saving a 1980 KZ750 twin


Oh the usual... I bowl, I drive around...
I originally picked this bike up for a buddy, who vastly underestimated what it would cost to get this thing on the road. The PO did the usual dumb stuff, needless to say it did not run and alot of stuff needed attention. It also has no title. As as started working on it for my friend I fell in love with the looks of this engine, and when he decided it was too much of a financial obligation i bought it off him. Despite the engines external appearance it is squeaky clean inside, and when i checked the valve clearance everything was at optimal spec and it has great compression. I'm starting to think the odometer may be correct and that there is only 4500 miles on the motor. this is what i bought it as...





I know what some of you may be thinking, "Finish your damn kz1000 project first!". I am moving to california in a couple months and apparently registering a no title bike there is a nightmare, its not easy in Washington, however its pretty straight forward. So the plan is to fix what needs fixing, triage some of the stuff i want to do so I don't have to do it twice, get it inspected by the state patrol, and register it before I move so I can start the 3 year probationary period for the title.

Im getting pretty close to being ready for the inspection. I plan to use a lot of the parts that i originally intended to use on my kz1000 before that went a completely different direction. I'm gonna be doing it in a style that has been done to death; aka Go Takamine, Wrenchmonkess.... etc, i think it suits big twins well, and do some small performance mods. Also i want to do some of the stuff guys are doing on their kz1000's like bracing the frame and beefed up motor mounts. Down the road I'd like to send my cams out to megacycle for a regrind, do a port and polish, and get some hot carbs.

Parts i already have slated for use are:
New engine covers - the early twin style, the PO trashed the existing with a flap wheel.
KZ650 spoked wheels - lighter than the stock mags, rear bored out to take 20mm axle.
Avon Roadriders - in the factory sizes, 3.25x18 and 4.00x18
Aluminum Works shocks - these are setup for a kz1000 so likely will need to be revalved/ different springs, they are rebuildable
GS1100E swingarm - shortened to the stock 750 length
tarrozi fork brace
kz1000 forks - rebuilt with progressive springs
KZ1000 LTD fender

I got a chinese TIG welder a couple months ago and have been welding like its a part time job to practice up. Turns out my buddy is not only a great welder he's an excellent teacher, so I have picked it up pretty quick. I'm proud to say I have done all the fabrication on this bike, except the aluminum work on the swing-arm, don't have much practice with aluminum yet.

Ill let the pics do the talking from here


















Looks like a good project - after seeing your work on the KZ1000, definitely looking forward to following your progress.
Ill get some better photos of this when its done. still needs shock mounts, torque link mount, chain rub, chain guard mount, and a zerk on the pivot tube. (where were you on that Suzuki?)




I have been reading up on artificial aging with aluminum to return strength. For a precipitation heat treatment of 6061 you do 6-20 hours at 320F°. Or 6-10 hours at 350F° I know the stock gusset in between the arms is a different alloy because it reacted very differently to the NaOH. it stayed bright while the arms turned dark like 6061 does. Some alloys aren't heat treatable, so it may not make a difference for that but i figure its better than nothin. My neighbor is a chef and has a commercial oven in her house that she has agreed to let me use to bake this thing. Im going to use a rockwell gauge to see how hard it is before and after, mostly for my own curiosity.
Adventures in aluminum... other than some practice beads, this is the first aluminum piece i have ever fabricated/welded myself. I am loving this welder.







Seat is coming along. The top is finished and i have the sides basted on before doing th real seam. I dont really like making seat covers, they stress me out.



I revised the mounts on the taillight and it is finished. i probably will paint it black, lol.







Well Howdy Dudy Mang! Nice work on the TIG time, been working with my Chia TIG also, once you have the setups dialed for materials and sharpen a dozen electrodes for those blind oop welds it's so much cleaner than the hot glue gun... dab don't poke!

Not a fan of the two hole Kowi but I'm sure it will pull it's weight :eek: Sweet light bracket remake.
Thanks Tune. I don't know how I will like the bike, Never ridden the 750 twin before, so like a dumbass i'm going to put a lot of time and money into something I may dislike. I do love the looks of the engine though, particularly the clutch cover.

On an awesome note, State Patrol contacted me yesterday telling me they had an opening in the schedule today if i would like to come in early for an inspection. Called in sick to work, then cobbled some shit together making sure all the lights and brake worked, and passed the inspection. 8) The officer didn't even look at the bike she was just interested in the VINs, so i probably didn't need to stay up till 5 am troubleshooting the lighting system. Now i can register it and start the 3 year probation period for the title. Stoked!


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Damn Doc, you are knocking this outa the park. I love the kz twins. I have an 81' I'm rebuilding slowly. Your tail light rocks. Nice skills.
Thanks man. The kz750 twin is a strange beast. definitely the black sheep of the kawi lineup of the time.

did the first pass on the side panel today but I'm almost out of thread . Im sweatin doing the final fold seam where the quilted part meets the side, that seam is over 4 ft long.


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Heck yeah. Killer work all around. What kind of machine are you using? Standard or an industrial with a walking foot? They can be a struggle, and getting through a big seam like that on one needle is close. They usually want to pop pop pop about 3/4 in. I'm still trying to figure some of that out.
Thanks, I'm using an old Husqvarna machine that my mother bought in 1975. Im actually quite impressed by how well this machine handles multiple layers of foam and vinyl. I have been thinking about splitting the seam into two passes and sewing a small piece of cording in the back to cover where they join.

Tonight I finally mounted the courage to attempt the fold seam, had a couple beers and went for it. It came out pretty good, not as nice as i would have hoped but i'm cool with it. I ended up splitting the seam into two chunks, and undid the rear seam to insert some webbing to cover up where the two sides meet. I cut the excess out of the cover and stretched it on the pan with tape so i can make sure that my pattern for the boxing section at the front is still good. In the pic of the webbing on the back you can see some small holes where i removed a seam, i thought i sewed inside those but guess i didn't. i have some vinyl repair stuff that will make them virtually undetectable. ::) I don't want to ever make another seat, they stress me out too much, some things are better left to the pros.


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Wow bud, you are doing some really nice work and turning out some really neat stuff here.
Looks great so far been trying for the last couple of years to pick up 750 twin but not much where live.
Thanks guys. I had never seen a 750 twin in person prior to this, kinda rare.
My wife is gonna attempt the seat cover for her CL100. Upholstery leather. What brand/type thread are you using?

BTW the seat you are making is mind blowing.
thank you. Not sure of the brand but i'm using a 92 weight polyester thread. its super strong.

this is exactly what im using, except i get it locally for 1/3rd the price, so I'd shop around
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