Carburetor cleaning

Removing the carburetors

In order to remove the carburetors you must first remove the airbox.

Selva Madeira 40/40XS/50 airbox.

After that the carburetors can be removed by opening four bolts (two in each carburetor), the bolt holding electrochoke body and disconnecting fuel hose. Opening the carburetor bolts can be a little tricky as there is not that much space. Be careful not to lose the metal part called "electrochoke mounting plaque" when opening the bolt in electrochoke body.

Bolts that needs to be opened in order to remove carburetors.

Dellorto carburetors removed.

Intake manifolds and a peek of reed valves. 

Cleaning the carburetors

I was positively surprised how easy it was to disassemble Dellorto OVC 34/30 carburetors, clean those and put back together. First you need to detach carburetors from each other by disconnecting the rods syncing them and fuel hose. After that you can open the fuel bowl by opening four bolts.
Then you can unscrew the main jet / diffuser and the idle jet.

I noticed that in one the carburetors the idle jet was not positioned in the middle, I think it's a manufacturing fault as changing the idle jet did not correct the problem. I carefully bended the idle jet a little so that it was in the middle of the diffuser. My engine has been idling quite roughly so hopefully this might help a little.

You should check the jet sizes, correct main jet size for Madeira 40 is 160, for Madeira 40XS/50 it's 180. The idle jet size is 65 for Madeira 40 and 70 for Madeira 40XS/50. (Madeira 40XS/50 has larger 38/34 OVC carburetors).

Carburetors detached and float bowls removed.

The main jet, diffuser and idle jet.

Idle jet is not in the middle.

Idle jet position fixed by bending it a little.