View Full Version : Beware of the Assassin: 900 Ninja Lives

10-07-2010, 09:24 PM
You might get a kick out of us breathing new life into a 900 Ninja I built years ago, and after a spill sat for a long time in the garage. Its kind of like getting a new bike all over again:

Beware the resurrection!










My brother (DoctorDR) and I did some amateur road racing in Seattle Wa. from 1984 to 1990.
The bike shop I where I worked sponsored us and helped build my brother's Battle of the Twins winning Kawasaki EX500.


When DoctorDR moved to Austin, TX in 1991 to attend university, he worked at Quadracycle and built up the mighty Ninja 900. The motor has a big-bore kit, ported head, flat slide carbs, race pipe and a fortified tranny and clutch.
The result was 120 hp at the rear wheel, and it hit 160 mph at red-line in top gear.


The bike shortly after it was built.
Heavy duty cyl studs
- Heavier valve springs
- Deburred head casting
- Magnafluxed and race-cut transmission
- Balance, bore, hone, fit pistons
- Balance, polish crank
- Polish, shot peen, balance rods
- Billet clutch hub
- New clutch plates
- Race ported head, radius valve job
- New valves, guides, seals
- Wiseco 972cc piston kit
- Mikuni RS36 D8-K race carbs
- New chain tensioner, alternator chain,starter chain
- D&D Show and Go header
- Fox Race Shock

The bike pumps out 110 hp at the rear wheel.


This engraving on the Performance Machine brake disk leads me to believe the wheels were
assembled in 1993. So the bike was built up at that time.



After about 15,000 miles of riding the Ninja was put in storage after a small spill *which resulted in a bit of road-rash to the bike. So, it has not been running for over 10 years. Here it is as delivered to the Man Cave.


The plan is clean, inspect and lubricate the suspension, mount new tires, change fluids, new battery,
rebuild carbs, and try to fire it up!


I removed the disks in order to polish the wheels:


I painted the upper and lower triple clamps, handlebars, bar end weights, and polished the muffler and the fasteners for the disc brakes.
Next up is cleaning, inspecting and re-bushing the rear suspension linkage. *:beer



Ok, I installed new needle bearings in the swing arm and shock linkages.
All the parts painted nicely with Duplicolor brake caliper paint - very durable!
Next up, assembling the rear suspension!


Fox Twin-Clicker in all its totally rad rock and roll colors!

I polished the wheels and clear coated them with Eastwoods wheel paint.
New Pirelli Sport Demons round out the package.

No cush-drive, the sprocket bolts directly to the hub. This bike is gonna kick butt.

The rear suspension and wheel are coming together nicely.



Scored a nice fairing off of e-bay for $130, no cracks or road rash! *These are hard to find without the turnsignal mounts broken out because the signals are the first to hit the ground if the bike gets laid over. *For now we might just rattle can it red to get it mounted on the bike.



Will keep you posted on developments!

10-07-2010, 10:24 PM

10-07-2010, 11:53 PM
Tim, thanks and that's a great blog you have there.
The old KZ's were the bomb, big bullet proof motors for sure. As a teen I grew up in awe of the original KZ900 this crusty old mechanic had a bike shop. He put thousands upon thousands of miles on that KZ. I remember that root-beer colored paint with the orange pin striping!

Will keep this post updated as we make progress on the now "classic" Ninja.


Vic CC rider
12-25-2010, 11:56 PM
Love that bike, I have her lil sister.

05-08-2011, 07:15 PM
Well, the Ninja is starting to look like a motorcycle!
I mounted the fairing, mirrors and signals, tidied up and plugged *in the wiring harness.

I repainted most of the motor and painted a side cover.

The fluid in the clutch master cylinder was cloudy and had some grey crud floating in it, so I re-built it.
The front and rear brakes will get the same treatment.

05-08-2011, 07:53 PM
This is an awesome project! Keep it coming. I love my 900.

The Bruce
05-09-2011, 08:48 AM
:coffee: Nice! The Kaw 900 was my brothers favorite bike when he was able to ride.

05-09-2011, 10:49 AM

05-09-2011, 11:14 AM
That was and still is a really cool bike!! Looks good.

05-19-2011, 10:08 PM
I painted the clutch cover with high temp engine paint and applied the new emblem.

Got the ignition cover painted and the new emblem on it too.

Installed the chain and chain guard, and torqued the axle bolts... the rear is ready to go!

05-19-2011, 10:18 PM
Man...... You are really going to enjoy riding that bike again. ;) I know I would.

05-20-2011, 08:45 AM
Brilliant, I bought a blue & silver one in Europe when they first came out.. Loved that bike but ended trading it in for a new CBR900RR!! You are doing a great job there..


05-23-2011, 09:26 PM
More bling! Used tank from ebay, $150 including shipping....no rust inside. SCORED! Yes, it will get painted, kind of a shame....but the body work I have is from three different bikes, three different colors! This will save from dealing with dents in the original tank.



05-25-2011, 11:07 PM
More Ninja bling! Scored most all the body work I need from E-bay, really great seller that took a lot of care to pack all the parts well so they were not damaged in shipping. Prices were great! So, in addtion to these parts, have side covers and tail section coming. Am missing front fender (pearl white) and main fairing. But, painting the good main fairing I have is pretty straight forward. I have a line on a front fender from a breaker shop, will have to see what condition its in. This body work has a few scratches and cracks, but overall, for a 25 year old bike its in great shape. Even better than the body work I already have. Also, have the plastic trim inserts that go in the belly pan.....a rare score! I think most of these parts get tossed. So, I have ALL of the fairing inner trim parts!






Shows hard to find trim parts for belly pan.


05-26-2011, 09:22 AM
:popcorn: We want more :photo::mrgreen:

1 wheel peel
06-02-2011, 02:11 PM
Keeep it coming.:clap:

07-08-2011, 09:37 PM
Well, ebay has been an awesome source of parts for our Ninja project! We are installing lots of parts from one bike that is being parted out on ebay. It is a low-mileage 1995 model in Red/White/Blue that is providing the following:
Rear sub-frame
Rear tail piece
Rear fender
Side Panels
Lower fairing
Belly pan
Front forks (complete with triple clamps)
Front fender
and various small parts.
We have assembled the rear sub-frame and tail piece and rear fender.
There will be some repairs needed to some minor cracks in the bodywork, but the original paint is very nice.
The front fairing will be painted in original factory colors to match the rest of the bike.
Also, we may swap the Corbin Gunfighter Lady seat for a solo Gunfighter.
Because this bike is for flying low! *:ricky :ricky




This evening I rebuilt the forks with new fork bushings, seals, race-tech goldvalves and specially machined blocks that replace the funky anti-dive system. This weekend I should have the entire front end assembled with the front tire installed. *




1984 GPZ 900 Ninja Restoration Project Costs to Date

- F/R Tires, mount and balance. 120/70-17 front. 140/80-18 rear. *Bias ply. *Upgrade to larger 150/80 rear later. $300
- Misc spray paint, brake fluid, polishing compound, rear suspension bushings and bearings, swingarm chain protector. $300
- Entire front fork assembly with triple clamps and bearings. E-bay from bike w/ 20K miles. *$105
- Fork lower legs. E-bay, purchased to replace original fork lowers but not used after getting entire fork. Will re-sell. $40
- Used lower triple clamp. E-bay. *Wont use, got better one with complete fork. $30
- Front fork lower bushes. Bike Bandit. *$53
- Front fork upper bushes. Bike Bandit, ordered extra set by accident, will sell on E-bay. $30
- Machined alloy block off plates for anti-dive. E-bay. $80
- Used handle bars. E-bay. Originals were tweaked. $25
- Used tank. E-bay, bike w/ 20K miles. $175
- Used mid, lower, belly pan fairings, side covers, rear cowling, front fender. E-bay, bike w/ 20K miles. $204
- Used upper fairing. Black/Grey/Red, will re-spray to match Red/White/Blue of other bodywork. *Original had busted out signal mount. $150
- Used rear fender assy. E-bay, bike w/ 20K miles. $15
- Used upper, mid, and lower fairing inserts. E-bay, bike w/ 20K miles. $85
- Used upper fairing mount. E-bay. Original was tweaked. $60
- Used upper fairing access port. E-bay $20
- Used rear subframe. E-bay, bike w/ 20K miles. *Original was tweaked. $22
- Used mirrors. E-bay $15
- Misc hardware, spacers, rubber grommets, exhaust gaskets, new Kawasaki emblems. Bike Bandit. $242
- OEM new front turn signal. E-bay $35
- Misc used turnsignals. E-bay $30
- Used kick stand. E-bay, bike w/ 20K miles. $14
- Used fuse box. E-bay, bike w/ 20K miles. $18
- Used gas cap, ign switch, lock set for entire bike.E-bay, bike w/ 20K miles. $43
- Clutch cover gasket. E-bay $9
- New Bikemaster gell battery Pink Gorilla Cycles, Austin. $85
- Plastic repair kit. Eastwood restoration supplies. $40
- Misc E-bay shipping charges. $84
- Carb rebuild o-rings, pilot and main jets. $90
- Oil, coolant, spark plugs. $90
- Corbin Gun Fighter seat. $390

Minus misc parts sold on Ebay ($230)

Total to date: $2,614

Upcoming costs: paint for fairing

Installed the forks, repaired cracked fender, rebuilt brake cylinder, installed brakes, torqued axle and its ready to rock!






07-09-2011, 03:08 PM
I am fitting the body work to the bike, this is a trial fit to get the fasteners sorted out and make any adjustments to the mounting brackets.
It will come off again for some crack repairs, then a final mounting to the bike.
We will also be painting the upper fairing to match the rest of the bike.
It is rather lean and sporty looking, if I do say so myself!


07-09-2011, 04:53 PM
Wow! I just got here and got to see the whole project from first post to now. Amazing! Beautiful job :clap:

07-09-2011, 07:38 PM

07-09-2011, 07:50 PM
Thanks for the compliments! Its coming along good. Hope to have it running in about one-two months. Waiting on a new Corbin that needs to get made. Plan to have it out at Harvest Classic for sure.

07-09-2011, 07:55 PM
WOOOHOOO! Don't stop more more more!

Mr Marie

07-13-2011, 09:10 PM
We used this plastic repair product called Plastex, and despite the rather dubious packaging, it worked really good to fix
the various cracks in the lower fairing and belly pan. Much better than JB Weld and the repair is instant.
It uses fine plastic beads and a solvent to weld cracks, fill holes and even comes with a mold for replicating parts.

I used a jig saw and file to cut out the relief in the belly pan to clear the header pipe, mounted the radiator and oil cooler.

I installed the rather hard-to-find plastic filler pieces that dress up the gap between the fairing and motor.

After some fiddling about I got the bars installed. Good thing we had two pairs on hand, as one bar was bent.

The Telefix fork brace that my brother purchased in the 1980's fit very well.

I am on to getting the electrics sorted out, I got the turn signals, tail light, brake light and starter motor working.

07-16-2011, 10:39 PM
Ok, so I cleaned the Mikuni RS Series Radial Flat Slide installed new pilot jets, main jets and cleaned the float needles. I also put coolant in the bike, cranked the motor over and checked for spark and installed new plugs.

The Mikuni RS Series Carburetors were designed and built in response to the needs of the world's top motorcycle road race and drag race teams. They required carburetors which would satisfy the precise fuel metering demands and high flow volume required by highly modified race engines. And yet, also provide the smooth, controllable throttle response that is needed by any rider pushing his motorcycle to its limits on the race track and under high performance use.

The carburetors need to meter fuel correctly under a wide range of atmospheric conditions and engine tuning modifications while being easily accessible for trackside tuning changes which need to be made quickly.

Designed for in-line four cylinder performance motorcycle applications, the Mikuni RS Series Radial Flat Slide Carburetors offer superior horsepower gains with their maximum flowing smoothbore induction tract and radial flat slide design. An adjustable accelerator pump system helps to provide instant throttle response, particularly in the lower RPM range.

The RS series Carburetors feature a compact design which is 25% lighter than other performance carburetors, offers quick needle jet adjustment, and uses readily available standard Mikuni jets.


08-02-2011, 08:41 PM
So, I got the carbs together and mounted on the bike and snapped a pic of the porting job before mounting them.



It took an hour and a half of fiddling with the new Corbin seat to install the brackets and shim them so the seat catch engaged.
The seat looks and feels great, but fits like a Corbin... meaning not perfect, but good enough. Corbin's seat pans have always been kind of wonky.

I should have put sunglasses on the Ninja, because this is the first sun light its seen in 15 years!

:clap::clap::clap:SO HERE IS THE START UP!!!!:clap::clap::clap:


The Bruce
08-02-2011, 09:21 PM
:clap: sounds sweet.

08-07-2011, 11:20 PM
Today was a great day! DoctorDR took the mighty GPZ985 Warrior to the streets, for the first time since parking it 18 years ago!
We took it around the neighborhood for a shake down run, and man, the motor totally rocks! The blue-printed engine, balanced crankshaft and pistons really shine! This is a very addictive bike!
We discovered the clutch slave cylinder is leaking, so no big ride until we fix that, but everything else is solid!




08-08-2011, 04:43 AM
Looks like a show bike that goes! Congrats on a job well done.

The Bruce
08-08-2011, 09:49 AM
Fantastic! :thumb:

08-08-2011, 09:55 AM
All that work definitely has paid off! Congratulations :clap:

08-08-2011, 02:09 PM
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08-12-2011, 12:38 AM
Sounds great, I bet it is a hoot to ride. Great job.


08-13-2011, 05:05 PM
Thanks for all the compliments, it was a labor of love! I will have it out at this year's Harvest Classic in October. Ride on dudes!

08-14-2011, 07:24 AM
Well done!!!

10-25-2011, 08:48 PM
Well after all the work on the old Ninja thought I would update you all with the great road trip me and my bro took to Del Rio! Enjoy!

We finally celebrated the arrival of some cooler October temperatures by beating it to Del Rio, Tx from Austin on our Dueling Ninjas!
This 700 mile overnight trip was a big test of DoctorDR's 1984 Ninja superbike that was recently resurrected from 18 years of storage, and the first big road trip for my 2011 Ninja. *

Here is our route to Del Rio, we spotted tons of cool bikes, like Moto Guzzis, Triumphs and Adventure bikes making their way to the Harvest Classic.

The weather was perfect for the 900 Ninja, it tends to run hot so it loved the cooler weather as we passed through the Camp Wood area.




The lunch in Rocksprings was good and cheap! The basic no-frills burger is $2.25, this one cost .50 more!
On our return through Rocksprings the burger joint was closed. So, we tried one the "biker friendly" BBQ shacks and they refused to sell us a brisket sandwich only, you had to get a drink and side, $10 - or no deal. Talk about brotherhood.



This furry critter tried to take a bite out of my arm as I was riding. At first I though I hit a bird, but went I stopped an got off my bike he fell off my lap.
He's got a cute face.




Man this old bike has a **** of a motor, It kicks in hard at 7500 RPM and pull strong up to 10,500. The big bore kit, ported heads and smooth bore carbs really get the adrenalin flowing, and its addictive!


We took a break to check out the Stuart Bat Cave at Kickapoo Caverns, not much bat action in the heat of the day, but interesting none the less!




Fun artwork in the hotel we stayed at in Del Rio, nice owner and cool place! *We were shocked to see motorcycles everywhere. *He told us
how a group of Harleys went accross the border, and on the way back two vans got between the last three riders. *Guys popped out of the vans with
guns, and told the three riders to start walking.....and loaded their HDs in the van! *Moral of story, dont take pricey HDs to Mexico!




Of course I loved the VW Bus, since I have one!


The next mornings ride was awesome! The section from Del Rio to just below Sonora was beautiful. Excellent 30 mph sweepers and rolling hills.





We were stunned to see such a beautiful river in Texas! We pulled over, removed our helmets and took it all in. We could hear a lot of wildlife in the trees lining the river.




The latest Ninja, next to its genesis. Let me tell you the apple did not roll far from the tree.
Either bike is capable of insane speeds - one in a deliciously raw way, the other in a civilized way.



Ninja's coming and going!


The Bruce
10-25-2011, 11:17 PM
Very nice. :thumb:

10-25-2011, 11:26 PM
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02-02-2013, 08:45 AM
To update this thread, I finally scored a nice 86 900 Ninja fairing from E-bay! *These are very hard to find in decent shape so I jumped on it, $280 including shipping which I think is reasonable. Otherwise I was faced with trying to get my other fairing color matched. *This one has a few minor cracks, and scratches, but I think its a an 8 out of 10!

So this will really polish off the restoration project! *I may hang on to my old one as a spare, because finding a fairing that is not faded, busted out or road-rashed is very difficult. *




02-02-2013, 10:37 AM
What an exceptionally beautiful restoration. Well done!!!

02-08-2013, 10:43 AM
Really enjoyed reading this whole thread. Can't wait to be you one day, but my project will be my very first bike, 1987 GSXR-750. Beautiful bike, I thought I was the only one who likes the looks of 80-90's sport bikes! Thanks again for sharing!

03-02-2013, 07:54 PM
Well on Texas Independence day we busted out the 900 Ninja in full Texas colors, with the matching top fairing I scored on Ebay. *With a front brake master cyl rebuild, fresh rear tire, and belly full of Mobile 1 synthetic we were ready for a days ride! *KosmikKLR on the Buell TT and our buddy Portero on his stonking knock out sexy KTM SM TOURING!

And yes I actually took *it across a wet creek crossing! *:yikes :yikes :yikes *(only after Portero assured me it was not slick)

The small single lane paved country roads around Dripping Springs are great dual sporting fare too!






The Bruce
03-03-2013, 08:45 AM

:clap: Love it!

03-03-2013, 09:51 AM
A great write up and build......thx for sharing....and all the great pics!