Nikki carb runs real lean engine runs rough pops and backfire wont idle put a carb kit still sounds awful

Sounds like you have an air leak and all the air/gas going into the engine is not going thru the carb. Remove the carb and re-check everything. Hope this helps.
Here's a YouTube rebuild video.


Clean And Repair Nikki Carburetors on Intek Engines

it sounds like its starving for fuel, when it runs lean you will get backfires and if its running rough then it may be starving for fuel at idle. Try adjusting you mixture screw and see it the engine will smoot out. Your carb my be dirty and not allowing enough fuel through it.

Sounds most likely an intake leak.

With engine at idle, spray a little carb cleaner around where that carb bolts to the manifold, and where the manifold attaches to the 2 cylinder heads.

If the idle speed picks up, there's your leak.

The intake rubber seals rot over time, start to crack, and allow air to enter, leaning out your carb mixture.

any blocks in fuel system, are vacuum pipes from carb to tank ok

sounds like cam or timing chain is wore out

That is a car not a motorbike. Bikes only have 2 wheels. But you may want to set up the cam and ignition timing. it is only timing that will cause backfires.

For this types of problem,there are few help inks to troubleshoot the problem.Click the link below to go through the troubleshooting procedure to resolve the issues :----Idles rough and quits when gas pedal is pressed less? http://technoanswers.blogspot.in/2012/01/1999-ford-f-150-idles-rough-and-quits.html-----------van idles rough? http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
--------------runs lean and idles rough? http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------Car still runs Rough after tune up? http://howtobyme.blogspot.com/2011/12/car-still-runs-rough-after-tune-up.html
------------Idle flair is noticed on car? Rough idle? car will not idle? Erratic idle speed? http://technoanswers.blogspot.in/2012/02/idle-flair-is-noticed-on-car-rough-idle.html
----------High rpm in neutral? Inconsistant high RPM in neutral? http://technoanswers.blogspot.in/2012/02/high-rpm-in-neutral-inconsistant-high.html
------------Engine Backfires? http://technoanswers.blogspot.in/2012/02/jeep-backfires.html----------- Nissan stalls and bucks on Acceleration?

http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

-----------
Nissan Pathfinder Backfires? http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-backfires.html
---------How to adjust rpm? http://schematicsdiagram.blogspot.com/2011/12/how-to-adjust-rpm-on-2009-dodge-charger.html
------------Engine cuts out at 3000 RPM? http://schematicsdiagram.blogspot.com/2011/12/engine-cuts-out-at-3000-rpm.html
----------This will help.Thanks.

This sounds like the typical lean mixture problem. In order to pass the EPA's emission requirements, Harley has to jet the carb extremely lean. This causes the engine "spit" through the carb, not idle well, and run hot. To solve this problem, you need to rejet the carb by going one or two steps richer on the low speed jet and raise the slide needle slightly. If this is something that has just started recently, it could be a small bit of trash partially blocking the low speed jet in the carb or your using a different formulation of fuel. You carb probably came with a #45 slow jet. I usually install either a #48 or in some cases,a #50 depending on the exhaust system on the bike. I remove the needle from the slide and install a 3mm flat washer under the stop on the needle to RAISE the needle approximately 0.023". This enrichens the mid-range of the carb just slightly. Of course, you need to carefully drill and remove the "anti-tamper" plug from the idle mixture adjustment screw and readjust the idle mixture once you get the engine back running.

Good Luck
Steve

This sounds like the float inside the carberater bowl is not seating properly and allowing to much fuel in when the engine is running until it floods the sparkplug with fuel and causes the engine to quit. The kit to rebuild the carb is only around $15.00 thru NAPA or other auto parts or small engine stores. Hope This Helps Don

It sounds like it is running really hot. Did you check the air filter and oil level. If not these it could be the muffler.