Here’s a comparison beween the various carbs found:

A1 Samurai carbs are always 22mm and require their specific covers. The calipers show the inlet stub inner diameter.

Here is the covers for them.

Now for the A7 first series of carbs. Early A7 had Vm 26 SC Mikunis, these also require the use of the correct covers.

This is the later type of covers, with the much bigger inlet stub (around 34 mm). These are the ones you want to use if building a tuned or race version.
The carbs that fit are 28 mils VM 28 SC, these have a different jetting arrangement, primary type with a shroud and round main jets.
This cover has the oil injection welded shut.
You can make the 26 carbs fit these stub by removing the phenolic bush at the inlet, but there will be a small step between the stub and carb.
Note that there is also different version of the crank cases for each of these carbs & covers!
Buyers beware! Most people selling their stuff on eBay have no idea of these differences.

Here it is on the steep slopes of Lavaux, Switzerland, on the return leg of the trip.

Needs to be done:
Apart from a sticky RH throttle slide, nothing much.

Carbs: repair/replace RH throttle slide stop… obviously still not quite straight enough. You only feel it at WOT.
Petcock: really needs a new set of joints, specially the tank/cock gaskets. It weeps a bit.
Exhaust: need to find a way of keeping my baffles inside securely.
Seat: needs a new cover when cash is at hand.
Stickers: A1SS needed, Again when cash is in surplus. André Okazaki at reproduction decals is the man, do not hesitate to contact him.
Tires: could do with a new pair of BT45s to enhance the ride.
I’m also playing with the idea of fitting signals and a scrambler bar, I have one at hand, more enduro like (lower than the original), but why disturb something that works well?

If you don’t a position ring (the half moon that keeps crank bearing into place)… it’s OK, they get lost a lot, but they need to be there.

Just use  a H1 ring, they’re the same.

Part # = 14013-1004
Part Description = POSITION RING
Model Count = 179
A1 N/A 250 SAMURAI DUAL PURPOSE 
A1R N/A 250 A1R STREET 
A1SS N/A 250 SAMURAI SS DUAL PURPOSE 
A7 N/A 350 AVENGER DUAL PURPOSE 
A7SS N/A 350 AVENGER SS DUAL PURPOSE 
H1 N/A 500 H1 MACH III STREET 
H1B 72 500 H1 MACH III STREET 
H1C 72 500 H1 MACH III STREET 
H1D 73 500 H1 MACH III STREET 
H1E 74 500 H1 MACH III STREET 
H1F 75 500 H1 MACH III STREET 
KH500-A8 76 500 KH500 STREET

Part # = 41034-007
Part Description = FRONT BRAKE DRUM ASSEMBLY
Model Count = 13
A1 N/A 250 SAMURAI DUAL PURPOSE 
A1SS N/A 250 SAMURAI SS DUAL PURPOSE 
KH250-A5 76 250 KH250 STREET 
S1B 74 250 S1B STREET 
S1C 75 250 S1 STREET 
A7 N/A 350 AVENGER DUAL PURPOSE 
A7SS N/A 350 AVENGER SS DUAL PURPOSE 
S2 72 350 S2 STREET 
KZ400 74 400 KZ400 STREET 
KZ400D 75 400 KZ400D STREET 
KZ400S 75 400 KZ400S STREET 
KZ400-S2 76 400 KZ400 SPECIAL STREET 
KZ400-S3 77 400 KZ400 SPECIAL STREET

Thanks to III from the KTW Board

“NTN still list their EC bearings as available- these have two orange plastic rings in their outer races which took up any difference in expansion between bearing outer race and crankcase. Kawasaki used them for their road racers such as H1-R, H2-R and KR750. H1-R cranks used all-roller main bearings, and later apparently switched to cranks with small main roller bearings and large main ball bearings; I have seen one such crank brand-new in the original box.
For the H1, you would require three EC6205/C3, two EC6305/C3 and one EC6305N/C3.
For the H2, three EC6206/C3, two EC6306/C3 and one EC6306N/C3.
For S series, three or five (depending on whether you have a four-bearing or six-bearing crank) EC6305/C3 and one EC6305N/C3.
For the A1/A7, three EC6305/C3 and one EC6305N/C3.
ONLY NTN make these bearings, so be sure to specify NTN when ordering from your friendly bearing supplier.
EC, by the way, stands for “Expansion Compensation”.

The roller bearings for the H1-R are the NTN ECNJ205G1/C3 and ECNJ305G1/C3, and these may also be available, but these are FILTHY expensive………”

This solves my problem of finding good enough bearings for the A1R… now where to get them?

1967-1968 models
These motors have the 2-part disc valve, with a pin retaining the disc. Disc are made in phenolic resin with a steel center.
Samurais have a 2-tone tank with knee grips and white hand made stripe, they came in candy red or blue. Combination unit for tach/speedo.
Side panels are in aluminium grey with a thin “Autolube” sticker.
Avengers  have a chrome panelled tank with knee grips and came in blue. Combination unit for tach/speedo. Side panels are in the color of the bike.
All have a deep, almost valanced, chrome rear fender.
These bikes are sought after because they look… well… vintage! But by the end of 1967, this design was already a bit outdated.

1968 models
Speedo and Tach are separated and round.
new headlight shape, similar if not identical to the early H1.
Tanks keep the previous design but don’t have chrome panels or knee-grips. The paint scheme is the same, with a hand made stripe.
Side panels are in the color of the bike, with a large trapezoidal sticker.
Similar to a 1967 Samurai tank sans knee grips. Red or blue, see my Scrambler to see the color. The colors are different from the previous year and have a LOT of metal flakes in them.
New Stainless steel rear fender, thinner design, will last until the end of production.
Note: these are the models that also were sold in 1969. Think of them as parts bin specials.
Low production run: ~ 1’500 made.

1969 models
New disc using a gear-like sleeve to  link them to the crankshaft. Much better design. The discs are entirely in resin.
the front fork has a new internal design, with new fork ear design, less triangular and with a reinforcement on the inside.
Speedo and Tach are separated and round.
New style (fatter)brake and clutch hand levers.
New style of rear light with round reflector part on top.
New style of hand controls (the markings on the LH are different).
Tanks keep the previous design but has a new oval paint scheme, red or yellow. The red is a very nice shade of candy burgundy. Tank paint scheme was obviously changed mid-year, as there are two different brochures.
New design for the gear changing drum.
New design for the rear swinger, specifically the bush.

350 Avenger gets new 28mm carbs, upping the power to 42 HP and new pipes (with a C engraved, previously there was an A. Don’t know where the B got lost)

1970 models
New tank with a rectangular form. Paintjob is an adaptation of the previous year. The red color is again different, not burgundy, but a “straighter” red. Tank has a recess on top (what for?).
The 250 gets a new head gasket in copper only (previously instead of a asbestos-copper mix).
The 350 has new rings with an expander ring under the 2nd ring. Colors are red or yellow, again different from previous year’s shades.

1971 models
New tank, same shape but no recess on top. New paintjob, white for all models with gradient-like stickers on side of tank and sidecovers.
Accents are blue for the 350 and orange for the Samurai. Last model year before the S1 and S2… End of the line.

If you’d love to agree or disagree with the above, just drop me a line here in the comment section.

Kawasakis of the period didn’t have matching frame/engine numbers. Engine number is usually between from 50 to 200-300 range from the frame #, although later the diffrence ranged up to ~1’500.
The motor numbers are always higher than the frame numbers, same thing applies to the Triples for example. This is due to the way they made them at the factory, when ramping up production: motors might be more complex to assemble, but actual assembly is faster.
So when assembly started, the gap between the numbers was low and went up as the year went on. Numbering didn’t stop between the change from model year to model year. The last ’71 models had a large number difference between motors and frames. The early 67 models had a very small difference in numbers, maybe due to more precise assemblies and the fact that it didn’t sell, the company wouldn’t be submerged in leftover motors.
Since there were modifications to the motors specs (more on that later), it could well be possible that Kawasaki reset the numbering at the the start-of-model-year numbering. In this case the next model year frame #, were in fact just a few up on the last motor # produced the year before, to start a new model with a “round” number. The leftover motors were probably used for under warranty exchanges.
So the difference should always be greater at the end of the year than at the start. And there SHOULD be a very very few matching numbers bike, with very early model year numbers.
Hope it makes sense…

So here’s the list: it pertains to the frame numbers only. These are from Kawasaki themselves and can be trusted.