And so it begins... 1976 KZ750B Twin barn find project.

If you want to minimize your upfront investment until you first know it runs, I would first get spark at the sparkplugs. Then I would use an auxiliary tank. Can use one from an old lawn mower or weedwacker . You can can use a fuel shutoff valve from one of these as well. Then you can focus on getting it started before worrying about cleaning the tank and investing on the petcock. That is what I did. I wanted to make sure there was nothing internally that keeps it from running. You can even get it started with out gasoline by spraying starting fluid into the carbs. Open the throttle and shoot about 3 or for shots of starting fluid in each carb. It should run for a few seconds. You can even do this without the carbs installed. Never tried it that way, but my nephew did on CB900 he was trying out. Once yo hear that engine roar, you will know where to go from there.

MEK and a handfull of sheetmetal screws will clean out the tank. I removed a liner from a tank that wsy and found the tank to be in great condition.

Agree on using MEK to remove the old liner. It won't derust though. For that I like to use phosphoric acid. Kleen Strip Etch and Prep is commonly sold and will eat the rust out of the tank in a few hours. Recycle for future usage since it can be used again and again.

I used Acetone to remove a degraded liner out of my 1000 B2 tank. MEK is nasty stuff. My cousin worked for a paint making company and said stay away from it. Then the crazy fool would put his bowling ball on the porch and douse it down with MEK and light it on fire. He claimed it would draw out all the old Lane Oil and make his ball work better. Consider the source

If you use a phosphoric acid solution (it works great, btw) make sure to allow the tank to vent while soaking. It will outgas, so if the tank is sealed while doing this it will build up pressure and your tank will expand. Ask me how I know... :whistle:

I used Metal Rescue on mine and it did a fantastic job. Actually, I used it to derust every metal parts, screws, rear springs, chain, etc. And it is environment friendly as well.

Have you checked Classic Octane YouTube Channel? He has restored a similar bike.



JL

DoctoRot wrote: I totally get just trying to make it run but FYI the stock ignition system on the 750 B is pretty lazy. if you can find the electronic ignition setup from a late model 750 twin or a 440 twin the bike will be way happier with more timing and more advance.

Thanks for this advice. I was hoping to find a suitable electronic ignition if this thing runs half-way normal after some replacement stock parts. I wondered if later model 440 twin igninitions would work.

Good afternoon motorcycle fans,

I appreciate all the advice on tank clean-out. Lot's of great suggestions. I'll be honest, I was super curious about the cleaning grade vinegar. I can't believe I've been working on old stuff for this long, and hadn't heard of this technique. So I wanted to try it and I did!

I removed the fuel petcock and plugged it with a rubber expansion plug. Then I put the tank in a plastic tote to contain any leaks. I tossed exactly 30 sharp and pointy construction screws in there for agitation. I filled the tank to the lip of the cap, and let it sit under the workbench for a couple days.



After the weekend, I pulled the tank out, strained off a couple gallons of vinegar in to an oil pan, closed the cap, and shock the crap out of it for about 10 minutes. Then I strained off the rest of the vinegar to inspect the tank. I forgot to take pics of the inside of the tank, but there was a lot of clean bare metal with a bunch of flaky liner bits laying around in there. This tank is really solid, no leaks, no obvious soft spots or excessive rust damage. So I decided the vinegar was doing it's thing. I re-filled the tank with the same strained vinegar, topped it off, closed the cap, and back in the tote and under the bench it sits. Below are the contents of the strainer, and one large chunk of old tank liner I pulled out of there.





I'm pretty confident in the vinegar at this point, I'm curious to see the end result. I used the same vinegar on the chain I'll share in a later post.

While the tank is being pickled, I decided to move forward and tear things down a little more this weekend.





Pulled lighting, controls, carbs, air box, and brake assemblies. I'll soon be wrestling with each I suppose. I left wiring and electronics in tact in order to get at least the skeleton of this thing to run...

It's the little accomplishments, right?

I got the ignition parts swapped out. Had to come up with replace points and condenser machine screws, but that wasn't so hard. Here's pics. Hooray me!

Nice work! Can't wait to see the final product.

One more shout out to vinegar, color me impressed.

Amongst other things, I pulled the chain from bike. Below the first picture is right after I set the greasy and crusty chain in a shallow bath of the same vinegar I used in the tank.



I filled the pan enough to submerge the chain, and let it sit overnight. After a 24hr soak, some random flipping and scrubbing with a toothbrush sized wire brush, this is what you have.



Even in this condition, there were still a couple stiff links. So back in the bath it goes. It's napping there now and will be until tomorrow. I'll take some pics of the final product. I know chains are relatively cheap, and nice new o-ring chains are nice, but why toss it if I don't have to? The bike is low miles for it's age, the chain shows little wear or any damage from age, if I can clean it up and re-lubricate it, I see no reason not to use it. I'll keep an eye on it. The bike is far from a performance machine by today's standards, and I don't plan on excessively beating on it.