Z50 K0 and K1 carbs and Petcock

Broz

Broz

Member
Hello all. Would anyone have a picture of a Z50 K0 carb or describe the difference between a KO and a K1 carb please? Also the difference between a Z50 K0 and K1 Petcock. If you have pictures that would be awesome too.
Thanks for any help here.
 
kirrbby

kirrbby

Well-Known Member
A K0 z50 carb looks just like this one...but maybe not as dirty and rusty. They're are minor, but important differences between the K0 version...and the K1 and K2 parts.

1678457468295.png
 
kirrbby

kirrbby

Well-Known Member
A z50 K0 petcock looks just like this one. Except this one has something weird on it where the fuel filter should be.
K0 and early K1s used this style petcock.

1678457776145.png
 
kirrbby

kirrbby

Well-Known Member
The carb pictured above has the wrong rubber boot on top also.
That must be a aftermarket boot...or something. Doesn't look right to me.
 
kirrbby

kirrbby

Well-Known Member
EVERYTHING in hambone's pic looks correct to me, EXCEPT for the drain screw on the carb.
That drain screw is the 2nd iteration. The one in my pic, is the 1st...K0 type.
 
Broz

Broz

Member
Thank you Hambone and Kirby. So on the Z50 K0 carb. The differences between the K0 and K1 is basically the K0 has the flat faced drain knob and a cast or pot metal drain nipple, but the K1 has the brass drain nipple and smaller rounded faced drain knob? Anything else? I think I have two K0 carbs, but want to be sure so I don't misrepresent them.
 
kirrbby

kirrbby

Well-Known Member
Those ARE the basic differences that folks will spot.

The fuel inlet nipples changed a bit on the newer carbs...but I'm not sure of the specifics. And...K2 carbs...and maybe some late K1s, have the air/fuel screw that is kinda shielded...inside of a tube. That feature is definitely NOT K0, and a purist would spot it.
 
Broz

Broz

Member
Yes, K2 looks like same carb, but has shrouded air mixture screw.

Here is what I have. And I think these are K0 carbs?

20230310_094809.jpg
 
Broz

Broz

Member
Thank you!

For reference. The early fuel nipple that is cast or pot metal, has a smaller hole in the bowl and the nipple can not be changed to the later design with the brass nipple as the hole in the bowl is larger for the brass design.
 
hambone

hambone

Active Member
kirrbby said:
EVERYTHING in hambone's pic looks correct to me, EXCEPT for the drain screw on the carb.
That drain screw is the 2nd iteration. The one in my pic, is the 1st...K0 type.
Click to expand...
Kirby
Do I need to be looking for a different drain screw, is it not correct for an early K1?
 
O

OregonMinitrail

New Member
I’ve found that the thread pitch of the fuel and air mixture screws is different on the 68 carbs. Apparently, Honda adopted new thread pitch standards around this time. As a result, I can’t find new mixture screws that will thread into my carb.
 
C

CLEC66

Active Member
OregonMinitrail thanks for bringing that up, I’m restoring a 68 z50 and the Keyster rebuild kit includes both idle and mixture screws and neither one will thread into the carb. Guess I’ll clean and polish the originals unless someone chimes in.
 
kirrbby

kirrbby

Well-Known Member
I talked with Gary Lewis today...he confirmed also that the early carbs have different thread pitch on the screws...including the drain screw. I remember trying to buy a thread repair kit for the bowl screws on a early CT70 carb at my local nut and bolt supply...they measured the pitch of a screw...told me the oddball, vintage, thread pitch...and said..."sorry"
 
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