OK- I am an old two stroke guy and the air screw on a two stroke carb would be leaner (more air) as you screw OUT the screw.

With that said, Installed a new set of Yosh cans, bike has a Dyno Jet Kit (largest mains installed in the kit) and I still have a K&N Filter to install. Without the new K&N the bike is a bitch to start (was with the stock cans too with the Dyno kit installed) and now with the Yoush exhaust she runs strong no hesitation anywhere but coming off of the throttle she POPs..... pop, pop, pop.

To me, that means she is a tad lean on the pilot jet OR the fuel screw needs adjustment. I spoke to DynoJet and he was telling me to take the mixture screw from 2.5 turns (Dynojet setting) to 3.5 turns. When I commented on turning out being leaner he stopped me and said NO that this is a fuel mixture screw and out is more fuel...

Again I am a two stroke guy and that seems opposite to me BUT I thought I would ask you Gurus.. The symptoms of being lean would explain the hard to start issues too?

Btw...He also told me to try and take the two hoses that run from the airbox to the heads and plug them or clamp them. He mentioned this could be the issue for the backfire as well. I really hate messing with a bike Clamping hoses) that had someone a whole lot smarter than me engineer for a reason.

Advice is greatly appreciated....

 

They are fuel screws not air bleeds so out is richer.

A K&N filter will just cause you more problems and you would be better off staying with the stock filter.

There is no need to plug the hoses to the heads, in fact that could cause a whole different set of problems.

If it pops on decel open the pilot screws 1\2 a turn.

I have also found that a stock motor really doesn't need that large of main jets, but that is another discussion.

 

The pops on decel could also just be the PAIR system doing what it is supposed to combined with an aftermarket exhaust..

Try dePAIRing it.

 

I agree with 8541Hawk. I took his advice when I got my slip-ons, and just went up one size on the pilot jets. I'd already done a needle shim. And with a stock filter, mine pulls like crazy, especially above 4000 rpm. No flat spots anywhere. To me, that means the main jets are fine.