Cb350 vm30 carb tuning issues

[Jrasm]

I have a 1970 cb350. Recently I bought 2 prejetted VM30s from DCC. Right now i've got the idle circuit tuned and synchronized. I think.... I've never done this before, but I found all the threads on how to properly synchronize them using drill bits to make sure the idle speed screws are the same, and popsicle sticks to make sure the slides lift together.

The setup i've got in there now is:
Pilot: 35
Jet Needle: 5F4 (2nd richest clip setting)
Needle Jet: P-5 Primary-type
Main Jet: 155
Idle Air Screw: 1.5 turns

This seems too work fine at idle. As soon as i even touch the throttle it'll begin popping and very quickly die unless i let off the throttle. I think because of a lean condition, although i'm not really sure, i get only a very short time like this before it dies.

I'm pretty sure the idle is right, i've bought 20's, 30s 35s 40s 45s and the 35s seem to run the best for me and allow the idle screw to be around 1.5 turns.

So i'm not sure what to do about the mid-range circuit. I'd appreciate any advice anyone may have.

 

[adriannarnold]

Sounds to me like you are running rich. If it was lean it would rev uncontrollably very high. It has been a while since I messed with a 350 but when I had mine I am pretty sure I ended with 37.5 pilots and 130 mains with the clip in the center. Looking back it could probably used a bit more fine tuning, but that will be a great starting point for you.

Are you running pod filters? Do you have a very strong fat white/blue spark?

 

[Jrasm]

yep, pod filters.

Just got some bleed-type P-6 and P-8 needle jets in the mail today, and turns out i actually had p-0 in there now from the manufacturer. but from what you're saying, i may be going in the wrong direction.

I'm in Albuquerque at 5300 feet, so it would make sense that everything i try based on what i've read online puts me too rich. I bought a bunch of main jets so i'll try leaner.

As for the spark, i just put new coils on, but i'm using the original condensers. the spark seems right to me, blue and white, but i dug into the points today and notice a lot of sparking in there so i may still be delivering a weak spark. unless the sparking is normal. i'm still learning.

 

[Jrasm]

Turns out my issue was electrical supply. I had been kick-starting it and it turns out the battery i had on it was dead. With the dead battery, the generator created enough to idle ok, but as the electrical demand increased, it was just too great for the charging system to keep up with. So, a new battery fixed it and i've got a high-output charging kit in the mail.

Thanks all,

Jeff

 

[Rocan]

you're still running way rich with 155 mains unless if you are overbored with a REALLY well tuned exhaust and other mods. Weld on an exhaust plug into your exhaust and put on a wideband and I bet you its off all over the place. VM30s take a lot of tuning to get right. As it is, I bet you that if you were to throw stock carbs and airbox back on it will run far better.

 

[Jrasm]

That would be nice, although i'm kinda screwed in that area. The original ones are pretty fried even after some significant cleaning. Also the bike hasn't moved in 30 years and when it was put away, it was done with the carbs full of fuel and about an inch or so of gas in the tank.

Fortunately for me, in the process of figuring this out i bought a variety of jets, so i'll just keep testing and changing until i get them right.