Motorcycle Repair: bike wont run smooth at constant low rpms, hydraulic lifters, intermediate jet

Question
yes the bike has always done this if you apply any throttle at all it goes away, it came with an s&s g carb and it has short open exhaust on it, has hydraulic lifters in it.-------------------------
Followup To
Question -
i have an after market 120 ci evo motor with about 700 miles on it and at lower engine speeds the motor surges. feels like that it hits a few times then kinda dies and then picks up again.  when i read the plugs it seemed that i was running lean so put a larger intermediate jet in and now think i am running alittle rich but still have same problem. have also changed the timing to within specs from manufacter and still have same problem.  really feel this is a carb problem but not sure.  i have a hi-4 ignition set on race only (no voes switch),and cam is .625 in and .580 ex with 264/268 duration.  other then the stumbling at low speeds the bike runs great and very fast.
Answer -
A couple of questions. Has the bike always done this or is this somthing new? What carb are you running and what pipes? Do you solid lifters or hydrolic?
Mike

Answer
Your problem is a combination of the short exhaust and the high lift cam with the long duration. You dont have enough back pressure on the exhaust and the high lift cam is staying open to long. You can first try putting some baffles in the exhaust. They will still be loud, but will add the needed back pressure. If that doesnt work then you will probably have to go to a tuned exhaust to solve the problem.
Good luck and happy riding
Mike