Z1OwnersClub GB

i have an old set of carbs , not sure if they are 26mm or 28mm
other than measureing them is there any other thing to check to identify them.

I beleive the top of the carbs are flatter on the 28's

BunnyZ, as Steve B says, you can tell the early model 28mm by their "flat tops" and the 26mm by their "high tops" at a glance.

However, the Z1R (approx. 1977-8) had a "high tops" 28mm that looks exactly like the 26mm. I don't know how you could tell the difference on these, unless you measure the inside throat. Maybe someone has a clue to distinguish one from the other.

Just to further complicate the issue, the 1974 Z2 (although rare to UK. Europe, US & Aus) initially had "flat-top" 26mm carbs.
RegardZ.

the 26mm(900a4 z1000a1/2) carbs have the mixture screw on the underside

the 28mm(MK2 ST later Z1R)carbs have the mixture screw on the sibe of the body

also the early 28mm carbs have only two screws holding the tops on the later have three

I have several sets of 'Z' carbs 26mm and 28mm,And some (With the superior pilot circuit) have fuel enrichener screws on the under side near the float bowl and some have mixture (air) screws on the side. And the only way to tell what venturi size they are other than visual comparison or experience is by going by the part number stamped on the mounting flange or by simply measuring the venturi at the end which goes in to the inlet rubber. Simple ??? .

Bunnyz, see if you can make out the number on the flange, as Z1015 has mentioned, and let us know. The number is on each flange and sometime in different positions. I take it you don't want to drop them off to measure the inside diameter. RegardZ

Have dropped them off , they have 3 screws at top , air screw at bottom of float bowls and most importantly measure 28mm in diameter, also have the open throttle stop screw at side of pulley , which according to manual tells me it is a 1979std 28mm carb,I have a 1977 kz1000, so might explain a bit on the popping exhaust i have....
many thanks for your advice

bunnyz, I believe they only fitted 28s to the z thou' so that should not be an issue with regard to it popping. Popping exhausts quite often point to an air leak in the exhaust system some where.

I have 26 on my kz1000ltd

if thats the case does anyone know the specifications for a 1977 kz1000 28mm carb i.e main jet and pilot jet sizes, ( will buy new ones) . as details i have are 1977 26mm, or know where i can check them out

bunnys, I swapped 26mm on my Z900A4 to 28mm off Z1000ST, nearly identical on the outside, the difference in venturi is obvious, first is nearly 27mm the other is nearly 29mm (don't remember exactly) measured easily on the engine side of the carbs, vernier caliper or even a ruler will tell you, as to the jets my 28s were fitted with 15 pilots and 115 mains , not sure if that's stock setup but my bike with custom exhaust was running very lean and was struggling to move on higher revs, I've fitted 17,5 pilots and 120 mains and runs like dream now, with jest is more or less matter of trying different sizes, running the bike and checking the plugs colour if what's fitted is good enough, it's easier if your bike is completely stock.