The Green 810

Hi, everybody. I've been a member here for about five years I think, but I've only posted a handful of small things. Since I failed to make a project thread when I first built my bike I thought I should make one about the changes going forward.

The overall bike is pretty much done, it's a completed 79 KZ650B. The future plans are to make it an 810, and do some transmission work while the engine's apart.

I cleaned, polished, and waxed it when it was nice on Sunday, and took some pictures. I'm going through the pictures tonight, which was the inspiration for the thread, so here they are to get it started:









In that last one comparing to the stock bike to mine currently, the stock picture is pretty much exactly how mine looked when I found it in the back room of the shop I worked at. Except it was covered in rust, dents, dust, and dirt. I think that was fall 2004, my senior year in high school. I did a quick and sloppy job cleaning the carbs, bondo-ing the tank, and gave the tank and plastics a silver spray paint job.

It wasn't pretty, but it was rideable. Besides dirt bikes, I think that might have been the first time I'd ridden a motorized two wheeler. The first time I took it out, I promptly found a sharp gravelly turn, slid off the road, and high sided it when I hit the grass. I wasn't seriously hurt, but my bondo and spray was ruined.

After that, I rode it for about two weeks until the carburetors had sucked enough rust out of the tank to pretty much stop running. It was getting cold out anyway, so I decided it was time to tear it apart and do a real rebuild.

I stripped it completely, and took the engine down to the base gasket, and rebuilt it from there. The main changes from stock are a Dyna-S, pod filters, a Vance & Hines 4-into-1, a custom front end, a GPZ 18" front wheel, and a later KZ 16" rear wheel. Those wheels allow me to use the brake calipers and rotors from the mid eighties Kawis (when they switched to square brake pads), which look period correct but are much lighter and work really well. All the other parts are a mix of new aftermarket, and restored ebay stuff. The engine carbs, frame, and plastics are pretty much the only thing original left on the bike.

Tearing it apart only took days, but rebuilding was an extremely long process. Between cleaning, restoring, assembling, fabricating, researching, making decisions, finding parts, changing decisions, finding different parts, and so on, it took about six years. Four years of college got in the way too, but it took thousands of hours.

Finally in the spring of 2010, it was on the road. It looked pretty much as pictured, except for the front end. In order to use the front wheel, which is from a GPZ 550, I had simply used the forks as well. They were air forks, they had a forward axle, and they made the front end longer. After that riding season I was tired of all of those things.

Over the winter, I went back to stock fork uppers, and had them machined to fit the lowers from a GPZ 900. A few things around the axle needed machining as well. This allowed me to retain the wheel and brakes, but returned the front end to about stock geometry. The forks might be a little shorter than stock (which I like), and the front wheel being an 18" instead of a 19" definitely drops it a little more. Combining this with the lighter brakes (reduced unsprung weight, and lighter rotors reduces the gyroscopic effect to lighten turning), a fork brace, progressive springs, and fairly wide Pirelli Sport Demons (110 in the front, 130 in the back), makes for pretty good handling. A lot of people like a larger rear wheel, but the taller sidewall of a wider tire makes up a lot of height. It seems to me that a 16" wheel and a 130 tire have a pretty similar overall height as a 19" wheel with a thinner tire. It might not be quite as high, but it matches my 18" front pretty closely.

Anyhow, no big changes since then. Just oil changes and other little maintenance items.

Right now, there is a 750 cylinder block and head in a box next to the bike, just waiting for time and money to materialize. I have a ton of questions about that, but it's getting late, so I'll save them for tomorrow.

Very nice bike!!

You can tell looking at it, that its a little modified from stock, but it is really true to the original lines and appearance.

If you have any pics from the build along the way, they would certainly be appreciated by many, myself included. I'd be very curious to see what you had to machine to get that front wheel to fit in the stock forks.

Welcome back to KZ.

Jon

A great read and a great looking bike!

Are your engine covers and etc painted or just blasted clean?

I love the flat look that they have.

Great bike and of course it's my color lol keep posting

Sorry for the delay in replying, I saw your posts the day of, but I wanted to find the pictures of the fork mod to show you. Finally located them on an old laptop so here they are.

Jonny, note that the fork aren't stock. Its the stock upper fork tubes machined to fit inside the GPZ900 fork lowers. I used those lowers because they fit correctly with the newer style calipers that match the rotors on the wheel, which is from a GPZ550.



These are the bottoms of the upper fork tubes. The one on top is the GPZ 900, bottom is the KZ 650. Despite looking a little different due to the camera angle, they are exactly the same diameter tubes, so the middle of the 650 uppers will ride in the fork seal of the 900 lowers just fine. The difference is at the bottom; the 650 is the same diameter for about the entire length, whereas the 900 has changes in diameter cut in in a few places.



As you can see, that spacer ring fits over the bottom groove of the 900 upper, increasing the diameter of the assembly to a bit more than the diameter of the rest of the tube. All you have to do to use the 650 upper with the 900 lower is take measurements from the 900 upper and have the 650 upper machined to match it. Making the bottom groove, where the spacer fits, exactly the same is critical, this is what actually slides up and down in the lower. The larger groove and hole just need to be somewhat close, they just seem to be there to allow fork oil to pass through.

I don't have a metal lathe, so I paid my local machinist to do this. I think it was just a little over $100 US. He also has much more accurate measuring tools, I just instructed him what measurements to take and where to cut, and he took care of it for me.



Also, you can see in this photo that the tab on 900 lower didn't meet up well with the speedo drive from the 550 wheel, so I had the machinist weld a little metal on the tab to build it out and then cut it smooth.

Once the forks are together and installed in the triple trees, you may notice that the axle spacer/wheel/speedo drive assembly is too wide to fit in the forks without splaying them out. For this I measured the excess width, divided it by two, and had that amount of material machined off the outside face of both the axle spacer and the speedo drive.

Finally, the calipers may not be centered horizontally over the rotors. Mine were too far in toward the wheel, so I had a bit of material machined off of the face of the caliper brackets where they meet the fork lowers to bring them out a little.

If I still have these measurements I might be able to dig them up for you, but if you get into doing this, it will be best to take your own for your application.

Beezy, the engine covers were bead blasted and then just given a clear coat of auto paint to keep them from oxidizing. I wouldn't recommend this though, the engine heat causes the clear to crack and chip off in some places. I'm going to get them blasted clean again and powder coated.