Carburetor UCD33 - enhance fuel flow

[sam2019]

not sure if this is the needle itself, in any case i ordered 10

 

[Sasa]

ok all good, found the needle, shortened it by ca. 1mm, also installed 135main and 20pilot. so far all good but tomorrorw long test ride.

First picture: if you can shim there, underneath that kind of circlip, you should be ok. Try one washer first, if not sufficent put two.

 

[sam2019]

First picture: if you can shim there, underneath that kind of circlip, you should be ok. Try one washer first, if not sufficent put two.

funny thing, the needle of the 350 has 3 rings for the circlip, the 500 needle only one so it cant be repositioned by stock means. with the very limited and shabby tools available my mechanic used an angle grinder to shave 1mm off the spiky end.

 

[Dool]

Needle length was not to be shortened, if it is out of the hole it no longer metering.

 

[Dool]

not sure if this is the needle itself, in any case i ordered 10

I does state " needle Holder".
What make is the Carby?

 

[sam2019]

What make is the Carby?

its a shabby website, half the pictures do not load so maybe they are out of operations

Welcome to Ucal Fuel Systems LtdUcal, Ucal fuel, Ucal fuel systems, Carburettor, carburettor, Fuel Pump, Air Suction Valve Fuel management system, Emission Control, MPFI, EMS, Oil pump, Water Pump, Service network, Indian auto component, Auto ancilla

 

[sam2019]

Needle length was not to be shortened, if it is out of the hole it no longer metering.

what is the difference between shortening it and adding a washer at the underside which pulls it in. in any case the bike runs fine.

 

[Dool]

I can not explain that, outside of my Pay scale.
@Sasa may step in

 

[Dool]

But he'd didn't so here it is.
You can see with these 2 needles that they are Tapered, they go into a hole and the further they come out of the hole the greater the hole size is, effectivly.
So raising the Needle is setting it up higher and therefore making that hole bigger all the time and it get bigger as it goes up as well.
Cutting it short does not change the Taper or the diameter of the Needle or I and others would recommend it.
The drill and Fine Sandpaper is what was done by Tuners, of course it would be better to have a selection of differing Taper/diameter Needles but reducing the size of the Needle with sandpaper is quick and easy to do, especially when it has just one.

 

[sam2019]

nice explanation, got it now

 

[sam2019]

those mikuni are compatible with ucd33 or is it just a sample picture?
they do look different but could still fit.

 

[Dool]

those mikuni are compatible with ucd33 or is it just a sample picture?
they do look different but could still fit.

pretty easy when they are held together, should be possible to determine whether it is the same.

 

[sam2019]

The bike is still knocking a little bit - not often but I still want that fixed so I put the needle to the drill and slimmed it with sand paper.
we will see if that works out ...

 

[aniruddhmalhotra]

The bike is still knocking a little bit - not often but I still want that fixed so I put the needle to the drill and slimmed it with sand paper.
we will see if that works out ...

Hey Sam

So I am looking for your help

First how well this modification worked?

You didn't tell the final results.

And I am in India

Can we please connect

I am looking for your guidance to do this on my carburettor Himalayan

This is my contact: xxxxxxx

I hope you understand how important is your guidance will help me.

Thanks for this heavily technical thread explained so easily.

 

[sam2019]

Can we please connect

No, I do not have the time nor do I want to give individual help outside this forum.
also: never publish any personal information publicly, like phone numbers etc.
And before asking for help maybe you introduce yourself, your bike, add a profile pic and do things that make it worthwhile to interact with you here! read the sections dealing with how to use this forum!