Saving an '84 KZ700 from a garage

Hi everyone!

New member here -- just posted in the New Member forum too, but this seemed like a better board to tell the story of how I got my KZ700 running. I started riding about a year ago on an '83 Honda CB750 Nighthawk, and bought my way into your club back in April when this little sweetie appeared on Craigslist for $400:



45 minutes after he posted it online, I had the signed title in hand. The Nighthawk was a little jealous.

Things I knew before I bought her: She hadn’t driven in 10 years, and hadn’t run in 5, so she needed a new battery, new tires, and a carb clean. The front left blinker had been smashed on the wall of the PO’s garage. The rear brake fluid reservoir was empty and the pedal went to the floor without doing squat. The shifter pedal was extremely sticky and wouldn’t return to center after pressing it up or down. The clutch lever was really hard to pull… and I mean REALLY hard, not “sporty feel” hard, though that’s what the PO tried to tell me it was. The throttle took ages to return closed after opening it.





All the work I’d done on my Honda to get it running (and then keep it running) and the one sentence I read online about it being basically the same bike as the KZ750’s that year gave me confidence. After all, she was only 6500 miles old. So I put her on a trailer, got her home, and pushed her to the back of the driveway I share with 3 other apartments (sorry guys), where she would sit for the next 1.5 months.



While the new battery was on its way, I changed the oil, then started investigating the shifting problem. The shift lever was stuck fast on the pivot rod. Pulling it off took a lot of patience and muscle, but once it was cleaned, lightly lubed, and reinstalled, the lever worked like a dream.



Now for the clutch problem. I had bought a new cable thinking that was the likely culprit. To install it I had to remove the sprocket cover plate, where I found this unholy mess:



Whatever awful substance was used on the chain had turned solid and infected everything inside that cover. By the time I was finished in there, it looked practically new:



I lubed the moving parts and reinstalled the cover, and the clutch felt beautiful. On to the next thing.

I went to pull the carbs and found the air intake under the seat. I figured I ought to check out the state of the air filter, so I unscrewed the cap:



I don’t even know what to think about this one. Perhaps some large insect dissected the filter to make a bed for its nasty babies? Whatever was in there, I sucked it out with a shop vac and finished it off with a paper towel. Yuck. New filter ordered.

Now back to the original task. I pulled the carbs, bought carb cleaner -- as always, one can per carb plus another one for good measure – and set to disassemble them. WOWEE were they nasty:





The vacuum pistons were so gross that I had to reach into the throats and push them up and out by hand. The float bowl gaskets self-destructed when I pulled them off, and all four float needles were stuck. It took about 20 minutes of working the throttle butterflies open and closed while spraying the joints to get them to spring back on their own. I stuck all my wires in all the places I could find to stick them. I sprayed every hole those carbs had until it squirted out somewhere else (*cough*). I noticed that they still have the factory sync:



Finally they were clean and right back on the bike (which, by the way, is one heck of a lot easier to do than on my Honda). The new air filter and battery had arrived and all the electricals worked, including the new turn signal. I threw the tank right back on the bike with a full tank of fresh gas and primed for a couple minutes. Full choke and hit the starter. Rrrrr-rrr-rrr-rrr-rrr-rrr-rrr-VROOOOOOM-click. It revved to 4k and immediately died. BUT IT RAN!!! Okay I gotta try this again……… Long story short, I could keep her running around 6k RPM with lots of throttle and full choke, but if I let her drop lower than 4k, she couldn’t come back up and would eventually die. Pilot circuit problem? I dunno.

FINE. I’ll pull the carbs again. And boy am I glad I did before I tried to run that poor engine anymore… throats 1 and 2 were bone dry. The float needles had re-stuck themselves while sitting on the bench waiting for the new float bowl gaskets to arrive. Having done more research about the mysterious internal passageways of the Mikuni BS34’s, I poked and sprayed more holes until I was satisfied they were all clear. Then back on the bike again.

She runs!!! But she and I had to compromise and run at 4k RPM, because if I backed out the throttle screw anymore, she would die. Hmm… Sprayed some leftover carb cleaner at the intake boots, and yep, she screamed up to 7k. Four boots ordered.

While waiting for the boots to arrive, I refilled the rear brake fluid. It has worked great ever since; the fluid hasn’t leaked and the level hasn’t dropped a bit. ¯\_(ツ)_/¯

When I got the notification that the boots had arrived, I left school early (don’t tell my research advisor) to put them on. Start her up and she’s still racing… but now when I adjust the throttle stop screw she settles down, down, down, all the way to 1200 RPM, where she sits happily. I blip the throttle and she says hello and settles right back down.

I felt like a supreme being who has created life.

I got her registered and took her around the block for the first time, grinning from ear to ear. Much smoother throttle response and less vibration than my Honda, even without syncing the carbs. The skinny tires and 50 lb less weight make it that much nimbler around town. The rear disc brake works so much better than the Honda’s drum brake that I accidentally squealed it to a stop in front of some very disgruntled elderly women.

With my next paycheck, I bought new tires. At some point I realized the old tires were original… so I stayed off the highway until the new ones arrived. I slipped them on (HA! It took hours!), polished the rims, waxed the paint, polished the chrome, and stepped back to admire my handiwork:





WHAT A BABE. I am head over heels in love.

Unfortunately, it’s extremely impractical for me to have two bikes in my current living situation, so I sold the Nighthawk. It broke my heart to see her go, since she was my first, but… out with the old, in with the 1 year newer, am I right? Fortunately, I did manage to get the photo in my signature before I sold her (also with my boyfriend’s Triumph TT600 and our shared [nonworking] Honda Shadow).

There are still a few things on my long-term to-do list: touch up a couple holes in the black paint on the tank and sissy bar, polish up the aluminum covers, and sync the carbs (been putting this one off since she already runs so smooth). I should check compression, and probably check valve clearances, though I'm loath to take the cover off because it's oil-tight right now and I don't want to touch it. My Nighthawk had an annoying recurring leak in its cam cover gasket that I had to change out twice in a year.

So that’s it! That’s my story. Thanks for listening, if you made it all the way to the happy ending, and I hope you enjoyed. See you around...

Great job. Looks like new . Looks to be all original. You have a classic bike.
Well done

Nice photo-essay...nice save!...you have a rare motorcycle...only 2000 ever produced.

Nice work! I've owned a bunch of different bikes over the years and the KZ750/4 family of bikes are some of the best.

Keep going on the maintenance. You should consider tearing down the brake systems to remove sludge and replace the brake lines. A valve adjustment should be at the top of the list though. The valves tighten with mileage and eventually all the clearance will be gone and they will burn. I bought a KZ750 engine one time and upon inspection there were chunks of the valve seats missing because of neglected valve maintenance.

You definitely kept the right bike! I'm happy to read that you are using a very methodical approach in restoring the bike. It's looking really nice, and I'm glad to see it's running well. Having such a super low mileage, scarce bike sitting in what basically was an abandoned mode was a shame; kudos to you for the rescue! Ed

Too bad some others don't see the value in keeping a bike unmolested. :whistle:
Steve

Looking at the maintenance chart, you're right... Presuming the valve clearances were adjusted when they should've been at 3000 miles, it's time to check them again. If they weren't checked at 3000 miles, then it's really time.

Hey, do you (or anyone else) know how the timing works on this bike? It looks from the service manual to have an automatic timing advancer, so I wouldn't need to adjust it like on the Nighthawk?

Take a look at the link below as it contains some limited info on the KZ700-A. Notice the ignition timing is mentioned on the page marked 409. It mentions checking the operation, but it doesn't appear to have any adjustments. Ed

www.750turbo.com/manuals/Base%20Manual%2...-%201984%20Model.pdf

That's a beautiful Bike. Pleas keep it original or at least dont do anything that can't be reversed. Your bike is basically a KZ750L3 that's been de-bored. The KZ700A was a blip on the radar to comply with "Harley-Davidson" tariff. They talked they're buddies in Washington to add extra import taxes on any bike over 700 cc. It was reversed soon after so there was no need for the model after.

The tanks on these bikes are very rare in the states so take care of that one.

That figures. So now there are millions of Japanese V twins running around in pay back? :lol:
Steve

Looking great, you got a smoking deal on that bike, you lucky bastard

Sweet find and you are doing a really neat job getting it back to its former glory and I can only fill in the choir pls save that fine find for the afterworld. The world is already full of unloved bobbers. :lol: :lol:
/A