36 RS Mikunis , newly built engine

Hello , I have a newly built engine , 1075cc , 12.5 : 1 . Ported head . 37.5 intake , 31 exhaust valves. Andrews 3x cams. New Kerker with no Baffle. Accel coils & wires . Dyna ignition.
Seems have to choke the carbs for minute or so then smooths out til get around 4k rpm then engine wants to pop and seems it doesn't want to take the gas . Any ideas. ? I have litterally about 10 minutes running this engine. Running 112 octane fuel .

Those are big carbs for a 1075, it could have a weak vacuum signal at low RPM. whats your jetting?

Hello , thanks for your reply . I'm sure it's the jets that the carbs came with . I had pretty much the same engine built in 93 and had the Mikuni 36 on it. It ran perfect , turn the throttle and go . I don't think my engine builder did anything to these carbs. I Dont think he synced them.. Said something about being new carbs and he already did a vacuum check , it should be good . Engine doesn't want to run too good above 4k rpm.. seems doesn't want to take the gas. .

raise needle up 1 position and see how it does.

what ignition are you running? could be an advance problem

I'm not much of a carb guy but my engine builder seems to be very knowledgeable . I'm going to let him see what adjustments he thinks needs done . Thanks for your input , that may be the problem .