my banshee is jetted 270 im running stock exhaust .20 bore and a k&n filter is that high of a jet doing more harm then good

 

Yeah, your running a bit rich.... It's not going to do any damage... Except for maybe fouled spark plugs....The bike will make less power when you are to rich...

 

I think my cousin's fmf fatty piped shee is running a 260 or so and it hasnt blown up yet. I think you are way rich, but I know he doesnt know how to jet his machine so he's probably off too.

 

270 for a stock banshee (other than the air filter) is WAY rich. I run a 270 on mine with the mods I have and am thinking of leaning it out even more. I'd think you would need a 220 or something along that line...OR, you could just buy a set of pipes and be set. Elevation has a role in how your jetting should be, but not THAT much...

I would think if you're running it with that fat of a main it would run like absolute crap though. My banshee ran horrible when I had a 290 in it; which is only 2 sizes bigger than what I run now. If it doesn't spit and sputter like it is now I would check the carb boots for an air leak....

 

I have a lot into my shee and I run 260's in the summer 280's right now and I will throw 300's in for like -20 weather