I did a couple of back to back dyno runs with and without an undertank over bell mouth filters. Bike gained 10 hp without filter (and it was clean) at top end, gains started from 4000 rpm, no loss anywhere. Now use ITG
Some people just like spending money for the sake of it, the pipercross filters that replace the stock filters are less than £20 and don't seem to have any disadvantages, I read shazaam's post on the subject.
If I was selling and fitting parts I might suggest the more expensive option too.
Mood: R U thinking what I'm thinking?......Oh dear!
The mesh acts as primary filter stoping big bits getting to whatever air filter you have fitted. When modifying the mesh you might find the air fuel ratio needs some adjustment, but that depends variables such as what type of air filter you are using.
Generally speaking if you get more air into the engine you need more fuel to go with it to get a benefit. All depends where you are when you start, e.g. OK, lean or rich, even then some spooky stuff can happen, i.e. the opposite of what you might expect. e.g. on my bike I expected it to be rich because of an air restriction in the way of the front cylinder bellmouth but when tested it was lean.
Maybe because these bikes don't have any sorted of MAF sensor or lambda sensor controlled trim? Would be interested to know what determines the amount of fuel the injectors are "told" to throw in? TPS, water temp (below a cetain threashold?), engine RPM?? Not very sophisticated compared to a modern 4 wheeler??
The air/fuel ratio can vary between the front and rear cylinder, the air filter set up can influence this as well.
With the changes made to my bike the next move would be a power commander, or an FIM ECU to set the fueling as near to the ideal for each cylinder as possible.
Thanks to all who replied. After much deliberation i'm going for a pipercross as it's cheapest, seems to be about the "best" for my modest requirements and by all accounts should sound lovely-jubbly too!
alright dudes?! i've been looking at shazaams post, he recommends mpxo38's but on the web site pipercross only mention mpx068's? ahhhhh I hate decisions!!
I've been running MPX038s for nearly two years now on the 748. I got mine from Demon Tweeks, and they were £19 for the pair!
They fit lovely into my carbon air tubes which have the runners for the oem filters, but I found it better if you (carefully) take the plastic cage off the oem filters and use these on the pipercross ones to help maintain their shape.