New Member and Carburetors

I am new to this forum and want to extend a personal Thank You to an Administrator named "Patton" for his many postings on how to properly adjust Z1 carburetors. I purchased my 1975 Z1b, March 17, 1975 and today it has 24,800 miles on it. I still have that bike, the warranty cards, a complete, original, tool kit, the Owner's Manual, Owners Warranty Manual and the July, 1974 Kawasaki Shop Manual, Z Series but with the 1975 Supplement at the back of the manual. The bike is all original except for the front tire which had dry rotted so bad that even though it still held air it had to be replaced. The back tire is still the original tire, still holds air properly but has a lot of side wall cracking so it's time for replacement. The mufflers are original Kawasaki mufflers with the Kawasaki name and serial number on each one. Earlier this week I thought they were prefect but discovered a crack on one of the mufflers near the junction for the exhaust pipe so it looks like these may be replaced too. Fortunately, i have a brand new set of four mufflers, never used, that I purchased in 1976 from the Kawasaki dealer to use as spares if ever needed. They are the ribbed mufflers, have Kawasaki Z1, Z2 serial numbers and the clamp I read about. Always garaged, in deciding to start riding it again I needed to clean it up and do some motor tuning. The brakes are perfect, as is the clutch but once it was started it would not idle below 2000-2500 rpm unless the choke was half on. Throttle response was terrible and if I moved the Choke lever anywhere near off the motor instantly died regardless of throttle position. Some parts of the Shop Manual were confusing in the described procedures. Mr. Patton and this forum have been a huge blessing in allowing me to figure out what I needed to know. From Mr. Patton's postings I learned how to properly bench sync the carburetors and from other postings, that the Pilot Jets needed to be cleaned out to resolve the idle problem. All four were blocked solid. They have a .0175 orifice in their center so I used a 2 inch long piece of smooth wire I cut from a cleaning brush that was exactly .014" in diameter, a lot of carburetor solvent and very carefully cleaned them out. A red nozzle extender, like a straw, from a WD40 can with one end sanded down a little to fit into the end of the Pilot Jet, with the other end plugged into the carb cleaner aerosol can allowed me to blow carb solvent through the jet. When the solvent was a solid stream I knew the jet was clean. Next, I weighed the floats on a gram scale and they varied from 9.8 to 9.9 grams. A brand new, unused, old stock float, still in the Kawasaki wrapper, was 9.9 grams. The floats looked good so I reset all float levels, then adjusted all four slides using .026",gauge wire .028" gauge wire and .30, gauge wire accurate to .0005" I bought from a machinist supply business. Only $7.50 for all three. It was tedious but now the .028: wire will pass through each slides small slot on the engine side of the slides, but not the .030" wire. That slot is so small it was hard to see. It is at the bottom the slide, in the exact center on the engine side of the carbs. I also checked each carb's needle and seat and main jet. Before I started the bike, or even turned the engine over, I sprayed oil into the spark plug holes using a curved nozzle and turning it all around each cylinder, then gently rocked the crank using the large nut under the points cover. After that I used the kick starter by hand to rotate the crank a few times then fired her up and I was amazed. She runs like new, idles perfectly, revs up shockingly fast and does not smoke. VERY happy! A short ride proved the clutch was still smooth, the transmission shifts perfectly and the engine was smooth. I am thinking I should replace the original rear tire and now it looks like I may have to replace what I thought were perfect mufflers, after finding that crack on the left, upper, muffler. This forum has been an invaluable source of technical information and I truly appreciate being able to access it. Looking forward to learning more as I go along. A few photos are attached. My first trip on this bike was in August, 1975. I was teaching then and had the summers off. Rode 8000 miles in 30 days, all over the USA, with no windshield. Camped out. No motels. Best solo trip I have ever had.

That is a great looking bike. Not many unrestored in that good condition.
Jerry

Still working on cleaning the bike. It has never been restored or reconditioned and is still all original except for the front tire and the battery. Thinking of going to a gel battery to eliminate that vent hose. Fumes from the former vent tubing ate all the paint off the center stand and part of the swing arm. No damage and they've been repainted. A longer vent tube has been installed and routed to the back of the bike so the fumes don't touch anything as they exit the battery. Flushed out the sticking front brake system and replaced all the old fluid and the brake now works perfectly. Still has the original pads. Reset the points gaps and using an ohmmeter, reset the dwell. Also oiled the little felt lubricating pad. One valve was at .0015 and I found a brand new shim on eBay that brought it up to .003". The rear brake is still all original but needed nothing. The fuel tank has no internal rust but the petcock was gummed up with a lot of dark brown tar like substance from old gas. It dissolved in Lacquer Thinner and I very carefully cleaned it up while trying to not damage those little filters. The valve is hard to turn but does not leak. Finally was able to take the wife for a 20 mile ride Thursday afternoon and it was a good time. Looking for a new Dunlop rear tire, the same as the old 1975 tire still on the bike. It holds air with no problems but is starting to show some mild side wall cracking here and there. The bike runs really well now but I think I need to use a real dwell meter on the timing and a mercury manometer to fine tune carb synchronization. Continuing to clean and polish everything. Some of the original cover screws looked like they were corroded or rusted but cleaned up well with some rubbing compound and a small buffing wheel. The chrome on all but one or two if those Phillips screws actually looks pretty good. The two on the chain guard did not clean up so well and might have to be replaced. Love this bike. I think it's one of the most beautiful motorcycles ever made.

The stock tires were junk. A good set will make it handle a lot better. They were the first things I changed when I bought mine new.
Steve

I would install new tires with good wet traction, especially since you're taking along a passenger.

The Morgan Carbtune seems to get good reviews in the various forums.

That is a nice looking bike!

Thank you everyone for the very kind comments and helpful suggestions. This is a great forum and it is good to see so many still enjoying these old Z1's. I am having a great time with this bike, all over again.

Many years ago I embarked on an 8000 mile 30 day trip all over the USA. No windshield or fairing. Just me, a backpack and the bike. When I returned home my butt was so numb from the many long hours on that original, stock, seat it was six months before normal feeling returned. One experience was riding across the Continental Divide at 12,000 feet above sea level. The Kawasaki dealer told me it would not run at that altitude without re-jetting and tuning it for high altitude. Baloney. It ran, and it ran really well without touching anything, even up long grades. I was headed for California and once over the top, on the downhill west side I coasted for 12 miles, engine off, before I had to do a restart.

Work is progressing and I learned something unexpected. i was having a bit of frustration polishing engine covers and the original phillips head screws. Not to a mirror polish but just to a nice satin finish like it was when I first bought it way back in March, 1975. I tried the new Dupont #7 white Rubbing Compound, the Dupont #7 white Polishing Compound, Turtle Wax Chrome Polish, some of the Mother's products and a few others. None of them were really very good. Then one day a week or so ago, I was cleaning out a cabinet and found a really old, green and white 12 ounce can, partially filled with that old time Dupont #7 Rubbing Compound that is a sort of a reddish pink color and smells like it has ammonia in it. I tried that just for fun of it using a 3" diameter polishing wheel in a Snap-On die grinder. I wet the wheel, spun it to get rid of the excess water and wiped some of that compound on the surface I was polishing, not on the wheel itself. Running at about 500-1000 rpm, that stuff was amazing. It really worked, and worked so well it made all the newer products look almost defective. Plus, no scratches or blemishes. Noting was corroded, just tarnished, and it cleaned that aluminum right up. Unfortunately it is no longer available but what I had really did the job so now I am looking at garage sales, etc., to see if another can might turn up.

I have discovered a UK source that is selling brand new Dunlop Gold Seal K87, 400/18, H rated tires and also the Dunlop K70, 325/19, H rated tires that were original to the bike. I have learned from the experiences of much better riders than I, that there are better tire choices but I kind of like the idea of keeping the bike as original as possible. Now, if I can just find $500.00 to cover the tires and the shipping the bike will be all original again, so to speak. No idea why Dunlop still sells the K70 but has discontinued the K87.

Be aware - the are no Phillips screws on the Kawasaki. Despite their appearance they are not Phillips screws. They are Japanese Industrial Standard (JIS) screws. The tips of Phillips screwdrivers are too long & pointed to allow the 4 blades of the screwdriver to properly engage the screws, so when you apply force the screw head slots will deform and look like crap. The fact is that Phillips screws were deliberately designed to have the screwdriver bit "cam out." This was done to prevent production line assembly from over-tightening, stripping, or breaking the screws. JIS screws do not have this problem. A proper fitting JIS bit can tighten a JIS screw to and beyond the torque spec without camming out. Here's the good news - you can easily modify standard Phillips screwdriver tips to fit the JIS screws.

I have ground down the tips of DeWalt #2 and DeWalt #3 Phillips to make them fit JIS screws. The large crosshead screws on the cases take modified #3 bits (or genuine #3 JIS bits). To modify the DeWalt bits you need to grind the very tip a little, then test fit, then grind a little more and test fit, etc. until the bit no longer "rocks" back and forth in the screwhead. Picture 1 below shows how a DeWalt #3 bit fits the case screws of my KZ650 after being ground properly. The #2 DeWalt bits can be modified the same way to fit smaller JIS screws. Pictures 2 and 3 below shows DeWalt #2 and #3 modified bits.

I did find a place that sells authentic JIS bits. They don't list the #3 bit, but if you contact them they can provide the #3 JIS bits even though they are not listed on the website. These folks were very easy to work with, and the authentic bits do work great. Here's their site:

www.rjrcooltools.com/shop_item_detail.cfm?subcat_ID=89

Pictures 4 & 5 below show a comparison between my home made modified bits with the authentic JIS bits. Picture 6 shows the differences in the tips' angles. Ed

PICTURE 1

PICTURE 2

PICTURE 3

PICTURE 4

PICTURE 5

PICTURE 6

650ed, This is great advice! I have seen reference to JIS screws on other sites and from vendors that sell Kawasaki Z1 parts but never knew what the difference was. I copied your notes and photos and have them in my 1975 Kawasaki Z1 Service Manual

I was lucky to find a Dewalt bit that fit perfectly and used it with my hand held impact tool that you strike with a hammer. This is the only way I was able to loosen all the screws without deforming them but I do have several that have been deformed from past years of removing them for one reason or another. Now I finally know why it was so hard to find a tool that fit those screws properly. Thank you for sharing. I have not yet replaced the deformed screws because they still work but I am thinking of replacing them if the replacement screws are exactly OEM. Maybe even from a salvaged Z1.

I've owned my '77 KZ650-C1 since new, and I wrecked more than a couple screws before learning they were JIS. I replaced the ones I damaged with new old stock screws and have never had any more problems after I stopped using Phillips bits. Another thing I learned was to use Kroil penetrating oil to break the bond on fasteners that have not been removed in decades. If you are not familiar with it let me know and I'll provide more info. An engineer friend told me about it and I was amazed at how well it works. Ed