Not the best of ideas, you really need a filter, it only takes one trip into the kitty litter for the engine to ingest gravel or any other foreign object to play havoc with your engine internals. Remove the lid, but leave a performance air filter in place.

Did a dyno run a few years ago on a 583 class B, very little gain in hp, less than 1bhp.

If weight saving is your main aim, look at other items, the battery is the biggest area to lose weight, trim the frame of excess bits, make sure your fairing is as light as it can be etc.


Chris:burn:

agree - some filter is needed and helped witrh power rather than reduce on my 583...not sure of difference on a 620 as didnt try it. But dyno man tried with pods v with airbox and set up with pods would have been much harder he said

ran my 800 for a year in minitwins with no filter

back to back dyno runs showed a 4 - 5 horse increase all through the curve without one

had a good classics set up in the w100 club .. always liked the look and sound of the open carbs

admitedly i'd be a little nervous just having the throttle bodies open to the atmosphere at least the airbox affords some protection

Did you have different maps done for both, or was it a case of adding the filter richened the mixture and lost 4 - 5 bhp

had a custom map for both

I fitted some of these to my 900ss engined Monster:

http://www.unifilter.com/online%20ca...universal.html

Got a nice induction roar as a pro!!

Yorkie

looks just the ticket

hmmmm ... what about a couple of small air scoops with an in line filter?

I think AK tried ram air several years ago without any real success.
As my 620 uses the same size airbox, throttle bodies and injectors as my 1000SS I doubt there is much that is holding back the performance once the airbox lid is opened up.

As Andy Pike says a Plenum chamber is one of the best ways to go so as to create a large reservoir of still air for the engine to be able to draw on, so long as that air can be replaced as quickly if not quicker than the engine uses it then it should be able provide the desired air/fuel ratio through out the rev range and not be effected by speed

ah but it's not just performance kev .. it's the joy of creating something different .. and something you can blame when your slower than everyone else :lol:

does the airbox create a reservoir of still air? ..after all it's being constantly drawn

i can imagine with the trumpets in place you could expect the incoming air to be sucked in in a nice laminar fashion .. but with the top hacked off??