Once it's all cleaned out there should be no dramas with surging. Mine's got a full V&H and runs sweetly through town at 2k, nice and quiet. It sounds like gum and other crap in the carbs to me.

These bikes are smooth!

 

I have a kerker 4to1 and a K&N filter with 125 main. I have a bit of surge while trying to maintain steady speed below 3K. It is hardly noticeable, but I feel it and I get some backfiring when slowing down from high RPMs. I have thought of rejetting and going back to stock exhaust, but funds arent avail yet. I was wondering how these bikes respond with stock jets on my kind of set up.

 

hmm run 4k on up and it won't "lug" on ya

 

What you described is common for a bike with carbs that are out of balance. Weather it be clogged carbs or out of sync, they are fighting each other and causing surge.

As mentioned, running some carb cleaner may help but you may still need to sync the carbs.

If the carbs were not synced after the 4-1 was installed, you definitely need to sync the carbs.

 

I have them bench synced, but thats it. When I get my hands on a balancer, I will give it a shot. Carbs are clean as a whistle, so for now I will just deal with it. Believe me its not bad. Also does anyone run stock jets on this set up? or do the rejet? thanks