Vm29/cb750 dohc (I know.....)

wow that was fast!!
ok so i am getting about 25. can't remember what exactly. after bench sync w/drill bit it was a difference from 29 to 20 between all. i got those to be all equal at 25"hg
could too much vac be an issue?
i was just playing around with my boys 1981 small block chev and changing ignition timing changes map. is that going to be the same case with these little engines.
maybe my ign timing is off?
 

It's hard to see but black is the only way to describe. I changed plugs 3 times throughout the process and even went with some 7's instead of 8 as called for by factory.
anyone wanna come over and magically get it right for me? Pop's on me!

Looks oil fouled to me

I sure hope its not burning oil since i had all the valve seals done. since i didn't have tools to properly measure guide clearance i left it up to the machinist. i did put new oe valves as well. he did grind into the valve seats which apparently is a big no-no since it removes the coating on the seats??? maybe?? it was a challenge to get cv carbs working decent as it was on the lean side with white plugs. those carbs have a press-in pilot. could have started to burn things up a bit.

I went back thru this post and I did not see you listing what size main jet you are running.

If the main is too big then it will be rich in all circuits. Remember that the jetting recommendation for these are for race engines, these are race spec carbs so jetting is probably fat on your stock engine.

Have you done any high gear plug chops?

It certainly looks rich ? not sure why you think grinding valve seats is a problem (this is standard practice when overhauling a cylinder head)
Not sure why you moved away from the stock carbs, I used to run a Harris Magnum with the 1100 version of your motor (1123 Wiseco's, ported, pods, free flowing exhaust etc) the standard carbs with a stage 3 "dyna-jet" kit worked perfectly and it pulled strong



 

Come to think of it i am thinking about the coating on the valves and not the seats, sorry. That was on my quad engine that they ground the valves. 
I have heard of a tuning method of people removing the main jet to dial in the needle and slide portion of range since the needle will be doing all the metering until pulled out of the tube then the main is doing all metering.
mains are 120

Try to find the Mikuni round slide carb tuning manual online I suggest downloading a copy for reference.

I believe they suggest tuning the main jet for best performance before looking at the other circuits.

A stock main for CB750 is a 105 Keihin which is about the same size as a 102 Mikuni. Your running pod filters and a 4 into 2 exhaust which would put you 6 jet sizes over stock so according to the info I have that puts you in the 108 to 110 main jet range.

Have you tried other main jets other than the 120's?

There is a simple way to check if your main is the correct size by applying the choke lever in top gear at highway speed.

My mistake, it has 125 mains. Even more fuel. I did not try pulling choke under wot. I haven't had a chance to get on the hwy very long until I get idle sorted. I will get some mains in that area of 108 to 115 and go from there.
Just gotta say... I really mean it when I say THANKS to everyone reading this and all the responses of years of knowledge coming together 

I believe your just rich on the main jet which is not a big deal especially after a rebuild. Would be better to be rich than lean during break in.

If your at 125 on the main I would drop down to 115 and see what that does for you. Swap out those old plug for new ones or burn the carbon off them with a propane torch. You still need to do a plug chop with new plugs, and I would still suggest setting the pilot jet with a ColorTune kit.

I recently went thru this on a build of my own, chasing pilot jet and choke plungers to find out the main was too big to start off with. This was on a 750 engine with larger carbs than stock. Fluffy black plug same as you, backed off on the main jet 3 sizes until the plugs burned tan color. My pilot jet was set with ColorTune kit and had to be adjusted after dropping down the main jet. Just a overly rich jet selection which can be frustrating as you need to check all the tuning factors that affect combustion.

I'm on it. I will probably just order a few sizes around the 115 mark. The needle clips were in #3 so that's a good start for now.
thanks for the info again!
I will keep ya'll posted

I ordered n100.604 117.5 and 110. The head of the jets are larger than the ones already in it but they have same size threads so I put the 117.5 and it didn't make any difference. Still sputters just off idle around ⅛ throttle. Anything higher it clears up and goes