Dellorto Idle Jets?

So, last night I took a look a my Dells. I cleaned these up before my trip to France but I am still looking for the source of my popping on over run. My idle screws only seem to have much of an effect between fully screwed in, so they won't screw any further, to about 3/4 to 1 full turn out.

Fully in the engine stumbles, between that and one turn out it starts to run fine. After that further turns don't seem to make much difference.
Is this normal for Dells, or are the jets still causing issues?

 

The bigger the jets, the less turns out you need and the finer the adjustment to get it just right.
That points to big idles.

Euro or US Dells? (Tee hee).

 

Missing or worn seals/washers on the idle screw?

The dellorto book and this website was quite useful identifying what you should have.

https://sites.google.com/site/stpsgarage/TechnicalArticles/dellortodrlacarburetordisassembly


Ps. I'm an amateur but I found these were missing on mine and made a slight difference...but guess it could be a number of things.

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I ask because the idle circuits are very different in behaviour. The US bleed more air into the idle emulsion to run bigger idle jets.
The ex-Alpha 40's don't but still need a big idle to transition with larger than than ,30 vents.
So you could be unavoidedly running big idles in Euro carbs = rich idle circuit.

That's what I think anyway though I'm still playing at gradually turning my Alpha carbs into the US style.

 

That's interesting, didn't replace these when I had them off during the winter

 

I honestly don't know. How do I tell the difference between Euro and US?

 

The progression ports are different sizes.
https://thelatebay.com/index.php?threads/more-drla-40-nonsense.89412/

First post shows Alpha holes
Towards the end deefer posted 36 ports which are the same as US 40s.

You can take off a port cap screw and take a photo without taking the carb out. There is no seal. If there is fuel in there and engine wasn't just switched off you have a problem. Unlikely.

 

Just checking, Port cap screw, is that on the side of the carb?

My idles are 60, if I believe my notes from my January, mains are 122, I have some 130s to use when I get the popping sorted.

 

Yes, the big x head ones. RH carb had best access for a pic on mine.
Idles are a kind of base to then add mains to which helps run the small mains you have. It's far from as simple as adding them up though, sadly.

What size vents? I guess 28.

 

These .. but not hex on a 36..

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Not sure, my notes are lacking, which means disassembly or trying with my phone camera

 

Here's the beasties in question...

 

If you take an air filter off, a pic down the throat should catch the size, it's embossed on the top part.

 

Will try when this infernal rain stops

 

The port cober is the big x head above the idle mix adjustment. Apologies for typing hex head earlier, I'll edit that.
Those might be earlier ones. What kind of aux venturi do they have?
Like this?

Or this...

 

Top one, I'm sure.

Sadly, didn't take more photos when I had them out

 

Auto typing, my mistake, I've edited now.

 

This is the last one I have. Any use?

 

Ah-ha. Interesting for me at least to find out your hole sizes. They are most likely one or the other and if they are the bigger US size, your 60 idles may be just the ticket.

 

Those are flat head screws, kind look like Cross head/Philips...on mine