Carb spits gray smoke, stalling

[AgentX]

Hi all-

Working on my first bike/build, a 350 Royal Enfield.  Has a VM24 Mikarb round-slide, a licensed copy of the Mikuni VM24.  I have a free-er flowing K&N pod filter and muffler than stock, and have upjetted from a 25 pilot/90 main stock combo to a 30 pilot/105 main as a starting point.

At the moment, the bike starts first or second kick when cold.  (kick-only, no e-start)  It will not start with the choke engaged and dies if you engage the choke once it's running.  (I think it's technically an enrichener, but the lever says "choke.")

When warm, it gets harder to start and tends to pop and spit gray smoke through the air filter and stall out with a little kickback.  It also frequently does this if you whack the throttle open suddenly from idle.  (Fairly normal for a primitive slide carb without an accelerator pump, to my basic understanding, due to the sudden lean mix, right?)

I thought it was over-rich due to the choke issue, reasoning based on the enrichener making it die instead of race, along with seemingly having a good mix for cold starting without the choke.  But supposedly the gray smoke is a sign of a lean mixture.  What gives?

Finally, it like to die off silently as you brake to a stop.  The harder you brake the worse it seems; you can counter it by revving as you apply the brakes.  I don't know what's up with this...clutch drag, fuel sloshing forward during braking and starving the jets due to improper float level?

Thx for the assistance and expertise; I am only an egg.

MD

[Gissmo50]

It sounds to me like your pilot is to large you should need choke to cold start so once it's hot and you slow for lights ect your mixture is to rich it idle for hot running which is why your having to rev it and open the slide and give it a little more air. Carbs are a dark art and take a while to get your head around

Sent from my R800i using Tapatalk 2

[AgentX]

Yeah, I wanted to start with a 28 pilot but no one has one in stock.  I figured the 30 would be OK if the air bleed screw was properly adjusted.  Right now it's behaving decently at 2.5 turns out from full rich.

Whatever the "mechanic" had put in prior was waaaay too rich, because the air screw was fully out and it was still slightly rich.  I don't know what number it was and had to EZ-out it to remove it.

I was hesitant to use the 25 because I keep reading slightly rich is safer than lean...

[Gissmo50]

Rich is better than lean mainly because you can burn valve seats away and I've seen people burn right through piston crowns with very lean mixtures, the easiest way to find out is on a dyno I'm afraid all the time not spent on one is just guessing

Sent from my R800i using Tapatalk 2

[AgentX]

Rich is better than lean mainly because you can burn valve seats away and I've seen people burn right through piston crowns with very lean mixtures, the easiest way to find out is on a dyno I'm afraid all the time not spent on one is just guessing

Sent from my R800i using Tapatalk 2

India doesn't have micrometers.  Motorcycle piston clearance is gauged by thumb.  Dynos, I'm afraid, are way out.

I still can't figure out why it seems to be running rich, but the gray smoke indicates lean (according to Bullet mechanical guru in the US who I actually trust).