Airbox modding

[lloydie]

Just wondering has any tried an open top air box with a standard air filter .
I know some have tried it with a k&n and failed myself included .

I ask because when I had the standard lid on it feels the nearly the same as the lid with the bigger snorkel .

So I'm wondering wether its the standard air filter that's restricting the air and not the snorkel .
If this is the case then you could do away with the lid and raise the filter up an inch away from the stacks thus getting more volume in the box :-)

Right I'm off back into the garage to try it ill report back :-)

[mik_str]

I had tried running an open airbox with a K&N filter. I rode it to my tech for a dyno tune (ran like crap all teh way there, was obviously very lean). He tried various runs and couldn't get it right, I decided to pull the plug ont he experiements before getting broke from dyno time.

I just cut a new lid ring with the objectve to giving it another go. My plan at this time is to wait until I get the Moriwaki Stage 1 cams installed (bought a used set from a superhawkfoum member and they are currently sitting in a box, will wait until next valve adjustement to have them installed; currently have OEM cams in). I have a spare set of carbs that I hope to get close to the final settings (with advice from Roger) so I can get it close before brnging it to dyno for fine tuning (my time costs me nothing, unlike dyno time)......

[lloydie]

It works and works well a little rich in the mid range lower the needle a little i think .


[youtube][/youtube]
the throttle is much more responsive and snappier oh and the sound .
i took it down the local dual carriageway and opened it up and it pulls hard right from 2.5k to 9k and its good through the 30mph streets to .
next step is to make a big ass spacer to raise the filter up

current carb settings and parts running are
front carb
Standard mains 48s slow
1 slide lift hole slied
1.5 turns out mixture
standard needle with 1 washers

rear carb
Standard mains 48s slow
2 slide lift holes
1.75 turns out mixture
standard needle 2 washer

standard air filter
standard exhausts (debaffled )
+4 ignition advancer
stick coils
gutted airbox bottom with filter ring .

[8541Hawk]

Well I have a couple of ideas for you guys....let me finish thinking it through and I'll post it up a little later.....

Man I need to get that shock back.......lol

[VTRDark]

Well done Lloyd and Mik, i'm loving all these airbox experiments. Mik you should have no problems with an open airbox with the HRC needle and main air block off's.

So Lloyd you have basically just removed the lid and extended the height of the box which raises the filer up to where the lid would have been. I can her the induction noise in you vid. That must cream when you pick up speed.

(:-})

[lloydie]

I cream when it on song :-)

I've just been having a look as to how to make a spacer to raise the standard filter and it don't look easy as the standard filter stands taller than a k&n .
More thinking needed as I want it reversible to standard

[Ckennedy]

Do you want to have a tinker with mine Lloyd? I do like the noise that think is making. I do have a question regarding mine which could be related to the air box but I am unsure. When I am pottering along and whack the throttle open the bike hesitates a little before before picking up. Any ideas?

[lloydie]

Do you want to have a tinker with mine Lloyd? I do like the noise that think is making. I do have a question regarding mine which could be related to the air box but I am unsure. When I am pottering along and whack the throttle open the bike hesitates a little before before picking up. Any ideas?

sink your carbs
lets see how it does on the dyno

[Ckennedy]

Need to get my hands on the stuff to do that then.

Be nice if I could have made it to the dyno day. Don't think I'm able to

[8541Hawk]

It works and works well a little rich in the mid range lower the needle a little i think .

What RPM range is this happening?

Might be another spot where the airflow is acting up and causing a stall..... so I'm just trying to keep track of where they happen.

[lloydie]

3-5k just felt a little fluffy compared to the rest thats why im thinking its the needles that need lowering a tad .
the dyno should show it .
i now have more things that i can afford to test now so i will have to choose

[mik_str]

I just thought of something, anohter potential airbox mod:
- take a pristine airbox lid
- cut most of flat portion of the lid, except for a 1/4" to 1/2" strip all around, do NOT cut the sides
- glue a thick, closed cell foam on the 1/2" strip, thereby creating a seal with the underside of the tank

thoughts?

I may just have to give this one a whirl.......

[8541Hawk]

I just thought of something, anohter potential airbox mod:
- take a pristine airbox lid
- cut most of flat portion of the lid, except for a 1/4" to 1/2" strip all around, do NOT cut the sides
- glue a thick, closed cell foam on the 1/2" strip, thereby creating a seal with the underside of the tank

thoughts?

I may just have to give this one a whirl.......

That would give you the most volume available, so why not give it a whirl......

[mik_str]

oh sure, encourage me... lol

the quest for a lid begins........

[8541Hawk]

As tomorrow will be 6 weeks without a bike, I've had just a little too much time to sit and think lately.....lol

So here is what I have been looking at in regards to the airbox.
I guess I should give a little background so you guys can have a better understanding of how I look at this set of problems.

In real life, when I'm not playing with motorbikes....lol
I'm a vacuum tech, no not a rug sucker but space simulation chambers and helium mass spectrometers.
It's the reason why CV carbs are not really a mystery to me.....lol

With that the stock box is actually pretty good and has a couple of kind of trick features IMHO.

So this is how I see the stock box and what I plan on messing with, though it is still theory for me as I haven't done any of it yet.

Starting at the front, the snorkel looks pretty good and while I have seen the center bit cut out, I'm not sure that is the best way. In my thinking that bit might be there as a vane to straighten out the air flow or stop a circular vortex from forming in the snorkel. Right now I am looking to see if there is any way to make it a bit wider while keeping the center vane but don't know if that will be possible.

Then there is the top, with that baffle that some folks wonder why it is there and I have seen a mod to remove it but personally I feel the bike runs better with it in there.
The way I see the upper section of the box is a simple venturi though it could also be called an orifice plate...in any case what it does is by the smaller front section volume feeding the larger rear section past the plate is causing the air flow to smooth out and helps it become "calm" which is what CV carbs want.

From here, things seem to go a little down hill.

First there is the issue that it is not really good to point the stacks directly at the filter but there isn't room for anything else and then there is all the other "stuff" that ended up in the box.

Removing all the unnecessary bits has been well covered and while Micky's latest adventure looks interesting, I'm not sure how much it will help with the sharp corners.

So spacing the filter up looks like the best route and where I have had another idea.

Once again I don't have numbers to work with as I haven't done it yet but I was thinking what would happen if you spaced the filter up say 15-20mm.
Then take a flat plate of Al or even plastic that is slightly larger than the filter itself or possibly a strip slightly wider than the bell-mouths of the stacks.
Find a set of stand offs the size that you raised the filter and mount the plate under the filter.

This might stop the issues of the air feeding directly into the stacks or it could frak things up good..... not sure but just a thought.

The other thing that might be helpful while doing these types of mods\experiments is a second flo-commander on the pilot circuit.
Also I would advise running their small filter on both of them as this smooths out the flow that little bit more and why not go full Monty for a couple $$ more.


That's all for right now..... sorry to ramble on so.....lol