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I thought it would be cool to own a classic sports bike so when this 1984 GPz900R appeared on eBay at $500 AUD with a broken starter clutch, it was a cheap way to get a piece of history. I won the auction at $661 so a good project bike was mine.
I obtained it in October 2006 and it now marks 18 months from start to finish. With so many projects and my desire to keep collecting bikes, money has to be allocated carefully. I have tried to document the progress of the work in date order. Its interesting to read my earlier findings and then the revisions as I go.
Aditional finished pictures are here, taken in November 2009, some 18 months after first registration.
Before Shot
This picture was taken in the back yard of the previous owner. He got it from someone for next to nothing and was going to put it on the road but decided it was too much, so he sold it as a non-runner. I shipped it up from Melbourne and decided to strip it and rebuild it to use as a daily runner with the view of restoring it back to original. Its a 1984 zx900A1 and has had a very hard life!
After Shot
April 2008 has seen the bike achieve registration! The work in rebuilding the suspension has paid off as the handling is superb and fitting the freshly painted body work sets the bike apart from all the others.
Post Rebuild Issues
A day after registration, the water pump blew a seal and the water went everywhere. A replacement water pump seal and new radiator cap (1.1bar not the 0.9 version) has fixed the cooling system and at 110klm/hr the needle sits nice and low while around town starting and stopping puts the needle at the top end but the cooling is working fine (Hint: bleed the system at the pump first then the thermostat housing by squeezing the hose).
There is a small weep in the bottom cam cover but I now have a new cover to do at next oil change, I had to put a bush in the gear change level because it was too loose. I just need to tighten up the front end after covering 670klms this weekend playing with my new toy!
Remaining Work to do
The bike has a loud 4-1exhaust and for around $1200 I can get 4 into 2's fabricated locally. the mirrors and the blinker mounting plates require replacement. The reflector inserts for the fairing require installation and the lower fairing inserts that hide parts of the engine need to be installed also. At some time in the future the wheels need to be cleaned back and repainted.
Finally, the engine will need to come out and be repainted but that's 12-24 months away. Next engine service is 400Klm away. So far so good... plans for the 85 GPz900R customisation are in the work!
The Project Plan
At first the goal was to replace the fork seals but a disassembly of the forks has revealed a bit more damage than I expected so here is a list of the work I need to get it registered:
All in all not to bad to get it on the road... lets see what happens. (See the updates below.)
What needs to be done to restore this bike to new
The bike is complete so thats a good point, cosmetically it needs cleaning up and a new paint job with a few plastic repairs on the lower fairing. Some rusted fairing brackets need restoration so in all the following list would be what I will do to it once the z1A, z1000A2 and z900-A4 are finished.
Powdercoat the frame and fairing brackets
Neaten up an earlier repair job on the tank
Repaint all the body work (Some items are in getting done now!).
Replace the exhaust with a replica 4-2
Cleanup the engine
Blast clean the wheel rims and repaint
Vapour blast all alloy pieces (A lot of these parts are done now and more to go!)
Replace all the fasteners
Repolish the tank filler cap
Restore the paint on the lower fork legs
Cleaup the brake plumbing
Restore the radiator assembly
11 November 2006
Did some cleanup work on the dampers and put them in caustic soda to see if they would clean up, also put the bottom of the fork leg and the old TCV just to see what happens to it.
The Damper return spring is still stuck fast inside the lower fork leg. Went to All’s Bike's n Bit's to buy two TCV's for the forks, they were in perfect condition and cost me $55 AUD.
Next step is to drop these legs into the Hardchrome shop when I pick up my z1000A2 fork legs next week some time.
30 November 2006
The internal damper rods, damper springs and lower fork legs have been cleaned. There are still some rust buildup inside the lower legs that I will need to clean up possibly with a honing stone. One leg is perfect the other has pitting inside.
The fork tubes have gone to get hardchromed and the z1000A2 fork tubes have been picked up at the same time.
I have sourced the pads and disks as well as the springs and just need to collect the bush kit from Mid-Town Kawasaki next week. The anti dive units are partially ok, one is working the other slightly jammed up. Still cant separate them from the actuator part but a few suggestions have flowed in from the GPz900 forum.
6 December
Last week the forks went in for hard chroming and I pickup up a few alloy items that needed to be cleaned. I discovered a crack in the front lower fairing mount which I will weld up this weekend if I get time. Forks are due back by mid December.
Just need to source the disks when the finances are better and that should be everything done to get the bike road worthy.
When I finally got the forks apart on the GPz, here is what one of the springs looked like! The main spring is ratshit and the rust in the leg is from it being eaten from water in the fork leg. The damper spring is pretty rusty and the TCV is eaten away! A good set of Travel Control Valves are shown above the spring. Koni still make replacement springs if I want to purchase them. They need a spacer piece installed to get the dimensions correct. Racetech also sell GPz fork parts (so I have been told).
The anti-dive on the newer fork legs stripped apart after some small effort, I have layed them out as assembled so that the parts are obvious. All this unit needs is a good clean to remove deposits and re-assemble. The o-ring between the fork leg and the anti-dive bodies were OK so no additional costs needed.
To left are all parts cleaned, accounted for and oiled ready for re-installation.
Note: The new genuine seals came with the bike, supplied by the previous owner who thought that was all that was needed to get the bike back on the road!
December 2006 - Fork Rebuild
The forks came back from the hard chrome works the friday before Christmas. They did a great job - replacing an internal damper piece that is installed in the factory and removing all the pits and the giant rust spot where the seal was. I was now ready to re-assemble once christmas and holidays are out of the way.
January 2007
A chance phone call turned up a set of forks from a 1985 GPz, I disassembled them and they were pretty good except for the hard chrome which was worn. I had just had a set done for the original forks and had not yet assembled them so the timing was good. I was working on the z1000A2 front end this month so the GPz tubes were still wrapped in the bubble plastic ready for assembly.
I measured all the springs against the dimensions in the service manual and everything was in range. So with the springs in the newer set of legs being perfect for reuse and the TCV and damper assemblies being good, I did a complete swap using the new tubes. The only problem was the anti dive on both units were siezed so these required disassembly.
11 February
Work on the GPz fork re-assembly begins, with all parts accounted for the damper assembly is put together for a test fit then the small damper spring is insert followed by the damper rod then the TCV (Travel Control Valve). The large spring is installed to hold it in place while the small wavy washers (3 all up) and alloy base piece are installed.
Once the damper parts are on, the lower bush is installed into its place with the upper bush,oil seal ring, and oil seal slid down the tube for insertion, I put a small amount of fork oil on the legs to enable everything to slide without scratching etc.
I installed the fork tube into the lower leg and then used the 8mm allen key to seat the socket head cap screw that holds the two parts together. To stop the spring popping up all the time you can assemble the bolt into the top of the fork, Before screwing it in I put some chrome anti-sieze compound on the threads which should have been cleaned with tissues before assembly. Once the anti-sieze is on I used the air impact gun to get the bolt down and to the right depth. Now the bottom cap screw can be screwed tight using the air tool.
The final part of the assembly is to seat the oil-seal into place. To do this without damaging the seal was going to be interesting till I realised that a 40-50mm of PVC tubing would fit over the tube and sit square onto the metal washer that sits on top of the seal (the cirlip sits on this washer to hold it all together). I put some oil on the seal and the alloy seat that it rests in and a gentle press down with the tube put everything in its place. Only need to fill the forks with oil and assembly the anti-dive.
Filling the oil
There are stacks of ways to fill fork oil without taking the forks apart. The GPz's with anti-dive make this even easier. Just remove the anti-dive from the leg and pour the oil into the top and bottom holes. You will get most of the oil through the bottom hole as the top one fills the area under the damper valve which will fill to capacity. I use a beaker from an old chemsitry set. The manual say 298ml +-4ml, so 3x80ml + 1x60ml does the trick on clean oil free forks.
Once the oil is in, bolt on the anti-dive and slide on the dust seal over the top. The fork is ready to re-install into the triple clamps and the connection of the actuators can be done.
I have not yet fixed the actuators so these will com later.. the damm things are sized solid so a stint in the over at 185C for an hour might do the trick!
Front Wheel
During the week the pool pump seized. It had been making this typical noise a bearing makes before it destroys itself, luckily the thermal cut out caught it in time, which was about 5 minute intervals (for two weeks ;) but finally I decided to pull it apart, as it sat on the bench I decided that the GPz front wheel possibly needed bearings as well since the lack of maintenance on the forks was a good indicator for the state of the rest of the bike. I also needed some for the z1000A2 rear wheel and sprocket carrier. So I gathered all the dead bearings together and rode down to SKF, $70 in bearings later I had the rest of the day filled doing bearing installations. The GPz uses the same bearings in the front wheel as the Z1, Z1A, Z1B etc (front wheel bearings are SKF part number 6203-2RSH). Common sense was in abundance at Kawasaki that year.
Once the old bearings were out of the wheel hub I cleaned all the accumulated dirt and grease from the hub and rim and pushed the new set of bearings into place with a piece of timber, a socket of the same size and an old bearing to get the depths correct. I also removed the disks as this is the big ticket item I need to fork up for before I can get it registered.
19 February 2007 Status Report
At present the forks are done and the wheels are clean with new bearings.
I need both front disks and the rear disk - $500 for full set.
I need to repair the anti-dive actuators or get new ones.
There is a crack in the bracket that holds the oil cooler so a spot weld with the stick welder will do that. Since the weather is crap I'm going to do that now.
Assemble forks into triple clamps and mount switch gear back as well as instruments. I picked up a new dash for $5 on eBay – it looks good and was a steal once I convinced him to ship it to Australia.
I need to powder coat the fairing brackets as I have a few other items that need coating so a bulk lot would be better and will only take 3 days to turn around.
Re-install fairing parts – 2 days of careful work and testing of electrics.
Replace rear disk and wheel bearings, examine rear suspension - $15 bearings
Tune carbs and work on engine.
Recover seat - $80
Hmmm... there must be something else?
15 March 2007
I found some time to work on the bike this week so I installed the forks and the air equaliser pipe and secured the clipons down. In the process I removed the assembly that holds the radiator and oil cooler as it is cracked. I dropped it off at Crosby Engineering to get a pin turned up and installed into each broken part and get the broken pieces brazed back on (the stick welder trick didn't work).
I also disassembled the fairing bracket that holds the headlight etc and will drop all the brackets in to get powder coated satin black next week.
As part of the overhaul I have had the callipers sitting on the bench, so I pulled them apart and stripped the paint of them, it was showing 23 years of wear so a vapour blast and clear coat will return them to a respectable finish. I intend on getting the pistons, callipers and mounting hardware blasted. If all goes to plan I should have most of the front end assembled by next weekend. I also need to get the seat recovered so lucky for me the guy who does the seat recovering is next door to the vapour blasters!
April 2007
Some progress work on the GPz this month! The faring brackets are back on, but I forgot to get the headlight trim powder coated so it will come off soon when I get some other brackets coated. Other than that, the assembly went well. I replaced all the old bolts with new 304 Stainless and used some chrome anti-sieze when assembling them back on. Just need to put the rest of the bits back on (Instruments, radiator). I located a supplier for the screens and I removed and cleaned up the Right Hand Side foot peg bracket (it also holds up the rear seat frame). It went in to get vapour blasted and came back brand new. There was one broken bolt on it but I drilled it out and re-tapped the hole.
The bracket is now clear coated in a new two pack marine varnish manufactured by a company called "Hemple". I was not able to get the Northane clear I used last time. While I was clear coating the bracket I did a few other items for the other bikes. The RHS bracket is now back on and all fasteners replaced with 304 stainless. In the photo below the calipers are also getting the clear coat treatment. I have been chasing rebuild kits for them this month, two sources found so far but the currency conversion rate makes it quite expensive so far. Will have to bite the bullet and get 3 caliper re-build kits soon.
I have since removed the LHS foot peg bracket and it looks like there is 20+ years of grease and grime on it and the swingarm (I scraped off 1cm thick blobs of black sticky grime). A fair bit of work is needed to clean up all the bits and pieces. Grand plan is to remove the Uni-Trak suspension and swingarm to check and replace the needle roller bearings. Also I want to clean up the parts (vapour blasting them) and clear coat them. The shock absorber is in an unknown state in terms of oil and damping capability at this stage so once it is off I can get it serviced and fit it back knowing its A1.
I decided to remove the right hand side foot peg assembly and clean all the parts down. First I stripped off the old paint then removed everything down to the individual pieces so that they could be vapour blasted back to new alloy. Afterwards they will be clear coated.
Update Once the assembly was installed on the bike the play in the gear change level proved to be quite excessive and a new bush and rose joint was installed to stiffen everything up.
Parts hanging up ready for clear coating. The GPz calipers, some brake joining pieces and the foot peg bracket as well as some z1000 and z1a parts.
August 2007
I have moved the brake re-assembly to its own page, you can visit the GPz900R brake assembly page for more information.
Body Work Begins!
September 21 2007
Today I took a few pieces of bodywork down to ATTAC Motorcycle Paint at Underwood. I decided to start with the rear end parts as I have taken the rear end off to get to the shock and swing arm which I want to strip down and get cleaned and clear coated. This photo shows the condition of the paint work of most bikes form the early 80's that have been neglected. The clear layer over the decals has cracked away and the decals need to be replaced during the repaint. I expect to see a Standox base coat and about 4 coats of clear get applied to this piece once it is complete.
Here is the tank and rear section before loading into the ute for the trip to the painters. The tank will be dropped in when I collect the rear tail section and side covers. The tank is showing the clasic wear pattern from the riders legs and the rust that builds up. The painter will acid clean the tank and then silver solder the holes before using either Kreem or POR15 to coat the inside of the tank prior to painting.
In the background is the z900-A4 which will come of the road once the GPz900 is completed.
Of these four piece the right hand side cover at the top left is in near perfect new condition as was given to the graphics firm to reproduce the decals to the correct colour and so that the painter could match the color as perfect as possible. in all the tail piece and two original side covers will be painted.
To help make removal of the swingarm easier and because I was curious at the time I decided to drop the rear end off and see how it was assembled, it is certainly a different design from the earlier z1 - z900 machines. Interestingly enough the detachable rear end concept lasted nearly 2 decades but nearly all modern superbikes have gone back to a solid frame from head to toe.
I have stripped the swingarm out and it went to get vapour blasted with a host of other parts, below is the rocker arm after cleaning and clear coating (wait till you see the swing arm ;), showing the arrow marking that indicates the bit that points to the frame. There are 10 bearing in the swingarm assembly so a trip to CBC next week to buy them and the new bearing press I bought the other week will make installation a professional job, much better than a hammer and a block of wood (or socket)!
If you have seen one bearing press then you have seen them all. In this case the smaller bearings push in with a flat plate with no issues. For the swingarm bearings I am getting a special tool made up. I'll put the details online when it is finished. I usually use a small amount of oil on the bearing so it slides in easier. A correctly fitting socket can be used to seat the bearing at the correct depth. This bearing press has a 6ton bottle jack, I can swap in a 10ton if I need more grunt :).
I used the digital verniers to measure how far I pushed the bearing in, then just measured the other side to work out the difference. I found I was out by around 1-2mm on my first attempt.
The bearing needs to sit central so that the outer covers can sit in place (Part number 92049). Put heaps of grease in before you push the pin in and push then covers into place.
This is the assembled rocker arm, the middle pivot point has two bearings in it from memory they are HMK2015. The end bearings are HMK2025 the arms themselves also have HMK2015's fitted (not shown in picture as they are on back order :).
The swingarm requires four (4) of the larger HMK2530 bearings. There is no grease nipple in the GPz900R swingarm which I think is a clear design fault. There appears to be room to modify it to fit one so I might do this on the 1985 zx900A2 I have in storage. The assembly of the swing arm bearing is Here.
In total you will need: 2x HMK2015 and 2x HMK2025 for the pivot piece, an additional 2x HMK2015 bearings for the arms and 4x HMK2530 bearings for the main swingarm pivot. Thats 10 bearings in total!
November 11 2007
Just received the rear disk (Metal Gear brand) and I have started to assemble the front end complete with calipers and brake lines. Not shown in the picture is the anti-dive actuators which I assembled on later.
I will be pulling out the rear shock and re-filling the oil (200ml 10W). Once this is done it will be re-installed with the Uni-Trak rocker arm, when the rest of the bearings arrive for the swing arm this week I will be pushing them in using the new tool I am having made. The rear caliper pieces need to be cleaned, so these will go out during the week. The rear wheel will be fitted shortly after that.
November 18th 2007
Had a productive weekend, managed to find some time to complete the assembly of the front brakes, first I cleaned out the master cylinder and then put the bleed nipples in (all 6!) before bleeding some new fresh brake fluid into the system. After about 30 minutes the brakes were bled and worked fine with no leaks. Also flushed the clutch out but will do both systems again during the week to get any remaining air out of the system.
Also fitted the rear shock after the oil change and cleanup as well as fitted the Uni-Trak rocker arm. The bearing tool I want to use to push the swing arm bearings in with is still getting made, it should be ready this week so I can do a precision job on the swing arm. While I was fitting out the rear I cleaned up the back of the motor removing the thick grease that had built up over the last 23 years and re-fitted the side stand switch.
The only hold up on the rear end is the caliper and mounting arm, I have two spare calipers that are ready so I will use one of them and the brackets just need cleaning. The paint work still has not arrived yet! Must call Graeme at ATTAC and find out what the holdup is. Dropped the top fairing in the other week but the decal for it has not been made.
The swing arm has been vapour blasted clean, in the process it was discovered that it had a coating of some kind that was resistant to paint stripper. As a result it took a lot longer than the quoted time to clean it but the result is fantastic. It has now been coated in a marine clear to protect it. Also shown are the rocker arms with new bearings now installed.
November 29th 2007
I received my new tool to press the swingarm bearings in. I had to wait a week for it as the guy who machined it was flat out on other jobs, but it was worth it as the bearings went in perfectly and I now have a tool that I can use on my 1985 GPz900 when it comes time to rebuild it.
Hopefully this weekend (Dec 1st) I should be able to get the swing arm installed and the rear wheel back on. Then I will be wheeling the bike into the garage for some final assembly work and for some work on the engine. I'm not keen to remove the carbs while the engine is outside.
Engine work begins
Boxing day 2007
Rather than stuff my face with Christmas leftovers I decided that some time working on the GPz motor would be well spent. The only fault that I am aware of in the engine is the starter clutch. So after reading the manual numerous times and picking the collective brains of the GPz owners club in the UK. It was collectively decided that the starter clutch can be removed by tipping the engine upside down and splitting the cases without having to strip the head and barrels. Full story Here
Update November 2009
After 18 months of running I did a valve clearance check this weekend, to my surprise the clearance is spot on and there is no wear on the cams, they still look brand new!
One thing you don't want to find is metal pieces, this one is large enough to concern me but I can't find the actual place where it came from?
A selection of interesting motorcycle books you should own at Amazon.com I picked them because I own many of them and others have been recommended to me.
