idle jets, mixed sizes Options

[Petepat]

Got a 1.7L engine with Dellorto Carbs which I took out the idle jets and notice on one side they are both 50 but on the other side they are marked 55 and 52 could there be a reason for this or a case of anything goes?

[technicalninja]

Run a compression test
I’ve seen carbs with different idles.. even mains
That owners have compensated for a low cylinder

I've seen that as well...
Every time I've seen intentionally staggered jets it's been on a weird application and a SHITLOAD of testing has been done with individual EGT probes to accurize the jets.
It's never been on idles however, always mains and airs.

I'm guessing this is not a 100+ hours of professionally tuned engine...

I solved a weird one over the phone with a friend of mine who operates a race preparation shop.
He had a "Legends" car that was a heat winner for the first couple of races that gradually fell off during the evening. This class of racing has many very short heats in a normal evening. By the end run this was which led the pack on the first heat was the caboose by the last heat.

Marty is knowledgeable and did multiple compression test and leak down during one evening. Leak downs were perfect all evening long where compression fell off in the rear cylinders quite dramatically over the evening...

Let the puppy cool down for an hour and all is well!

I had Marty stagger the valve adjustments .001 looser for each cylinder past the right outer one. Cylinder #4 had a valve adjustment .003 looser than cyl #1.
The air-cooled motorcycle engine was turned 90 degrees from normal installation and the rear cylinders heated up more than the fronts...

Fixed it right up!
Heat winner all night long now...

I'm betting someone, who didn't know what they are doing, decided to go ahead and use the jets they found. Maybe they didn't even check (or know to check!).
Having 3 different sizes is damn strange though.
The carbs would have come with identical jets, and someone had to add those at one time.
Got to be a back story there somewhere.

Now, doing a compression and leak down test should be THE FIRST thing you do when you're setting up carbs. If compression is screwed up it's going to be much, much harder to get the carbs right.
Maybe impossible...