Kawasaki's classic KZ1000, KZ900 and Z1 motorcycles. Keep them running and on the road.

Z1R Magazine Ad

This ad appeared in motorcycle magazines such as Cycle, Motorcyclist, Cycle World and Cycle Guide back in 1978 .

1978 Kawasaki Z1R

KZ1000J magazine advertisement

1981-1982 Kawasaki KZ1000J

Here’s an ad for a 1981 or 1982 KZ1000J.  I believe the red paint job was the same for both years.

Kevin Luckhurst in Practical Sportsbikes Magazine

Kevin Luckhurst and his KZ1000 are featured in the February 2018 issue of Practical Sportsbikes magazine.

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Besides the KZ1000 Kevin also owns a 1975 Kawasaki H2 and a Yamaha RD350LC.

tiki4tara-blog asked: What is the spark plug gap for a 1977 Kawasaki KZ1000 LTD?? Thanks

.028 to .032 inches.

How to fix KZ1000 idling issues

Do you notice how hard it can be to get an older motorcycle to idle smoothly, especially when the engine is cold?  Is your KZ’s idle speed too low when the motor’s cold then after turning up the idle the bike idles too fast when it’s warm?  

My KZ had these problems even after I installed new pistons and rings, removed the valves and changed the seals, cleaned the combustion chambers, new ignition coils and cleaned the carbs.  The intake manifolds are newer, having been replaced in the past couple of years.  What else could it be causing this problem?

There are several things to do and they might not be easy for a novice. Be systematic with these tasks and the probability of success is high!

Here we go:

1. Clean the carburetors. The pilot jet system has small orifices that will clog easily from dirty fuel.  An old gas tank might have rust inside. The rust might get into the carburetors and block the pilot system.

Use this graphic as a guide for cleaning Mikuni carburetors:

kz1000 carb cleaning guide

In the graphic, the airflow goes left to right.  The pilot air passage #2 and the pilot jet #4 tend to get gummed up when a motorcycle sits for months with gas in the carbs.  Ethanol gas is worse than old-fashioned non-ethanol gas. Ethanol gas gums up carbs more quickly than non-ethanol.  Use carb cleaner “liberally” - that is, use as much as you need to get these orifices and jets squeaky clean.  If you don’t then you might be taking the carbs apart again soon.  And the four cylinder carb banks aren’t the easiest to remove from a bike.

2. Check the intake manifolds for leaks.  If the manifolds appear to be as old as the bike, CHANGE THEM!  They might be 30-40 years old and all it takes is a couple of cracks to cause air leaks and they will screw up the engine idle.

3. Air filter(s). If you’re running the original airbox, take a look at the air filter and decide if it needs replacement.  If the filter is a K&N or UNI replacement, it can be cleaned, oiled and reused.  

If the filters are individual pod-type, inspect each to be sure they’re in good shape.  If they are cheapies (not K&N or UNI) take a look at the rubber mounting flange to see that it’s not blocking the pilot air passage (#2 in the graphic above). If the air jet is blocked or obstructed, fine tuning might be impossible. 

4. Valve Clearance. If there is insufficient clearance, the valves will not close completely when they should and fuel mixture leaks through the valves while the piston is compressing the mixture before ignition. It causes poor combustion and performance.

The correct clearance is .05 to .10 millimeters. Here’s a helpful graphic.

checking valve clearance kz1000

At a minimum you will need a feeler gauge to measure the clearance. If any of the clearances are out of spec, the next step is to remove the shim (#1 in the graphic) and check its size.  The size is usually marked on the bottom side of the shim.  If there’s no measurement, the shim can be checked with a caliper. If the clearance is smaller than it should be, you will want a smaller (less thick) shim.  If the clearance is too large, you will want a larger shim.

How to remove the shim? KZ900′s and KZ1000′s have the shim over bucket design and the cams don’t need to be removed. Kawasaki makes a tool that depresses the bucket and allows you to remove the shim. There are after-market tools which are way less expensive, about $10 to do the job. Then there’s the least expensive tool - a really thick zip tie!  I’ll write about that in the future.

5. Ignition. Unscrew the spark plugs, put the caps back on then turn the starter over and look at the sparks.  Don’t touch the spark plugs while you’re doing this unless you want a shock!  Does every plug have a visible spark? If not, your wiring might need some work or the coils might be due for replacement.

Using a multimeter, check the voltage at the wiring to the coils. Voltage should be at or near 12 volts. If the voltage is significantly less there might be an electrical short or the wiring might just be old.

One way to get more power to the coils is Wired George’s coil mod. It’s not that difficult (I did it!) and you’ll get full power to the coils. Parts cost is minimal, maybe less than $10 if you get a good deal on the relay, fuse and wiring.

Ignition timing is important. If the timing is wrong it will affect performance. Here’s how to time your KZ1000 with a timing light.

Another ignition problem affecting the idle is the ignition advancer. The advancer has two springs and they lose their tension with age and mileage. Advancer springs in new condition are not available as far as I know. 

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Slightly shortening each spring will take up the slack so that the spark doesn’t advance earlier than it should.  That will help an erratic idle. Details on shortening the springs will be written up in the future.

6. Compression check.  

Buy or borrow a compression gauge with a 14mm adapter that will screw into the KZ1000′s spark plug hole.  Before taking measurements, warm up the motor. Taking the bike for a ride will warm it properly.  Unscrew all the spark plugs, put the caps back on each plug then install the compression gauge on cylinder #1. Open the throttle all the way, then push the starter button and watch the gauge. When the compression (psi) reaches its peak on the gauge, release the starter button and note the compression for that cylinder. Repeat for cylinders #2, 3 and 4.

Good compression should be between 150 - 190 psi.  All cylinders should have similar compression, within about 15 psi.  If the compression is less than 150 psi but all cylinders are running about the same pressure, it’s okay unless the compression is really low, like less than 100 psi.

I did all the steps above and my KZ still wasn’t idling the way I wanted! For my next step I removed the carbs and was starting to reinspect the intake boots even though they weren’t that old. I looked more closely at the first intake manifold and… the screws holding the manifold to the head were loose!  Well that can definitely cause a leak. I removed the manifold, cleaned it with carb cleaner then reinstalled it, making sure the screws were torqued properly. Then I checked the other three manifolds, they were all secure.

kz1000 intake manifold

I started the bike up and it immediately settled into a steady idle!  No need to adjust the idle and when the motor was warmed up.  My KZ was running almost as good as new.

Lesson - check everything!  It’s okay to check the easier things first but if you haven’t solved the problem you’ll need to check the more difficult things.

Happy riding!

Andrews Cam Specs KZ1000

Andrews cams are no longer produced for Kawasaki’s KZ900′s and KZ1000′s but they are still out there and come up for sale now and then.  Here are the specifications. 

kz1000 camshaft specifications kawasaki kz900 and kz1000

This is for KZ900′s and KZ1000′s.  Specifications for KZ650′s and KZ750′s are different.

Delkevic exhaust with straight muffler

These headers look sharp

Delkevic builds stainless steel exhaust systems and they’ve added this straight-style muffler to their catalog. Priced at $325 plus shipping, a bargain! Moto GPWerks sells stainless Yoshimura-style pipes in stainless for about $500 plus shipping. I have one on my KZ900 and it’s a great system. Japan Webbike has a great variety of exhausts for KZ’s. Some of them, the mild steel systems were priced in the $300 - $400 range awhile back. Now those prices are rising. Stainless and titanium system prices are getting quite expensive, the ti systems cost more than some of us pay for a used KZ1000!

Here’s the Delkevic straight mulffer system

delkevic exhaust for kz1000

Delkevic’s been selling this megaphone system for awhile. It’s priced great but that megaphone doesn’t cut it for some of us.

delkevic megaphone exhaust kz900

The weld right around the center of the megaphone just doesn’t look right to many of us who are used to Kerker and Vance and Hines pipes. Kerker still makes exhausts for classic bikes but the prices have climbed a lot - now about $800 for black painted systems. Vance and Hines in chrome are more affordable but there have been complaints about the quality of their systems.

Delkevic pipes can be purchased from Z1Enterprises and on e-bay.

Mikuni Smoothbores VM29

I recently completed an upgrade to my KZ900 with a spare set of cylinders bored out to 1015cc. We used stock KZ1000 pistons (70mm bore) with new piston rings and Webcam 118 camshafts. The bike ran nicely but it didn’t have the kick I was hoping for.

mikuni smoothbore kz1000

Luckily I had a set of Mikuni smoothbores stowed away. I gave them a cleaning and installed them on the bike.  Today I went riding and what a difference! When you look at a the throat of a smoothbore and compare it with a VM26, it’s significantly larger.  I’d characterize it as a ported carburetor. 

Mounted on the bike, smoothbores look similar to VM26′s. The easiest difference to note is the large nut at the bottom of the float bowl on the smoothbore that allows for changing main jets without removing the bowls. 

This set of smoothbores is jetted with 17.5 pilots and 120 main jets.  The pilots might be a little on the small size but they seem to work.  The air screws are about 1/8 to ¼ turn out - using Wired George’s jetting recommendations as a starting point.

Mikuni smoothbores were the high performance carbs for Japanese four cylinder bikes in the 1970′s and 1980′s. There are still many smoothbore carbs in existence and they’re getting expensive - count on a good working set selling for $500 at a minimum. There are other choices these days. Keihin CR Specials are getting a lot of attention. They are in short supply and sell for about $1,000.  Mikuni RS34′s are also popular and more affordable at $700 or so.

Parts for Mikuni smoothbores are still available - visit Z1 Enterprises website.

If you’re looking for bolt on performance for your KZ900 or KZ1000, get a set of smoothbores, Keihin CR Specials or Mikuni RS34′s.

KZ1000 Specifications

There are many inquiries about specifications for KZ1000′s.  Here they are:

1977 KZ1000-A1

Bore and stroke: 70 x 66 mm

Displacement: 1,015cc

Compression ratio: 8.7

Maximum horsepower: 83 @ 8,000 rpm

Maximum torque: 58 foot-pounds @ 6,500 rpm

Engine oil capacity: 3.7 liters

Motor oil: SAE 10W40, 10W50, 20W40 or 20W50

Front fork oil capacity (each fork): 180 - 188 cc

Front fork oil type: 10 weight (many riders suggest using 15 weight)

Carburetors: Mikuni VM26SS x 4

Spark Plugs: NGK B8ES or ND W24ES-U

Battery: Yuasa YB14L-A2

Tires: tubeless are the norm, still inner tubes should be used

Front tire : 3.25 x 19 or 100/90 x 19 metric

Rear tire: 4.00 x 18 or 110/90 x 18 or 120/80 x 18 metric

Fuel capacity: 4.3 gallons

Chain drive, 630 endless with 92 links, sprockets 15 front, 42 rear

1981 KZ1000 J-1

Bore and stroke: 69.4 x 66 mm

Displacement: 998cc

Compression ratio: 9.2

Maximum horsepower: 102 @ 8,500 rpm

Maximum torque: 67 foot-pounds @ 7,000 rpm

Engine oil capacity: 3.7 liters

Motor oil: SAE 10W40, 10W50, 20W40 or 20W50

Front fork oil capacity: 300cc per fork leg or 110mm from top of fork to oil level with forks compressed.  Filling from completely dry, 327cc per fork leg.

Front fork oil type: 10W20 weight (many riders suggest using 15 weight)

Carburetors: Mikuni BS34 x 4

Spark Plugs: NGK B8ES or ND W24ES-U

Battery: Yuasa YTX20HL-BS

Front tire - tubeless: 3.25 x 19 or 100/90 x 19 metric

Rear tire - tubeless : 4.25 x 18 or 120/80 x 18 metric

Fuel capacity: 4 gallons

Chain drive - 630 endless with 92 links, sprockets 15 front, 41 rear

Note - many other KZ1000′s and KZ900′s have similar specifications.  The KZ900 specs will be very much like the KZ1000-A-1, other than the displacement and the KZ900A has a rear drum brake.  

The KZ1000J’s specifications are similar to those of the KZ1000C.

The KZ1000-K1 and KZ1000-M1 are similar to the J except for a few things such as rear tire size (16 inch) on the K1 and M1 and rear sprocket size, which is 39 teeth on the K1 and M1.

KZ900 camshaft installation

Putting my KZ900 back together, the shop manual is great but getting the cams in right can still be tricky!  Here’s why.

The cam chain connects to the crankshaft and you can’t see if the chain and crank are connecting correctly.  The crank can be turned clockwise with a 17mm wrench and your other hand holds the chain up to verify.  Then you need to keep the chain taut as the exhaust cam is installed.  

Once the exhaust cam is installed, the intake cam gets installed and the chain links are counted (28) to make sure the two cams are timed correctly with each other.  At this point, the cam caps have not been tightened and the cams are floating several millimeters above the point they will be at when the caps are torqued.  The little arrow on the front of the exhaust camshaft should be level with the cylinder head deck once the cam caps are torqued. If the arrow is above that level, it’s likely the cam is timed one tooth off. That’s about 12 degrees retarded from the correct timing.  Your bike will run poorly with the timing that far off.

To correct the timing, all four cam caps should come off, the exhaust cam should be positioned correctly, then count 28 teeth after the arrow and time the intake cam (again.) Carefully torque the cam caps into place.  Then add the chain guide sprocket on top, in between the two cams.  Be very careful about dropping parts into the motor!  If you drop a bolt or other hard metal part, it must be retrieved before firing up the motor.

With both cams and the cam chain guide sprocket attached, turn the crank clockwise using the 17mm wrench at the crank.  Does the crank turn fairly easily? By the way, it’s much easier if the spark plugs are out. If the crank turns okay, keep turning a full 360 degrees then recheck the cam timing.  At the crank, the timing mark is a small “t” to the left of the 1-4 mark.

If the crank doesn’t turn with reasonable effort, STOP.  Something is jammed. A likely candidate is the cam chain, having slipped off the teeth on the crankshaft. Back to square one, remove the cam guide sprocket, cam caps and cams, then start over.  Another problem I had - at some point, after removing/replacing the cams, one of the cam bearings fell out of place.  The cams bolted in without difficulty, but when I tried turning the crank it wouldn’t go.  I removed the cams and saw that the bearing had been destroyed by being torqued down out of position.  Lucky for me, I had an extra cam bearing on hand.

kz900 cam timing diagram

This diagram is from the shop manual.  I highlighted in yellow some important items.  The arrow on the exhaust cam should be level with the deck of the head.  Go up one link from the arrow, that’s the 1st link and count 28 links. The 28th link should coincide with a mark on the intake cam sprocket.  If it doesn’t match up, carefully remove the intake cam and match the link to the sprocket mark.  While you’re doing this, keep the cam chain taut on the intake side, otherwise the cam chain might slip off the teeth on the crankshaft.  The timing mark at the crankshaft is #6 in the diagram.

Also note, once the chain guide sprocket (that roller in between the two camshafts up at the top) is in place, it’s hard to count the chain links.  I tried and gave up, it’s much safer to count them first then put the chain guide sprocket on.  If you forgot to count, take the chain guide sprocket off and check.  It’s better than finding out the timing was wrong by bending a valve.

Once you have the cams properly timed with the crankshaft, think about what a smart person you are for having done this correctly!