Im in the middle of fixing up a cbr250rr and upon pulling the airbox apart im curious about a couple things, 1) do i need the plate under the paper filter, as it is basicly two holes coverd with some mesh and 2) is there any mods or neat ways to get more cold air in there (also would it be useful). Cheers for any help
The intake (airbox and filter) , the carbs (jetting etc) , the exhaust (headers mufflers) were all designed and engineered by some pretty smart little Japanese men back then ,so the bike ran well and efficiently and all those things worked together. Changing those dynamics can be positive or negative Also remember that its not just the filter, but the shape and size etc of the airbox that affects the airflow.
1) That plate you refer to, with the mesh and the two holes is to assist with backfiring I believe. 2) You probably don't need to modify the airbox as per say. But for racing, I removed the air filter together and left the mesh bit in there (not the best idea and crap did go in the carby) but she breathed a lot better with bigger jetting. So, if you are going an aftermarket exhaust, slightly bigger jetting, then I would certainly look at using a stock air filter (cut the inners out of it and replace it with some smaller foam) to assist in better breathing and air flow.
in regards to the headers @kiffsta was telling what happened with a racer.. he can fill you in on the rest...
