Removed Air Box

[CafeRS]

I have an 81RS, I took the air box and pollution control items off yesterday. I plugged the heads, but what do I do about the crankcase breather (?) that leads to the airbox? Is it a breather? Do I plug that? If not, what do I do?

Thanks for your help.

First bike.......rookie here.

[StanOBMW]

Run a hose into any catch bottle of some kind. I've seen racers use all kinds of cool containers as catch bottles: empty PBR cans, fake nitrous bottles, empty plastic oil containers. You can make it conspicuous (attach to the frame in plain sight) or hide it somewhat for a more streamlined look. I have an empty oil container hidden up under my racing seat.

[Garnet]

And make sure your catch tank had some holes in the top so it can breath.

[StanOBMW]

Good point. The purpose of a breather is to actually breathe.

[vanzen]

Understand that StanO's scenario is tried and true – works well on a track machine that favors high rpm tuning.

Removing the air-box and the resulting loss of intake volume
WILL compromise torque delivery at low to mid rpms,
i.e. the bike's tractability on the street and in traffic will suffer.
What works best on the track does not always translate so well to the street !

The best street machines will tune for the fattest & flattest torque delivery through mid rpms –
and not max HP near or past redline as a track bike.
Put the power where you will be using it most.

Do not expect any high rpm performance gains by removing the air-box
without appropriate changes to the rest of the "system" –

A "catch can" is required on the track to keep oil off the track
and perhaps a good idea for the environmentally conscious street poser,
but the old school method just had the breather hose running off the back of the bike,
and oil vapor was scattered to the wind.

Just saying ...

[Deleted User 287]

Old school, here.

These are old pictures. I have reconfigured it a little bit, but it is basically the same:

[Garnet]

Understand that StanO's scenario is tried and true – works well on a track machine that favors high rpm tuning.

Removing the air-box and the resulting loss of intake volume
WILL compromise torque delivery at low to mid rpms,
i.e. the bike's tractability on the street and in traffic will suffer.
What works best on the track does not always translate so well to the street !

The best street machines will tune for the fattest & flattest torque delivery through mid rpms –
and not max HP near or past redline as a track bike.
Put the power where you will be using it most.
...

I agree.

I have two R75/5 engines, one in a /2 converion seen here:


and one stock /5.

I have swaped the carbs from one bike to the other and have to run slightly richer settings with the stock airbox than I do with the pod filters. In other words the little racing filters on the above picture are MORE restrictive than the stock clam shell airbox.