Dellorto popping when cold

[Perazzimx14]

Got the SP tagged and insured and out for a test run yesterday. Bike starts and idles great but when cold pops through the carbs and had no power upon takeoff. It bogs, stumbles, pops then once at about 4,000 RPMS clears up and runs well. After a few miles when the motor is warmed up the popping is 99% gone.

Carb jetting (stock VHB's) 130 and 50
New Euro a/f screws set at 2-1/4 & 2-1/2 turns out. 
New needles clip in the middle setting
K&N 2:1 air filter
Dyna 3 ignition
Carbs sync'ed
Timing checked and is good

So do I raise the needles one notch and try again or is there something else to try?

[Antietam Classic Cycle]

On my Convert, I raised the needles up (clip in bottom notch). Adjust the mixtures screws for the fastest idle or just turn them out 1/4 turn, go for a ride, repeat as necessary. You may need to go larger on the idle jets. It has Bub mufflers as well as K&Ns IIRC?

[pete roper]

Go to a richer slide.

[Furbo]

On my Convert, I raised the needles up (clip in bottom notch). Adjust the mixtures screws for the fastest idle or just turn them out 1/4 turn, go for a ride, repeat as necessary. You may need to go larger on the idle jets. It has Bub mufflers as well as K&Ns IIRC?

What Charlie said - it's a bit lean. raise the needle. If that doesn't work, go with a 55 pilot.

[Perazzimx14]

Needles were raised one notch and in the driveway the popping is diminished. Test ride tomorrow

Thanks to all

[Antietam Classic Cycle]

Go to a richer slide.

IIRC, it already has a #40 (or should have) so already has about as "rich" of slide as is available for VHBs.

[travelingbyguzzi]

Check the seal (gasket) between head and intake runner.

[Chuck in Indiana]

Good replies.

. You may need to go larger on the idle jets.

Is all I had.

[Perazzimx14]

Check the seal (gasket) between head and intake runner.

They are newer but upon warm up today I'll spritz little carb cleaner around the gasketed areas to see if there are any breeches.

[Two Checks]

Depending on your altitude you may want to fatten the main. You will feel the difference at a wfo. Both my SP II and Cal III came with 130s and spit and sputtered. 142s cured it. Now with E10 they might like 145s.

[Charles in Lake Charles]

Also check the float levels. If the fuel height is too low, the engine will display a lean running condition, where the engine typically hesitates before accelerating or surges as the throttle is opened.

[Perazzimx14]

Depending on your altitude you may want to fatten the main. You will feel the difference at a wfo. Both my SP II and Cal III came with 130s and spit and sputtered. 142s cured it. Now with E10 they might like 145s.

617 feet above sea level. With most riding between 200 and 1200 feet.

[SED]

Posting this because it's a different solution. 

My LMIII would bog on takeoff and sometimes pop through the intake.  changing jets and slides and float level never quite solved it.  Solution was to replace the distributor advance springs and reset the timing.

Also put the stock airbox back on, but the advance springs really let if come off the line better.