NEW K&N air filter problem

[dunerunner25]

Hey my 83' ATC 70 was running great then I put a new k&n air filter on from beatrice. Its poping again!! It runs better if the choke is on. I turned in the air/fuel mix screw all the way in and it helped a little but I am bottomed out on the screw and it is still not wright. I guess the engine is getting too much air from the mod. Does any one know what jet I need to fix the problem or how??

[ATCnut]

You need to rejet

[dunerunner25]

Do you know what size is stock 70 main jet is?(My guess is 76??) And is there any one out there running the same set up with a K&N?? What size jet should I order?? each main jet is $3.50 so exact would help a bunch.

[dunerunner25]

Kasey,
You seem knowledgeable...do you know what jet I should try first?? I would like to get it running tonight. Shops around my house arn't much help. Thanks....
I have seen a trike on beatrice and also glamisdunes.com called ESCO running a K&N.(blue and black ATC 70) Is he on this site and if so what main jet is he running??

[TravEX]

Stock is a 58. I have stock exhaust on 1 of mine and the clamp-on filter, and I'm running a 64 main,and it's good. The jet sizes jump from 64 to 68, so I went with the 64. My other 70 has stock air box and I put a 60 in it. I had to richen both of em up when I got em.