Pilot / mixture screw question. 32mm Bings

Hi,
I have a question, and before we start the bike is 750KM's away still ( I couldn't load it, single handedly, without ramps so its still in Switzerland - I am not) but

Im just trying to ascertain the reason the bike is only firing on a single cylinder..seemingly

If I have an air leak on my Idle / Pilot mixture screw needle ( i,e no / deteriorated O-ring) will that :

1) read "0" pressure when connected to a vacuum gauge - whilst the other side reads a value of about -0.03 bar (or something)
2) Not provide any fuel into the air-flow (i.e into the cylinder) even though fuel is present at the nipple.
3) No fuel into cylinder = Very low running temp on the cylinder (even though there is a spark from the plug) (and Ive pulled both plug cables independently - and this side is definitely not in operation.

after inspection the O- ring on the pilot /mixture needle was badly deteriorated and I concluded that this was maybe the issue..

Opinions


Other than that, this bike that has been sat in a garage for 6 years is starting to appeal to me again...

Thx

F2L

It is highly unlikely that a deteriorated/missing o ring on the idle mixture screw will cause a zero vacuum (not pressure!) reading on a vacuum gauge. If it truly is zero whilst the engine is running then that may point to something engine related, or perhaps a blocked vacuum take off port, or maybe even a faulty gauge.

Have you checked fuel in both carbs and float heights?

Doe the engine fire on both cylinders when revved above idle?

Have you checked compressions?

It may have been better to add this to your already existing thread to avoid duplication of comment/effort from the collective - I seem to recollect that this issue was covered before?