I would go down on the pilot 1 or 2 sizes at a time and see how it runs.don't make a lot of adjustments all at once. then check the plug again and make sure you use new plugs to get an accurate reading.ngk iridium are what we always used.you can also screw the air/fuel screw OUT to lean it a little bit and see if there's any change and if there is then you're headed in the right direction. you're also going to have to do a full throttle run to check the main too.don't do it on stands as it's going to need a load on it.also,have you checked the torque spring?? checked and cleaned the belt ??
I haven't checked the torque spring or the belt.... So, stupid me,I changed the needle position and then messed with the air/fuel mixture and got it cranking, thought I was done.... then noticed the damn choke was on... turned off the choke and leaned it all the way out and couldn't get it to run right at all. Does this confirm the need for the jet?
Another question, would I just switch out the pilot or the main jet as well? I was under the impression the pilot just covered the bottom 1/8 of the carb. Sorry for the probably simple question, just trying to learn something here as well.
That being said, I REALLY appreciate your responses to this point.
with a new plug and the choke off this time (lol) get it going and try the air fuel screw and SLOWLY lean it out (turn screw out) and see what it does. if you notice a change you have to go down on the pilot jet.the pilot controls idle to a little more than half throttle so do one thing at a time.get it to idle first then see if your bog goes away and then move on to a full throttle run and check the plug again to see what the main needs.also,a weak torque spring on the rear pulley can mess with things a little so look into that as well.for a stock 90 with no mods you can do a stock replacement or possibly go to 1,500 rear spring.we use a 1,500 rear spring in ours but it has a lot of carb/clutch and pipe work.also,looking back at your posts you said you moved the needle clip down?? I believe that's going to add fuel so you might want to move the clip up from the original spot and go from there.if I remember correctly when you move it up it lets in less fuel and moving it down uses more fuel.it has to do with the needle traveling up and down in the jet.
So then, more evidence that I'm an idiot, I have been turning the screw in to try and lean it out a that is what seemed to work with the choke in the on position. I'll try turning the other way to see if that helps, but it just seemed to give me less power as I turned it that way when the choke was on....
So... turning the screw the correct direction did help a bit but it's clear that the jets need to be changed. Once I tear it apart, I'll figure out what I need and go from there, ugh.