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StreetFighters UNITE
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Discussion Starter · #1 ·
copped this baby on Craigs list for the low.

its a 1984 kawasaki ninja 900 (GPZ900). main selling points for me are chain drive, 900cc, liquid cooled, 16 valve, short swing arm, hydraulic clutch, project peace of junk. there's got to be a million things ill have to do before it even runs.









so to begin ill be taking most of it apart to diagnose what has to be done. the first thing i notice is that the rear sus is not working properly and it looks like ill be needing a narrower shock because this one bumps against the swing arm midway through travel. wonderful...






the bike is missing a good amount of stuff including gas tank, carbs, handle bars, mounts and controls, a few electronic components like the regulator rectifier, relays and fuses. im sure this is only the beginning of a long project with a low budget, but i hope to learn a few things in the proses like mig welding and eventually a good bit of hooligan mischief in the streets.
 

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Just Here For The Party
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696 Posts
Thankfully a large majority of the early Ninja parts are interchangeable so finding parts won't be a problem. Even model specific things like tanks and fairings can fit without any modding beyond bending a new bracket or adding a few washers.

I've heard that the early 900 motor would throw crank bearings occasionally, but that was from a former boss/motorcycle hoarder who might have not wanted to sell his GPZ900 motor. Take it with a grain of salt.

Good luck with the build!
 

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StreetFighters UNITE
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72 Posts
Discussion Starter · #3 ·
So I ordered some carbs, they should be here soon. In the mean time I cleaned her up a good bit, flushed the radiator and replaced the coolant. I changed the oil, and here's something interesting.. the old oil was very thin or watery and smelled of gas. I'm quite puzzled how this could have occurred.


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also does anyone know if the 90's rear sock is compatible with the earlier 80's linkage?
the newer shocks look a fair bit better, and most likely function better as well.
 

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Hack in a barn
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4,409 Posts
Usually if the oil smells of gas the petcock on the tank is bad and lets gas flow into the carbs and then that goes into the cylinders and then it makes it's way into the case. A small amount would get in if a float was stuck on the carbs because the petcock, if functioning correctly, would only let what is in the line from the tank to the carb past. It's probably a mixture of both, but you should check over the petcock...
 

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StreetFighters UNITE
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72 Posts
Discussion Starter · #5 ·
that makes perfect sense! no tank or carbs came with the bike because the tank was rusted out or something, and PO sold the carbs, they would most likely have been completely gummed up, and way beyond functioning properly.
 

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Administrator
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PROPS to ya mate ~ old skool muscle is damm fine !
 

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StreetFighters UNITE
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72 Posts
Discussion Starter · #7 ·
carbs came. but they leak like a crazy, so ill be inspecting them this afternoon.

also i dont have spark, ill be looking into how to do the least amount of wiring in order to start the engine. correct me if im wrong please. i wont need the RR quite yet since its only responsibility is battery charge regulation. engine timing to ECU, ECU to coils, coils to plugs. im left with 2 wires (black white) & (black yellow) coming from the ECU. im not sure what they do but no spark until i find out.


my shop manual in in the mail. but does anyone have a good wire diagram?
 

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Hack in a barn
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4,409 Posts
carbs came. but they leak like a crazy, so ill be inspecting them this afternoon.

also i dont have spark, ill be looking into how to do the least amount of wiring in order to start the engine. correct me if im wrong please. i wont need the RR quite yet since its only responsibility is battery charge regulation. engine timing to ECU, ECU to coils, coils to plugs. im left with 2 wires (black white) & (black yellow) coming from the ECU. im not sure what they do but no spark until i find out.


my shop manual in in the mail. but does anyone have a good wire diagram?
Not only could you blow up a battery but you could also burn up wiring and possibly kill your ecu with out the R/R.... Be safe and hook that up.
 

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StreetFighters UNITE
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72 Posts
Discussion Starter · #10 ·
Not only could you blow up a battery but you could also burn up wiring and possibly kill your ecu with out the R/R.... Be safe and hook that up.
hooooo. thank you mr. for saving the day, i know i would have F'dup all my lurktronics and learned that the hard way.



Looks like you have a Triumph Daytona or Speed Triple shock on there fitted upside down
i suppose that makes it a pretty nice part. it bums me out that it mashes against the swinger.. it also only utilizes the last inch of it travel. gerr PO must have been semi retarded.
 

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StreetFighters UNITE
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Discussion Starter · #11 ·
so id like to share my resources with anyone it my concern. the picture isn't the best so if you have any questions about the wiring on this particular bike feel free to PM me.


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still cant really tell what the black white wire does.. stupid junction box is supposed to simplify things i assume. on my CB its the kill switch.

Ive done a bit of research with little results and come to the conclusion that the RR on this bike is built right into the alternator. in the schematic its a banana shaped thingy that changes the color of one wire passing through it.

cabs should be sealed up good thanks to RTV. 135 main jets in em


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making progress feels great! should be running soon.


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StreetFighters UNITE
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Discussion Starter · #12 ·
she runs! loud and rich. the 2 mystery wires are ignition, safety, and kill switches. turns out the PO had everything but the engine timing wired wrong. power to the coils and ECU i acquired through the red wire connecting the two. used a diode and a fuse for safeties sake.


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the radiator leaks under pressure and i still have the worst of the electronics to figure out.
 

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StreetFighters UNITE
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Discussion Starter · #13 ·

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well my luck turned on me. the fresh oil turned into this ^^^ after about 30 minutes of running / carburetor fiddling. i know its bad but im not sure to what degree. the coolant is appears to be oil free. and the oil pressure is normal. i was sure right off the bat the head gasket was bad but i didnt notice any white in the exhaust.. the coffee color of the oil is the only tell tail sign.
 

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StreetFighters UNITE
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Discussion Starter · #14 ·
so its time to crack this puppy open n see what I'm working with. enjoy.


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cams look good. accept for some minor rust spots, valve clearance is a bit tight, ill adjust upon reassembly.


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i wasn't jerking off. that came out of the engine..


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cams are real easy to pull in this motor. iv noticed the Kawasaki engine is easier to work on than my same year Honda engine.


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head looks good. # 4 exhaust valves sit a little deeper than the rest. clearance adjustment should account for that, not sure if i should be concerned.


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head gasket is good. :hairpull: should have known there are no oil passages in it. would have ruled that one out on the spot. whatever.. checked it.. new one cant hurt.


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cleaned of carbon deposits n turned over the crank. all jugs look good, no cracks for coolant to leak through.


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cleaned up the head. no more gunk or build-up.


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Next suspect is the coolant pump. Driven by the oil pump, but mounted externally.
looks good... I read somewhere online that the seals could go bad but it looks fine. It even has a drain hole where coolant would leak out after the first seal making it impossible to go unnoticed


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I'm out of ideas... why the hell is my oil contaminated?
Maybe just needed to be flushed out good. Anyways ill be thinking on it for a bit before i reassemble and try again.
 

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Fancy a brew?
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Sunken valve syndrome is not unusual on these bikes I have seen it a couple of times on the Gpz zone. Once they start sinking they don't stop, you may want to get them sorted out.
 

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StreetFighters UNITE
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72 Posts
Discussion Starter · #16 ·
Sunken valve syndrome is not unusual on these bikes I have seen it a couple of times on the Gpz zone. Once they start sinking they don't stop, you may want to get them sorted out.
thanks for the pointer. ill definitely keep that in mind.

so with the engine all back together back in the frame and back running, (without coolant) it takes about 30 to 45 seconds to turn the clean oil opaque. as observed through the oil window.

so im gona order a new oil pan gasket and open her up from the bottom.. maybe ill find some fossils who knows. then proceed to flush the oil system multiple times.
 

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StreetFighters UNITE
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Discussion Starter · #17 ·
after stalling on the project for a while i finally got re inspired by some other GPZ builds on CF.

probably should have checked the oil pan first.. this is the filthiest sump Iv ever seen.


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gross! i think Iv discovered the gremlin. and in the mean time i cam across a freebe Ducati muffler at work. i really like the under-tail exhaust on the CBRs, so ill be working on mocing it up.


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StreetFighters UNITE
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Discussion Starter · #18 ·
sus linkage working.


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new foot pegs still need controls


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just some junk for the tank right now, got a Yamaha FZ-09 tank to mess with in the mail.


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still wont run right. lots of stupid emission control vacuum hoses, air:fuel isn't right.
choke behaves like throttle should and throttle bogs and kills it.
 
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