VHBZ25HS carbs.

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Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

VHBZ25HS carbs.

Post by Tim Louth »

Hi all, I have a question.....well, 2 actually. Morini K1 Sport which is fitted with Dellorto VHBZ25HS carbs. Question one, Why are there sleeves fitted into either orifice of the carb? One black one and one white one. Is it just to change the diameter of the carb. Second question. The white sleeve has a step on one end. This step partially obscures the airway that runs through the carb and under the choke. Is this a design fault or are my sleeves in the wrong way?

A third question if I may. What size white sleeve should I be using. I see there are 2 options for my carbs at Eurocarb. Many thanks.
mbmm350s
Posts: 668
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: VHBZ25HS carbs.

Post by mbmm350s »

The white nylon manifold sleeve fits engine side (vacuum side) of the carb.
This acts as an interface to the aluminium spigot fitting on earlier Morinis. The black stub is used to adapt the VHB(Z) carbs to the rubber manifolds used post 1979. Ie it goes inside the nylon part.
In other words both parts are fitted engine side. Its not a design fault. There is no obstruction. They do not change the diameter of the venturi. There is only one sleeve for VHB(Z) 25mm carbs listed. Part 8792.
If you have any of these parts fitted air side then it's assembled in correctly. The parts diagram on the Eurocarb site should assist.
Hope that helps
Mark
Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

Re: VHBZ25HS carbs.

Post by Tim Louth »

Thank you Mark.
Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

Re: VHBZ25HS carbs.

Post by Tim Louth »

Hi Mark, talking about the white sleeves the ones that fit on mine are the 6977 ones from Eurocarb.
mbmm350s
Posts: 668
Joined: 22 Jun 2018 10:18
Location: Reading UK
Location: Berkshire UK

Re: VHBZ25HS carbs.

Post by mbmm350s »

Hi Tim,

Apologies, you are right 6977 shows on a parts list I have.
Its unusual for bikes with the rubber manifolds
to ever have to replace them though.

This confuses me.
Why are there sleeves fitted into either orifice of the carb
So long as both parts are engine side then there is no problem.

Mark
Tim Louth
Posts: 70
Joined: 23 Mar 2018 12:29
Location: Fareham, UK

Re: VHBZ25HS carbs.

Post by Tim Louth »

Hi Mark,
No, it was my bad. A long day in the sun and a couple of shandies left my brain slightly addled. The sleeves are in the same end and the threaded sleeve screws on to the other end. It just looked like the edge of the sleeves could possibly partially block the airway to prevent a smooth flow. There is not much info on my Morini and I wanted to be sure it was as close as possible to how it came out of the factory.
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