1979 A1 Carb Refurb - Idle Jet Adjustment - not working

wrote:

I few things in no particular order – just what pops into my head.Firstly:  It’s not necessary to have a “gauge” on each port for sync’ing.  1 Carb – 1 gauge.  Reduce the clutter!  Reduce the additional distractions.Although you discovered a Diaphragm that wasn’t positioned correctly; this would have no affect on the idle issues or cause excess fuel. 
Agree. Each cylinder has slightly different vacuum levels, but are close. I'll get some vacuum tees, combine 2 into 1, then use one manometer, 3 channels. It wasn't me with the incorrectly placed diaphragm, so that doesn't enter into this equation.

Regardless of Main-Needle height that the Diaphragm may have affected; no fuel can be delivered by the Emulsion-tube/Main needle until the throttle is opened considerably…enough to have the air velocity “Siphon” the fuel from the top of the E.-tube.   Fuel acquisition is completely different for the Idle and High speed.  Engine vacuum (“ Hg.) on the engine side of the throttle-plates is significant and quite different from the “Siphoning” affect (“ W.C.) on the air-filter side. It's the air velocity over the top of the emulsion-tube that draws "high-Speed" fuel. Focus on the inches Hg for your issues.
My diaphragms are fine. The previous post was from another kz owner.. Having said that, thanks for putting into words the physics involved between the two circuits.

Not sure what is meant by excess fuel “dribbling”. 
I noticed some 'wetness' on the external carb inlet boot on carbs 1, 2. When I pulled the carbs, I saw some fuel 'pooling' on the boot inside, making me think the bowl is leaking fuel directly into the cylinder, resulting in over-rich conditions.
 

All (idle circuits) jets and porting are above the fuel-bowl level.   It’s the “inches HG” that draws fuel up an into the idle circuit.  Not gravity. No Vacuum – No fuel.The answer to a previous question regarding a “seal” for the emulsion-tube is: No.
Thank You. And this is because the E-tube isn't in play at idle due to lack of Bernoulli effect? (low air flow at idle = low Bernoulli effect vacuum level?)

Are you using OEM or similar springs on your pilot-needles?  If the spring is too long/wrong gauge/too many coils it will feel like the idle needle is closing full stop when in fact the spring is stopping it from doing so.
I'm using Damien Ding carb kits. Also Keyster. All pilot-needle springs are same length, and the pilot-needle appears to 'bottom' correctly.

In this case,  your “3.5 Turns” is going to have too much idle fuel being provided!   In this case the pilot needle will already be partially open, so adding 3.5 turns………you get the idea!   
Not sure what you mean by 'In this case'? I did find on the carb that responds to pilot-needle adjustment that 2-3/4 to 3 turns out was the happy spot, based upon rpm rise. When I get all 3 carbs performing correctly I'll use a ColorTune for final adjustment.

Lowering the fuel level 2mm?  I see the simple logic but very much doubt this will make any difference.  A tuned, idling engine, will suck the bowls dry and not give any indication of the lowering fuel level until the engine stumbles and quits, when the fuel runs out.
I agree. But something is allowing the fuel to pool into the boot and cylinder. On my last 'rebuild' I used new brass from a new kit, including fuel inlet valve and seat. Not going to change level at this time. One step at a time to determine root cause.

Not a real concern at this time but something to consider next time you have the carbs off the engine:  www.kz1300.com/forum/bike-projects/3861-backfiring#29978 (or Search: intake leaks by scotch)A video cannot convey the subtle nuances of an idle but based on what I heard of your idle and transition – sounds good.
Yep. I gurantee all idle, transition ports are clean. Before installing new brass, did the 'Scotch Tool' flush and verified all 3 trans ports and idle are open and flowing freely.

That’s all I got.  Back to my project.
Whatcha working on?

 

scotch wrote:

Your wet boots may be due to "Fuel Stand-off".  Caused by the relatively quick opening and closing of the throttle.
This is an extreme example: