MZ ETZ251 carb inlet size OD

[alexxx]

Hi,

Does anyone know the carb inlet spigot OD size?
I can't check my own bike at the moment as I put it to the back of my shed to work on something else but I will be buying a new carb to help get rid of the over run issue.
I will be using an OKO carb, they are a Kehin copy and good quality (only buy made in Taiwan versions)
I just fitted a couple of 30mm OKO's to my other bike, took a while getting the jetting right as no one else has used them in this model but they have made a huge difference so I want to fit one to my MZ.
The 30mm OKO's have a spigot OD of 34mm, I could use a 28 or 26 but the OD is the same for all.

[Puffs]

Removed

[alexxx]

Thanks Puffs,

I have just ordered the 30mm. I also questioned the wall thickness but it is ok, the inlet is more oval than round and there is enough material to support mounting.
I did think about the 32 as it has a larger body but the 30mm will suit the bike better.
I will ask a friend to help me make an adapter from alloy round bar turned down on a lathe and bored out.
Regarding jetting for my MZ, I will try with the standard jets which are main 138 and pilot 48, needle in mid position then see how it goes.
Hopefully the OKO can make a good improvement over the original, they certainly made a huge difference to my other bike.

[alexxx]

I have had an adapter made out of solid round bar PTFE, left the OD at 40mm, the carb is a tight fit at the 35mm id made for the spigot.
The PTFE should be a good material, it won't deform but is softer than alloy.
Will post info and pics once carb has been fitted and tested

[Puffs]

Hi Alex,

any experiences yet on fitting the OKO carb to the ETZ?

[alexxx]

Hi Puffs

Will be working on the new carb and inlet manifold adaptor very soon, been busy with other bikes I bought recently.
Looking forward to see if this carb will make a positive difference, will post more info when I fit and test.
The OKO carbs made a huge difference in my old T140, took me a while to figure out the jetting but it is good now, I replaced two huge ugly bings with a mess of cables and connectors, hopefully the MZ will respond even better.

Regards

[Puffs]

Actually mine does a bit of surging too. And a wise man helped me remember that a circlip had come off the original carb & went in to cause damage.

So another carb might well bring improvements.