1973 Z1 900 Super 4
Frame Number Range: Z1F-00001 to Z1F-20000
Engine Number Range: Z1E 00001 to Z1E 20000
Frame Number Range: Z1F-00001 to Z1F-20000
Engine Number Range: Z1E 00001 to Z1E 20000
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Z1's produced in August of 1972 have matching frame and engine numbers.
All other Z1's have close Frame/Engine Numbers, this range was anywhere within 250.
Engine & frame production followed a sequential numbering system, From 1 to 20000.
Frames were ready for the engine when it was time for assembly on the production line.
Engines were more time consuming to assemble and test, thus frames typically have a lower number, but not always.
All other Z1's have close Frame/Engine Numbers, this range was anywhere within 250.
Engine & frame production followed a sequential numbering system, From 1 to 20000.
Frames were ready for the engine when it was time for assembly on the production line.
Engines were more time consuming to assemble and test, thus frames typically have a lower number, but not always.
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All Z1 Engine Numbers are stamped on a 65mm by 14mm raised platform on right side of engine.
All Z1 engines were painted black, with polished fins and covers left in bare aluminum.
Kawasaki received complaints the engine paint would flake off within months of purchase.
All Z1 engines were painted black, with polished fins and covers left in bare aluminum.
Kawasaki received complaints the engine paint would flake off within months of purchase.
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The frame number is stamped on left side of headstock. Numbers are stamped to bare metal.
The frame number is also printed on the conformity sticker located on the right side.
This manufacturers conformity sticker was required for US imports. It has info including weight and the date of manufacture. This date on the sticker reflects when it was actually made, not when it was exported, imported or sold. The original sticker never will come off unless intentionally removed.
The frame number is also printed on the conformity sticker located on the right side.
This manufacturers conformity sticker was required for US imports. It has info including weight and the date of manufacture. This date on the sticker reflects when it was actually made, not when it was exported, imported or sold. The original sticker never will come off unless intentionally removed.
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The Z1 colors: Orange on Brown or Yellow on Green (only available in Europe).
USA & Canada only received Orange on Brown, Europe had both color options.
Official color names: Candytone Brown or Candytone Green. Kawasaki made no mention of Orange or Yellow.
USA & Canada only received Orange on Brown, Europe had both color options.
Official color names: Candytone Brown or Candytone Green. Kawasaki made no mention of Orange or Yellow.
Z1 Speedometer & Tach have a wide gap between mph and ND / x1000rpm and ND.
ND is (Nippon Denso) the co. that made them
(The Z1A has a close gap between mph ND / x1000rpm ND)
ND is (Nippon Denso) the co. that made them
(The Z1A has a close gap between mph ND / x1000rpm ND)
Lights order NEUT FLASH BEAM OIL
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The tachometer font of the 7 changed later in production of the Z1. Straight 7 was used first, later a curved 7.
The Position of the speedometer marker at the 20 mph also changed later in Z1 production.
The Position of the speedometer marker at the 20 mph also changed later in Z1 production.
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Carburetors were Mikuni VM28SC. Carbs would be marked 1470 or 147 with 2 or 3 under the 147
Choke Lever has a black cap. The ON and arrow highlighted in red paint.
Choke Lever has a black cap. The ON and arrow highlighted in red paint.
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Z1 has 155mm long Kawasaki Tank Badges (122mm between the screws)
Rear brake lining had NO wear indicator. All Z1A & Z1B had the wear indicator.
The last few thousand 1973 Z1 produced would have the updated casting as stock ran out.
These have no useable range decal and the indicator arrow was not present.
The last few thousand 1973 Z1 produced would have the updated casting as stock ran out.
These have no useable range decal and the indicator arrow was not present.
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No gear change pattern (1-N-2-3-4-5) embossed on the chain case cover near gear shifter.
The last few thousand Z1 produced would have the updated casting as supply of the old cover was exhausted.
The last few thousand Z1 produced would have the updated casting as supply of the old cover was exhausted.
Z1 & Z1A used a chain oiler, Z1B did not. The chain oil tank is under the left side cover.
Z1 used two style labels. Earlier being without the SAE 90.
Z1 used two style labels. Earlier being without the SAE 90.
The plastic drain cap on the bottom of the tank changed from white to black. White plastic being first used.
Reservoir cap has "BRAKE FLUID" cast in metal
Z1 Tail section document tray has two variations, the first used has NOTE & engine oil capacity is 3.7 Qt
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The Z1 Frame Does NOT have a hole in the sheetmetal frame brace.
If the hole is there the frame would be a Z1A, Z1B or a replacement frame.
If the hole is there the frame would be a Z1A, Z1B or a replacement frame.
The engine case has some subtle differences in the casting. For example the lower corner of the engine case.
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Just because the engine is painted black does not mean its a Z1
The cylinder head has a few variations, the most obvious is the 903cc marking. Z1 cylinder heads have the 903cc cast on a raised block that the z1a z1b and kz900 do not have. Both versions with and without a gap between 903 and cc are Z1 only.
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Z1 Exhaust was chromed whole with no band around the muffler connection covering welds
There were 2 versions of cast aluminum Lower Front Fork legs.
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Headlight fork ears brackets have smooth seams, the Z1A has a raised seam.
The font brake caliper mounting bolt has 3 variations.
Earliest has a small hex star inside the mounting bolt. Then came a larger star, finally no star.
Earliest has a small hex star inside the mounting bolt. Then came a larger star, finally no star.
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Z1 had 2 brake splitter variations.
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(2) Variations of the Engine Oil label was used.
The 1st label has 3.7 quarts (3.5 litres) & 'MS'
This was revised November 1972 to 4.2 quarts (4.0 litres) and 'MS' was removed
The 1st label has 3.7 quarts (3.5 litres) & 'MS'
This was revised November 1972 to 4.2 quarts (4.0 litres) and 'MS' was removed
Only 1 label was used for chain warranty on the Z1. Label was changed late Z1A adding 3,000 miles printed on the label.
The Petcock has 2 variations.
1st version has aluminum outlets for the fuel lines, 2nd version was brass.
The lever was also modified to add a o-ring to stop potential fuel leakage.
1st version has aluminum outlets for the fuel lines, 2nd version was brass.
The lever was also modified to add a o-ring to stop potential fuel leakage.
3 versions of the owners manual exist, with slight variations.
August 1972, November 1972 and March 1973.
Other countries had manuals printed in their language such as Italian, French & German
August 1972, November 1972 and March 1973.
Other countries had manuals printed in their language such as Italian, French & German
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Z1's have 32" wide handlebars, 5" rise, 7" pullback.
On the right side of the frame, there is a welded bracket to add an adjustable steering damper.
The frame has pre-made holes for adding an optional engine oil cooler. Riders who lived in hotter climates or areas with heavy city traffic felt it a necessary add-on to prevent overheating of the air cooled engine.
Rims have 40 spokes.
The original 12 volt battery was a Yuasa 12N
On the right side of the frame, there is a welded bracket to add an adjustable steering damper.
The frame has pre-made holes for adding an optional engine oil cooler. Riders who lived in hotter climates or areas with heavy city traffic felt it a necessary add-on to prevent overheating of the air cooled engine.
Rims have 40 spokes.
The original 12 volt battery was a Yuasa 12N
The Z1 was sold worldwide. Various countries had different regulations for motorcycle manufactures to comply with. Slight variations of Z1's exist from country to country since Kawasaki had to conform to specific regulations. Euro models featured a seat strap for a passenger to hold, Long rear fender, km/h speedo, fixed foot pegs, reflectors were not required and not used. Germany used a Metal riveted tag on the frame instead of the white conformity sticker of all the US models. Italy has a (*) added to the frame number.
The factory produced 4,846 Z1's August to the end of December 1972. Remaining Z1 production was January thru June 1973.
Z1 Specs: 903cc Engine, 82hp. Top speed over 125mph. 1/4 mile: 12 seconds. Weight 506 lbs.
The factory produced 4,846 Z1's August to the end of December 1972. Remaining Z1 production was January thru June 1973.
Z1 Specs: 903cc Engine, 82hp. Top speed over 125mph. 1/4 mile: 12 seconds. Weight 506 lbs.
Don't see a white sticker on your frame headstock?...You probably have a replacement frame.
Frames were painted then stamped, frame stamps are bare metal not painted over.
Replacement frames do not have white Identification stickers. MADE IN JAPAN is visibly stamped in the frame.
Remove the gas tank, you probably will find a part number tag on the upper tube. Only found on replacements.
Faint impressions, crooked numbers, variations on font and size, are all clear signs of a replacement frame.
A replacement frame will significantly lower the value of a Z1.
If you have an estate to liquidate or non Kawasaki motorcycles here are websites that might be able to help you. https://www.weekendestatesales.com/ https://www.wantedoldmotorcycles.com/