1981 KZ1000 J-to-K build

Nice work!

Today kids, we discover the smell of gasoline that has been sitting in carburetors for around 12 years! :sick:

Its been awhile, but I've finally started moving forward again. Thanks to another member I now have a pair of side covers and even scored a meter bracket! I believe I now have all of the components to put the bike back together the way it was intended, and at some point start deciding on any customizations I want to make. I also managed to clean off a section of my workbench so I have a place to start working on the engine. One of the engines had the head loose, so I had the whole thing on the workbench to pop the carbs off. When I got them loose and flipped them over, something resembling very old gas ran out on the workbench. Now the bike this engine came from hasn't been licensed since 2001, and I've seen no reason to believe the engine hasn't been run in all that time.

I've seen a lot is discussing about different carb sizes... 27, 28, 29mm. Could someone please clue me in as to what exactly is being measured? One set of carbs came from an '81 J, and I believe the other set is from an '81 K. So is one set going to be better than the other? Other than the gasoline sitting in the bowls, it appears that both sets are in fairly similar condition. There is one thing that stands out though... In the first picture below (J), note that the bowl drains are facing towards each other, while on the second picture (K) the screws are facing towards the outside of the engine. Does this indicate any substantial difference between the carbs, other than the set from the K engine will be substantially easier to reach those screws?





I took a wire brush and a putty knife to the frame and some other parts, got things cleaned up fairly nicely. I think the frame is ready to go in for paint, except I'm thinking of bringing the tips of the exhaust pipes up a few inches (I like the angled look better) and I need to determine how I will hang the pipes. If I need to weld a new bracket to the frame, I obviously want to do that before having the frame powder-coated. Once I start getting these engines pulled apart, I'll probably have to set the empty shell back on the bike so I can mount the exhaust pipes and the aluminum foot peg brackets, and see what I have to work with.

I should probably start selling off the parts I know I won't need. I have the gas tank with some small dings, and some side covers that may have some off an earlier model. One of these days I'll start sorting through everything just to get it out of my way.

Just swap the end bowls and they will be correct.

Oh of course!!! Why didn't I see that?

to find carb size you need to measure the i.d on the side of the carbs that fit into the intake boots.

leon

Shdwdrgn carbs just as Leon states and you will find the J and upover series stock carburetors to be 34mm. They are the same so only overall condition will decide which is the better

Ah ok... As you said, both of the carbs measure at just under 34mm. Guess I'll just start with the one that is cleaner and swap the bowls around. Thanks for all the info!

The closer I look at the bits and pieces that I have, the more I realize that I can't take shortcuts anywhere... I have to do a full tear-down and inspect everything... I started tearing into one of the carbs today. It appears that someone else has already been in here. The floats appear pretty new, and the diaphrams are in good shape, but what really stands out is the screws that was the wrong length, and the handful of screws that are completely missing. Its a good thing I have an Ace hardware a block away with an excellent selection of metric bolts.

Since I plan on painting the carbs, I really need to do a full tear-down to get everything cleaned and painted completely. I just never expected I would also be cleaning up someone else's mess. I'll be swapping out some parts from the other set of carbs as well. The throttle cable bracket and one of the choke brackets are bent -- hopefully that was all. I also noticed it appears that the outside float bowls and the top cover were chromed or highly polished, but the inside carbs just look like plain aluminum. Ah well, its all getting covered up.

Painting would be easier if I could take out the butterflies, but my experience has been that the two screws holding the butterfly plates to the throttle shaft are generally pinged to prevent unscrewing, so I'm not going to mess with these. I did get the pieces off the shafts that hold the springs, so the claned springs should make a nice contrast against the flat-black bodies when I'm done.

Before I took everything apart, I also noticed that in the closed position, one of the butterflies was showing light around it. Obviously not in sync. I need to start reading the forum for info on adjusting the floats, and anything else that should be checked while I have these apart. Nearly time to get that soda blaster so I can start cleaning the pieces, but its still going to be a few months before I can start painting.

So it turns out there IS a difference between the carbs. Looking through my Clymer today, and verified on the actual carbs, the J models have a coasting richener which adds fuel while decelerating. The J and K also have a different set of needles/jets (127.5 and 49 on the J, 122.5 and 51 on the K). I find it interesting that the J, which is the base-level model, has the extra feature of the coasting richener. Why don't other models have this? They all have the same engine, so why is it only needed here? And why the difference in jet sizes?

Anyone familiar with carbs, please explain this to me. Also, any suggestions on what combination might be best for me? My typical riding is a mix of highway and city. I rarely get out on the interstate, but I do ride in the mountains when I can. I have no problems gutting both carbs for a set of parts that works for my riding style.

Got a chance to throw together some engine parts on the frame today and take a look at how the exhaust lines up. I think I want to put a slight upward bend in the end of the header section and bring the tip up at the same angle as the bottom of the aluminum side plates. It looks like I'll have to wait until the rear wheel has been assembled again, to confirm my clearances. Hanger brackets should be easy enough to punch out and put the pipe right where I want it though.

The good news is there's no reason to think I need to add any special hangers directly to the frame, so I can start getting parts powder-coated as the money comes available. I just need to start checking local shops and find out how hard the powder-coating is gonna hurt my wallet...

a lil closer :evil: !

keep us posted,

leon

At this rate I should be done in about 10 years! :laugh:

Last week I took my wheels over to the Kaw dealer and had the tires removed. Both wheels were slimed (I assume something to repair leaks?), so I had to do a bit of work with a hose and wire brush to finish cleaning them up. The dealer informed me that the bearings in both wheels were completely shot. Good thing to know before I get it on the road! So I just need to get the old bearings tapped out and the wheels will be ready for powdercoat.

Yesterday I finally got around to working on the carbs again. I made up a coffee can to drain gas into each carb so I could check the float levels. Two of them needed adjusting, and I had to remove one of the bowls from the spare set of carbs because the drain screw was seized and the slot in the head was stripped out. It seemed to go pretty well though, and I have the bowls and the top pieces screwed back on in prep for soda blasting. I need to find some pieces of foam to fill some of the holes so I can limit how much soda gets into places it shouldn't.

The little sandblaster arrived last week, and I have a cheap 30-gallon tote I'll be prepping to use as a blast cabinet. The medium-grit soda should be arriving this week, so hopefully I'll get the carbs blasted soon and then they'll be the first pieces I paint. I'm considering leaving the screw-heads in bare steel to contrast against the flat-black of the engine, give it a bit of an industrial look, plus paint tends to flake off any screws if you ever have to remove them.