JVCycles - 1975 Kawasaki Z1-B Restoration Project - SOLD

I've done many restoration projects before that include a 69 Camaro Pace Car, a 1956 Ford F100, a 95 Ducati 900ss, and a number of Japanese motorcycles, but never a restoration this involved. I was looking for a bike that would need a major restoration and that I’d only have to pay $100 or $200 for..  My goal with this project is to is to have an award winning Z1-B.

Today I brought home what is probably the biggest motorcycle restoration project I have done to date. A lot of people would have left it in the field, and maybe I should have, but I enjoy bringing life back into a once powerful and stylish best of breed motorcycle. The good news is that it the price fits into my budget for this project.

 The Teardown

 I washed the bike to remove the grease and loose dirt. I used engine cleaner and SOS pads. The SOS pads seemed to do a good job of making the aluminum cases and forks look better. But in this case more drastic measures will be required.  I also cut and removed the aftermarket exhaust and threw them into the garbage can.

Today was the first day of tear down. First the seat and tank were removed. Both the seat and the tank came off very easily. There was a lot of surface rust and corrosion. We'll deal with that later.  From this point forward, all the parts will need to be bagged and labeled, and the wires labeled when disconnected.  The entire wire harness for the turn signals and the stop light can now be disconnected also.

Next, I removed the rear fender and plastic tail. The front of the rear fender was held in place with tabs that were attached to the frame. The rear of the fender was attached with bolts and rubber grommets. I disconnected the stop light and the rear turn signals.

Once the fenders were removed it was time to remove the battery box. The battery box was held on by 2 bolts on the top and 2 rubber mounting brackets. I had to remove the voltage regulator mounted under the battery box also.

The last components removed today were the carburetors. I loosen the clamps holding The the intake manifolds and remove the throttle cables.

The next day I got busy and removed the wheels, front forks, headlight and remaining wiring harness. The last item of business is to remove the engine. Don't try this by yourself, as I did! This is one of the heaviest engines ever made, at least the heaviest motorcycle engine I have ever removed. I tied straps around the engine and to the strongest garage rafter I could find. Basically I suspended the engine and removed the frame from around it. This is not the way to do this.  For future reference, the correct way to do this is to drain the engine oil and lay the engine and frame on their side.  Once the engine is supported, unbolt the engine mounts and lift the frame from the engine.  This method is much safer and easier on your back.  It would help to do this with two people.

A piano dolly made a great engine cart.  Make sure to tie the engine to the dolly with straps. As you will find out the engine wants to roll forward. 

My Z1 no longer looks like a motorcycle. The once great Z1 is now reduced to a bunch of plastic containers, a frame, wheels, and a very heavy engine.

The Frame

The base of any restoration project is the frame.  Cut corners here and you’ll pay for it later. There is a lot of debate on the web regarding the use of paint or powder coating for the frame. It’s a personal choice and I choose to go with powder coating for it’s durability.  The next step is to prepare the frame for powder coating. On the front of the frame you'll find the VIN number stamped in the frame and just in front of that you will see the factory manufacturing sticker. I gently removed the paper sticker with a razor blade. Even taking my time and going very slow didn't stop the sticker from developing a tear. After I taped the sticker so the tear would not continue across it, I then scanned it into my computer. Using Microsoft Paint, I was able to clean up the image of the sticker and print it out on regular paper. The plan is to find a weather proof clear sticker that can cover this new one and reattach it to the frame once it returns from the powder coater. However, at this point it's only a plan. Maybe I'll find a better solution once I get closer to finishing this project.

Powder coating prices vary a lot in my area. Make sure you find a powder coater that is familiar with motorcycle restoration. Ask them to see samples of their work. Once I decided on a Powder Coater I brought the frame, engine mounts, and triple clamp to them for coating. Another decision you'll need to make is what color of black you want the frame and parts coated with. As you will find out the factory frame paint wasn't the best paint job in the world. Even though it was considered gloss black, the preparation, or lack of it, made the frame appear to be painted semi-gloss or satin black. They refer to this as 60% gloss black in the powder coating world. I actually selected the gloss black powder coating after spending over a week looking at samples and reading forums on the web.

The Engine

After weeks of searching, I decided to bring the Z1 engine to Spears Racing, www.spearsenterprises.com , in Manteca, CA. Owner, Gregg Spears was recommended to me by another Z1 collector who had Gregg rebuild his engines. The engines I saw were beautiful. Before bringing the engine to Gregg, I removed the side covers so they could be cleaned, sanded, polished and painted with a coat of clear. I'll cover that process later on.

Once Gregg was able to tear down the engine he determined there was a crack in the lower case. It happened to be right under one of the main bearings, which made it almost impossible to weld and very expensive as well. I found a set of cases on eBay for $75. Once the "new" cases arrived at Spears Racing, they were sent out to be cleaned at a local machine shop. The cleaning didn't remove all the dirt and grime from the cases, so I brought them home to work on them some more. I also brought home the cam chain tensioner, engine pan, kick starter housing, and another piece from the rear of the cylinders to be cleaned, sanded and polished.

We also decided that the cylinder block was too corroded to get fully cleaned. So back to eBay I went. I found a good cylinder block that was still the standard bore size. Gregg had to replace a couple of the iron cylinders with cylinders from the original block.

After spending many hours with a brass wire brush, steel wool, SOS pads, Super Clean, etc., the cases and the cylinder block were ready to be painted.  To paint the cases and cylinder block I gave Gregg two cans of Harley Davidson silver case paint, part number 98660-78.  The process we used to paint the cases consisted of the following.  First make sure the parts are clean.  We used dish soap to clean and prep the parts for painting.  Once the parts are clean and dry, heat the part to 350-450 degrees.  While still hot, apply Harley Davidson high temperature silver paint.  By applying the paint hot, the adhesion is improved.  Allow the part to cool to room temperature.  The second coat of paint is applied at room temperature.  This application will give you the shiny deep silver finish that you desire.   After 24 hours, heat the part to 225-250 degrees for one hour.  This final step will cure the paint and toughen it.  You’re now ready to assemble the engine!  It looks great!


I purchased new spokes from Z1 Enterprises,
 www.z1enterprises.com . Before the new spokes can be laced onto the hubs, the hubs need to be separated from the rims and cleaned and polished. Take a picture of the spoke pattern before you separate everything.  It will come in handy when you start to lace the rims.  This next part was actually fun! Rather than unscrew each rusty spoke, I got my bolt cutter and cut each spoke. This separated the hub from the rims fast. I set the OEM rim aside to be cleaned, sand blasted and powder coated black.  The rear hub was then cleaned, sanded and polished before being painted with clear paint. The front hub was cleaned, sanded and painted satin black.

I got the rims back from powder coating.  After painting the hubs, I removed the bearing (3 on the rear and 2 on the front) and seals, and replaced them with new ones from All Balls,www.goallballs.com

Once the hubs were completed I started the process of lacing the wheels. When you buy spokes there are two or more bends in each package.  Make sure to use the spokes bent greater than 90 degrees on the outside of the hub and the spokes bent at 90 degrees or less on the inside of the hub. There is a great video at Garage Night (see episode #9), www.garagenight.tv , to help explain the entire process. I found this show on iTunes in the Podcast section. It could be one of the best finds yet! Back to lacing. The process takes
time, but I didn't find it very difficult at all.


The carburetors had some bad corrosion on the body where the main jets screw in. So once again, to eBay I go. Carburetors are in demand for these bikes. I won a bid after trying a couple of times. Expect to pay anywhere from $80 to $200 for a good set of Carburetors. You will probably need to buy a gallon of carburetor cleaner. I got mine from Napa Auto Parts. I soaked the new Carburetors for 24 hours, but depending on the shape of the Carburetors, your time may vary. Once they were blown out with compressed air, I installed carburetor kits from SUDCO.

Update: Since I wrote this section I have decided the best practice would be to not use the NAPA carburetor cleaner.  It left the carbs with a dull finish.  Since then I have rebuilt a number of GL1000 carburetors and cleaned them using Simple Green to remove the dirt and grime and spray brake cleaner to remove the stains and clean the passages.  They come out much nicer looking.

Tank and Body Parts

The tank, side pods and rear tail piece looked to be in reasonable condition.  The tail piece has a couple of “dents”, one on each side and the side covers look to be free of cracks but one is missing a mounting tab so it will need to be replaced.  The tank has surface rust inside and body filler hiding a small dent on the top of the tank.  The biggest problem seems to be that of the four tank emblem screws, one on each side has broken off almost flush with the mount.  This problem needs to be solved before I go any further on this tank.   I like to use Kreem Tank Liner and Prep. to seal the inside of the tank.  The process is a three stage process.  I’ve found that it helps to dilute the third step with some of the chemical from the second step.

I’ve ordered the paint from Paintworkz (www.paintworkz.com).  Ralph is very helpful. 

Update:  I still have the paint mentioned above.  The Z1 is all black!


I decided that the fork tubes were too pitted from the rust for my restoration.  I ordered a fork kit that included new fork tubes, spring and new chrome headlight mounts.  Once the forks were apart, I used the aluminum polishing process, described below, to restore the dull aluminum fork bodies.  I finished up the fork restoration with new fork dust covers and new top fork plugs. 

Polishing Aluminum

This is not for the faint of heart  . . . Start by cleaning the aluminum piece with dish soap to remove all the loose grease and dirt.  Next, fill a bucket with warm water and dish soap.  You will use this for the wet sanding.  Depending on the condition of the piece you start with (120, 240, 400 or 600 grit) wet sandpaper.  I started with 240 or 400 and sand the piece completely because or the poor condition of the aluminum.  Next sand completely with 600, then 800 to 1000, 1500 grit wet paper.  The final sanding is with 2000 grit paper.  After sanding, you can go straight to the polish wheel or go over the piece one last time with “0000” steel wool.  You can stop now if you want your part to look more like the OEM finish.

Polishing is the next step.  This step will bring the shine out in the aluminum piece.  I use a 6” bench to polish with a polish wheel at each end.  You don’t have to spend a lot of money on these polishers.  I found mine at Harbor Freight.  Do not buy your polish wheels at Harbor Freight.  They are made cheaply and fly apart very fast.  For a little more money you can get good wheels at Lowes.  You will start using a coarse polishing compound and finish with a fine one.  Do not use more than one compound  on the same wheel.  Once polished, clean the piece with acetone.  I sprayed mine with a clear paint to look more like the original pieces on the Z1.  It is a personal preference.  If you decide not to clear coat the pieces you will need to apply aluminum polish every few months to keep the shine. 

The Assembly

Once the engine was completed (it looks fantastic!), Gregg helped me mount the engine to the frame.  The easiest way to do this is first to wrap the frame around the engine area with water pipe insulation. 

I used the insulation made for 1” water pipe.  Next, place the engine on its side and brace it with wood blocks so it is stable. Once you are sure the engine is stabilized, lift the frame, then turn it on its side and lower it slowly down around the engine.  You will need help.  This is a two-person job. Find your freshly zinced engine mounting bolts and secure the engine in the frame.  This process is much easier than lifting the engine into the frame!

The next steps in the assembly process will be to attach the forks, the swing arm and the shocks.  Before installing the triple clamp, I replaced the steering ball bearings with new roller bearings from All Balls (part # 22-1014)   I removed the bearing races from the frame with a brass punch and hammer.  The inside race on the lower triple clamp wasn’t so easy.  I had to use a Dremel Tool to grind out a “valley” in the race.  Once the valley section was removed, the race was easy to tap off.  I installed the outer races on the frame and installed the lower steering bearing (the bearings are different for top and bottom) on the lower triple claim.  Before installing the bearings on the triple clamp, make sure you sand off the power coating from the clamp portions of the triple clamp.  You don’t want that stuff in your new bearings.  I test fit the new fork tubes before installing the triple claim on the frame.

Once the front fork are in place it's time to turn my attention to the rear of the bike and the swing arm.  The swing arm bushings gave me some trouble.  Before I had the frame powder coated I removed the swing arm bushings.  I then bought new inner and outer bushings from Z1 Enterprises (www.z1enterprises.com).  I pressed the outer bushings into the swing arm.  But when I tried to install the inner bushings, they were too large to fit inside the outer bushings.  To make a long story short, I had to have the inner bushings turned on a lathe to remove 7 thousands of an inch.  Once the excess material was removed the swing arm was easy to install.

Lacing rimes isn’t as bad as it looks.  Once you get the pattern down it just takes time.  After the rims were laced, I trued them with a make shift rim jig.  It consisted of 2 jack stands to rest the axle on and a coat hanger as my gauge.  Not pretty, but it works fine.  

The Z1 is starting to look like the bike it once was.  Powder Coating the rims and front fender gloss black really gives the bike a different look.  

Next, I move my focus to the battery box and wiring.  The battery box, that was powder coated black with the frame, and was installed using stainless steel Allan head bolts.  I know it's not original, but I really like the "high tech" look.  Because I cleaned and re-wrapped the wiring harness earlier, the installation was easy. 

I've also decided to remove the black from the handlebar controls and master cylinder.  They give the bike a much different look and feel.  Again, this is not concourse anymore, but I like the look!

The gauges were the next area to tackle, but the gauges like the rest of the bike had seen better days.  I decided to send them to Bob Harrington at Z-Resto.  The gauges came back looking like new.  They turned out fantastic!

I ordered new Throttle and Clutch cables.  When they arrived they were way too long.  The new Drag Bars needed much shorter cables.  So... I heated the carburetor end of the throttle cables, which melted the solder and I was able to remove the cable end.  I then had to shorten the cabled shield.  Bicycle shops make cable cutting tools that make the cutting so much easier than the ol hack saw method, which never works.  Once the cable was cut and lubed the cable put it through the shield and cut it to length.  Bend a 90 degree angle in the cable and re-solder.  Good as new!  

Painting the Tank, and Plastic Body Parts.

The tank was completely stripped down to the metal and then sanded with 80 grit paper.   The tank and tail section need a small amount of body filer.  The side covers are new. 


After the tank and tail section were sanded and primed, they were all block sanded, painted and then block sanded again until no waves could be seen.  I was going to use decals (very expensive decals I might add …$90) from Reproduction Decals in Canada.  Problem is they are very hard to apply with creasing them.  So I painted the gold and white stripes on the tank and tail section.  The entire paint job was covered with a clear coat.




One of the toughest decisions I've had to make on this build is what exhaust to use.  There becomes a point where you need to look at the value of the project and not continue to throw money into it.  I really wanted the OEM style exhaust, but decided that the cost ($1,600) was just too much and I would never resell the bike for what I have invested.  Plus since the Z1 was now a “custom” the 4 into 1 exhausts made sense.  I went  with Vance and Hines exhaust from Johnny's.  The price was right and the people at Johnny's were very helpful.


Rear Fender (or lack of one)


I decided to keep the rear fender on the shelf.  This meant that I would need to make a bracket to hold the tail light and license plate.  I make the bracket adjustable was I could adjust the tail light for the best look.


The Z1-B is back on the road!  Over 2 years of on and off work turned out a very fast mild custom Z1-B.



        SOLD July 2013