bikes spend their weekend making trackside repairs instead of racing, and I found the few trackside repairs my bike required to be excessively stressful; so with these lesson in mind, I wanted to prepare a racebike that would be as reliable as possible for a period legal vintage racer.

The conversion from street bike to race bike will be continuing through March and April 2009 - stay tuned for more photos and updates!

The Teardown - February 2009

The ZXR came into my posession in mostly stock street condition, with a few parts in boxes. A twenty year old bike with about 36,000 km's and very likely several years of storage, before it was shipped from Japan and stored for a few more years, it will likely have accumulated several types of damage. The only way to be reasonably confident that this bike will be reliable is to take it all apart, inspect everything and replace, repair, fabricate or remove all worn out, age damaged, storage damaged or shipping damaged parts.

My ZXR 250 before the teardown process got properly started This is my 1989 Kawasaki ZXR 250 in street trim, in the condition in which I acquired it. The exhaust system and some brake parts are in a box that came with the bike. While there are some signs of previous-owner-repairs (the re-painted tank and frame) under the bodywork the bike seems to be in stock condition, which I take as a good sign. Never brought into the Canadian market, this bike most resembles an early 90's ZX7 to the eye of a Canadian motorcyclist.

The first step is to remove the bodywork from the bike, and apart from a few non-stock fasteners, this was easily accomplished. I should say at this point that I'm not a mechanic, I'm a mechanically inclined amateur and I have some experience with the basics of maintenance on a motorcycle. I would be very reluctant to undertake this project without the assistance of a mechanic and machinist (Timothy of the Speid Motor Co.), but the disassembly part I feel comfortable with. I expect to be more familiar with the bike after I've taken it apart, and the disassembly process can be safely entrusted to an amateur.

just starting the teardown process on the Kawasaki ZXR 250 to prepare it for vintage racing
ZXR 250 with bodywork off After the body work, tail-lights, foot pegs and controls, passenger footpeg brackets and other attachments are off the frame, I started detaching what electrical connections were then exposed. As the frame of the bike is more exposed, the level of quality in the construction becomes apparent, the welds on the frame - even inside - are beautiful.

The remaining fluids (oil and coolant) were drained next.

With the airbox off I get my first good clear view of the carburetors. One of them seems stuck, but three of them slide with good vacuum sounds, and two slide easily. The carbs will need to be thoroughly cleaned, but it's possible they will need no more than that.

The sub-frame comes off easily, giving me a good clear view of the very trick and modern (for a vintage bike) looking single shock rear suspension. The shock may be very hard to replace, so I'm hoping it is in useable condition.

ZXR 250 with the airbox removed
ZXR 250 front end view with lights and guages off With the lights and gauges off (the two separate assemblies removed easily; each a unit to itself) the ZXR 250 starts to look a bit more like it's becoming a race-bike.

The handlebars are beautiful solid aluminum pieces, but both are bent, so new bars are added to the parts list. The upper triple clamp is a beautiful casting and it's in excellent condition.

The radiator and cooling system come off the bike next. Old and brittle hoses are very tiresome to deal with, and there seem to be a lot of them. The large and curved radiator is another one of the very modern looking styling cues of this bike that make it look so unlikely for vintage racing.

Apart from the difficult hoses, the cooling system removal is pretty straight forward.

ZXR 250 with the bars off and nearly stripped to the frame
ZXR 250 Kawasaki Japanese labeling on the inner bodywork This sticker is on the outside of the interior bodywork, under the tailpiece and seats. On my Canadian market Japanese streetbikes these labels are in English and hold no charm for me, but these incomprehensible Japanese stickers seem much more fascinating somehow.

This image shows the beautiful TIG welds on the aluminum frame, as well as another Japanese identification sticker. In some ways this bike is a welders dream bike, with beautiful examples of both MIG and TIG welding on the frame. I believe they are hand (not robot) welded, but the skill of the hands that made these welds is impressive.

ZXR 250 Kawasaki frame sticker and weld closeup
ZXR 250 Kawasaki carburetors Carburetors are the next to come off the bike. They will need a very through cleaning at the very least, possibly more intensive care.

Air and fuel hoses and assorted electrical components come off first to get them out of the way, then the carbs, with a great deal of effort, come loose from the motor.

This is where I start to really appreciate having help and advice - this is further into a bike than I usually go by myself, and for some parts of the disassembly a longer wrench doesn't help. I don't think I could have pulled those carbs off by myself unless I ran a line to a pulley system on the ceiling and dangled myself from it.

I can identify this label as tire specifications, because I recognize the numbers specifying the size of my front and rear tires.

Tires will be included in my first parts-order for this bike, I've found a number of tire options available, including the models of tires I've used on my Honda.

ZXR 250 Kawasaki tire label
ZXR 250 Kawasaki engine left side view Left side view of the ZXR 250 motor still in the frame. I've got a lot of cleaning here, and I suspect 'new sprockets' may appear on my parts list. Eventually the engine will have to be bead-blasted and painted, but that may be an end of season project, lower on the priority list.

Right side view of the ZXR 250 motor still in the frame. Showing some previous crash damage, or possibly shipping damage.

ZXR 250 Kawasaki engine right side view
ZXR 250 Kawasaki rear suspension A better view of the rear suspension, now that most of the electricals are out of the way.

The single shock rear suspension on my Honda doesn't seem particularly stellar, and I'm hoping this suspension is either more effective or in better condition (or both).

The built in ride height adjustment on this suspension is elegantly simple and practical too.

The best way to make a bike take up a lot of space is to start to take it apart - the first half dozen parts I took off filled one box and expanded into two others. This is what the parts boxes looked like part way through the first day of the teardown.

ZXR 250 Kawasaki teardown - a half a days worth of parts in the boxes
ZXR 250 Kawasaki engine seen from behind ZXR 250 engine seen from behind, with the carbs removed

The carbs were very stubborn to remove, and will probably be just about as difficult to get back on.

This is what the parts box looks like at the end of the first day of the teardown. The box on the left is mostly parts I don't think will be going back on the bike - street gear like taillights and headlamps, and other non-essential for racing parts. Everything else needs to be thoroughly cleaned and inspected and if found to be suitable will go back on the bike.

ZXR 250 Kawasaki boxes of parts at the end of the first day of teardown
ZXR 250 Kawasaki with the engine out of the frame

Day 2 of the teardown

On the second day of the teardown the engine was to come out of the frame. I'm bigger than my engine, but probably not by much; I think the engine is about 90% of my body weight. So this is another part where I needed help, although I might have managed it on my own with an engine hoist. With a very long wrench (and a minimum of impolite language) I managed to loosen the nuts on the engine bolts, but pulling/pushing the bolts out was a two person job, and needless to say I didn't carry the motor to the bench.

ZXR 250 engine on the bench, waiting for it's own teardown. Until we know what seals and gaskets can be had for this bike, it's hard to decide how far into the motor to go - I'm reluctant to open anything I don't have a gasket for.

ZXR-250 Kawasaki engine on the bench
ZXR 250 Kawasaki frame The frame stripped of all it's parts and brackets. To me it seems amazingly light weight, and even the MIG welds on the inside of the frame are very nicely done welds.

The forks still have to come apart to be inspected, hopefully new seals and oil will be their only requirement, but that has yet to be determined.

ZXR 250 Kawasaki front end disassembled
ZXR 250 Kawasaki reduced to a pile of parts after the second day of teardown That's the entire bike in a pile, except front end and frame, which are still on the bench. It's amazing how big a bike gets when you start laying out the parts. I wonder how far they'd stretch if you laid all the parts of a bike end to end?

What a girly toolbox with two kinds of hand cleaner and two kinds of gloves!

My racing toolbox proved to have just about everything I needed for the teardown job. There were a few specialty tools and extra large sizes of sockets that I had to borrow, but for the most part my toolbox seems prepared to cope with this bike. I might manage to justify the purchase of a few larger sockets... I do love shopping for tools. On the other hand, there's a limit to how many more tools I can add before I can no longer lift my toolbox.

The DirtyGirl's toolbox sufficient for the teardown except for one or two tools
blood sacrificed to the racing gods They say racing is fueled by blood sweat and tears, but I had not intended to contribute any bodily fluids to this project. It's too cold in February for me to work up a sweat while taking apart my bike. Occasionally wrenching on my bike drives me to the fits of frustration that induce tears, but not recently. I do own mechanics gloves, more than one pair and in fact I had a pair in my pocket at the very moment I scraped my hand on a hose clamp. (That'll teach me, right?) So I managed to bleed on my bike already.

Maybe that's a good sign. I think I lost about that same amount of skin the last time I crashed at a track day, so perhaps I can convince myself I've already contributed the required amount of skin to appease the racing gods.

After the teardown - April 2009

Preparing for the rebuild - the in-between steps

After the ZXR 250 was entirely taken apart, each piece had to be thoroughly cleaned and inspected and assessed. All bearings and seals were replaced, which was an expected necessity. The chrome on one fork was found to be badly corroded, and I began looking into alternatives - replacement seemed like a good idea, except sourcing and buying from Japan would be too time consuming, and places that make fork tubes for cruisers don't deal in such thin-walled tubes.

1989 Kawasaki ZXR250 forks and frame parts - one fork tube at the chromers Eventually a source for hard chrome resurfacing (North American Hard Chrome; a company that generally services the chrome on hydraulic cylinders) was found that could repair my corrosion damaged fork tube. They did a beautiful job, and both my fork tubes are in perfect condition now, and all the internal parts are thoroughly cleaned. I've got all new fork seals and dust covers, new wheel bearings and steering head bearings, and the re assembly of the front end can begin.

Every one of the bits and pieces associated with the frame were cleaned and checked for signs of damage. Except for some surface discolouration, all the bits and pieces associated with the frame, from the axles to the mounting brackets, are in good condition. A wash tank with mineral spirits, a sonic cleaning tank and a blast cabinet were all used in the process of cleaning various parts - this isn't a cleaning job for the faint of heart.

1989 Kawasaki ZXR 250 frame parts all cleaned
1989 Kawasaki ZXR 250 brake calipers before and after cleaning The before and after pictures of these brake calipers show what a good job a sonic cleaning tank can do - filled with nothing but distilled water, sometimes a drop of dish soap and/or baking soda, this is easily one of the most environmentally friendly parts cleaning tools a shop can use. It did a fine job cleaning these old brake calipers, even after cleaning with brake cleaner the one on the left is still caked in brake dust, brake fluid and who knows what else. The one on the right spent 30 minutes in the sonic tank and came out looking nearly new.

The air filter on the ZXR 250 disintegrated in the disassembly process, and although I did manage to get a Kawasaki part number for this filter, it's not one that is used on any bike imported into the USA or Canada, so I can't order it here. Ordering through a Japanese dealership might be possible, but the timeline (not to mention the expense) is prohibitive.

The 'Plan B' is to build an air filter. The cage for the ZRX's air filter is in relatively good condition, I only need to fashion a foam 'top-hat' shape to fit over the cage and inside the intake of the airbox. I've acquired lots of filter material to play with, and this sub-project should be less time consuming than finding a source for hard chrome resurfacing.

1989 Kawasaki ZXR250 Air filter - too old to use
The next step in the project is to reassemble the rolling chassis. New tires are mounted on the rims, with new wheel bearings all around. Brake pads are sourced and ordered (turns out the ZXR uses the same brake pads as found on the rear of the 250 Ninja, so are easy to order in Canada), and a new drive chain and front sprocket (rear sprocket seems to be in good condition) are also on the list of new parts for the ZXR.

My initial estimates to get this bike race-ready are going to be reasonably accurate. If you buy a street bike to take vintage racing, you can expect to put about the same amount of money you spent on the bike into the process of converting the bike for racing, or even more when you include the normally consumed items like brake pads and tires. At least the parts can be acquired on the installment plan, in bi-monthly trips to the local shop to pick up the next parts needed in the assembly. I suspect if you buy a factory racer for vintage racing, your costs are exponentially higher, for both bike purchase and bike preparation.

The Reassembly

ZXR 250 rolling chassis reassembled April 2009 We have a rolling chassis again! The ZXR's beautiful green rims have new tires mounted, and the frame is all reassembled, from the forks to the tail section sub-frame, and it's all gleaming clean.

Brakes still have to be reassembled, although except for pads and fluid, nothing else is needed. The rear sprocket is in excellent condition, although that wasn't apparent until it was cleaned. The front drive sprocket will be replaced. Assuming the project continues to go smoothly, there aren't many more parts I'll have to buy. I may be able to spurge and replace the beautiful but bent original clip on handlebars.

The air filter was a step that stumped me briefly. I managed to find a Kawasaki part number for the filter, but it's a part that's not available here. While many bikes share filters, there isn't a single Kawasaki sold in Canada that has a filter anything like this; even the ZX-7 with a similar airbox has an completely different filter. There is no possibility of saving the old one, it's disintegrating into dust. So I decided to build one. I bought some sheets (about 20$) of air filter foam, and some contact cement. I've built puppets out of foam sheet, but this was a bit different. I took the best measurements I could of the disintegrating old filter, then made a paper pattern. Using the pattern and the plastic frame/cage over which the foam element fits, I revised my pattern, then started cutting foam.

Fortunately I'd left my foam a little bit long, knowing it is easily trimmed to fit, and eventually I got a lovely snug fit over the plastic frame that holds the air filter within the airbox.

a homemade ZXR 250 air filter constructed from foam sheet
foam sheet air filter for ZXR250 Kawasaki, unavailable in Canada By using contact cement with a dry mount technique (brushing the contact cement generously over both surfaces to be bonded, then allowing the glue to dry completely - then carefully aligning the two surfaces before firmly pressing them together) you get a very strong bond, like a weld, stronger than the surrounding material.

building a ZXR 250 air filter from foam sheet
So the air filter is checked off my 'to-do' list, and I'm one (tiny) step closer to having a finished race-bike. The next (scary) step is taking apart, cleaning and rebuilding the carburetors... that's one of those parts I'm very glad to have access to professional help!

June 2009 Update

New carburetor parts, specifically o-rings, were difficult to source. By looking through a stack of Kawasaki parts books, old fiches, I found some very similar looking Canadian market carbs, and found o-ring part nubmers that way. Armed with a part number, Burlington Cycle was able to get my o-rings quite promptly. Leaving many dollars lighter with barely a handful of parts... I weighted my precious new o-rings later to discover that my parts cost was nearly 3$ per gram, nearly 100x the cost of silver! Precious, precious o-rings.

The carbs were still being cleaned and need to be reassembled, exhaust and other parts were still coming together. Stay tuned!

October 2009 Update

The carburetors are finally cleaned and reassembed! My precious, previous o-rings are now installed, and the magical little parts that make up a carburetor are now slightly less mysterious to me than they were before. Photos and more about the carburetors: ZXR250 Carburetor Page

The Kawasaki ZXR 250 racing preparation rebuild story will continue... stay tuned to see the complete bike!

The ZXR 250 Kawasaki project is underway thanks to Timothy Speid of the Speid Motor Co. for all his endless expertise and patient help with the teardown and rebuild process.

In the beginning... January 2009

Basically the plan for the preparing the ZXR 250 for vintage racing in 2009 is to take it all apart, clean everything, replace all bearings (and anything else too old or damaged to go back on) then put it all back together again, drilled and safety wired.

I'm quite certain it won't be nearly as easy as that sounds, but it's a comfortingly simple plan ;-)

Kawasaki brochure photo - ZXR250 left side view
The original Japanese brochure introducing the Kawasaki ZXR250 in 1989 contains this photo - the ZXR250 seen from the left hand side.

Kawasaki brochure photo ZXR250 right side view
Kawasaki ZXR sales brochure photo - the ZXR250 seen from the right hand side

Kawasaki ZXR250 Pages:

Original Documentation - OEM Specifications - Race Preparations - Carburetors - ZXR main page

Back to the ZXR 250 Page - Back to the Articles Page

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