Dead on top.

[Junkyshee]

Ok so I haven't touched my shee in a week or so been waiting on my TORS delete kit and carb rebuild kits. Well got everything together earlier and it starts and runs SO much better, sounds way cleaner than it has since I got it together. Still running stock pipes, .60 over (supposedly), k&n filter but I forgot the lid at my shop so I wasn't running a lid. So I run the air screws two rounds out, fired it right up let it warm up, adjusted idle and took it down the road. Revs excellent, but when I took it down the road anything over 1/4 throttle was complete bog, like fall on its face like it was running out of gas. I run the air screws half a round in and took it back out and it ran great until half throttle, and once again it would just bog completely out until I came back to under half throttle. Finally for shits and gigs I ran the air screw all the way in just to see, took it out and it runs awesome until 3/4 throttle or just a hair over. Would my air box lid make that big of a difference not having it on? Stock jets, 75ish degrees and in central Kentucky not sure on elevation. Any help will be appreciated. Thanks in advance guys. (Also completely forgot to check my plugs I was in a rush and it sounds like a lean issue, so didn't think to check them)

[RadarRacing]

The lid makes a little power difference in your case but mostly just a huge difference in the amount of vacuum which draws fuel thru the carb jets.

[SpecialEd 05]

Yes the airbox lid does make a noticeable difference. I used to run a modified lid with vents on 280 main jets. Went great. One weekend I took the lid off just to see and it was a lot flatter on the top. Noticeabley different. I started thinking my engine was on its way out so I got my buddy to ride it to see what he thought. We ended up putting the lid back on and it was back pulling hard again. As far as jetting goes mods like snorkel removal are worth an extra 2 jet sizes and the lid removal is another 2 jet sizes at least.