HMF 300ex with no box lid

[2001300exguy]

I have an hmf slip on on my 300 and when i take the air box lid off it has less power and bogs down. could this be a jet issue

[rollie]

yep....gotta increase the size of the jet:)

[wcbomb]

my 03' 300ex has a full fmf p-4 with k&n run stock pilot , neddle down to 3rd pos. and a 128 keihen main runs excellent without lid, alot slower with lid. rich all-around.