Setting up Dellorto’s

[billwill]

The 'holes' in the blanking screws are possible hexagonal and don't go right through, so that an allen key can be used to screw them in ??

[lomh 13]

Thank you for the replies.
OK for the vacuum taps, it is correct.
But for the others, idle air bypass screws, it seems there are not fited on all the DHLA.
Mine have only 3 progression holes and perhaps there is no screws. I can't see if there is a hole in the bottom of the well (I don't know if it is the correct word).

[lomh 13]

I have made some check on my DHLA and there is something wrong on rear carb.
When I close totaly one or the two iddle mixture screws on the rear carb, the engine is still running.
When I do the same on the front carb, the engine stops.
What I have to look at in this carb ?

[lomh 13]

Hello All
Today I have re routed the engine breather witch was pluged in the air intake, next to the rear carb. As the n°4 cylinder spark plug was dirty I believed it was the culpit.
But when testing the engine, I've unplug the HT leads on each cylinder.
For n° 3 and 4, the idle speed decreases.
For n° 1 and 2, the engine stalls.
For me its confirm that the engine runs more on the two front cylinders than the others.
The sparks are good on the four cylinders, tested with that ;

Compressions are good on the four cylinders.
So I think that I have to look at the rear carb.
Any ideas before disassembly ?

[mbell]

Having the same results for cylinders 3/4 suggest it common to the carb rather than engine cylinder, so i would be looking at thing that would effect the whole carb:
- Are the carbs correctly balanced? If not I'd start by balancing them.
- What is the fuel level in that carb? Is it correct/too low? Does it need adjusting or is there a problem with needle valve or blocked inlet filter.