Exhaust sucking air

We just completed 883 converstion, and i think we got a problem.With the bike running i put my hand over the exhaust.The front exhaust will push hand away the rear will will suck hand to the pipe.It doesn,t sound quite right ether.How do i explain this,It seems to have a louder note,not constant but you can really feel it.
A little more info on the bike.We also installed new cams.The bike starts great,but she has a little slow speed blubbering.Throtlle response is smooth and quick and idles farelly well except that extra pop comeing out off the rear pipe.(Am i paranoid or is something wrong)

The difference in exhaust pulses @ your hand front/rear @ idle is normal & it's due the "odd-fire" nature of a 45-degree V-Twin engine. I can explain why, but to be of more help I'd need to know the year model of the bike & which cams you installed.

She's a 1998 with n2 cams and cv carb kit.

Stock 883 heads?

Yep,We did use your suggestions on ring gaps etc.Bike runs reallly well.

OK, now I can be of more help - I remembered your name & that you were planning an 883>1200 conversion a while back, but not the details. Don't know which pistons you chose, but for stock 883 heads, KB "reverse dome" pistons retain the stock 9:1 mechanical compression ratio (CR) & Wiseco's are available in 3 versions, 8.5:1, 9.5:1 & 10:1.

N2 cams raise the effective CR - i.e. cylinder pressure, although they don't increase the mechanical CR. Your bike came with the "D" cams, which have a symetrical pattern intake/exhaust & almost no "overlap". N2's open the intake valve sooner, but also close it sooner & the exhaust timing is different too. In previous posts I've really gotten into cam lift, duration, timing so I won't do it again here, but the point is compression can't build until the intake valve has closed & when you close it sooner, the actual cylinder pressure you get will be higher.

That makes the engine act like it's got a higher mechanical CR than it actually does & with the higher CR pistons Wiseco makes for 883>1200 conversions + N2 cams, "pinging" is a known problem. Your bike came from the factory with the ignition timing a bit more advanced than it should be & that adds to the problem. Going too rich on the carb setup will drown it & that's what so many (especially H-D dealers) do.

But let's fix the problem instead. Definitely check all intake & exhaust joints/seals & replace if you even think they are bad. The SE exhaust gaskets are far superior to the stock ones. Back the ignition timing off 2-4 degrees. Your baseline carb setup is 42 slow, 175 main, N65C needle & 2.5 turns out on the idle mixture screw. Let us know how it goes.

Great info,
She does have ping when you first take off,then you don't hear it again as you accelerate.The jets are 45-180 i'll step'em down tomorrow and test runner.I'll get back with you on it's progress.
Thank you for the help