David Jenkins
|
| posted on 12/4/08 at 03:28 PM |
|
|
Decision: mock-sausage or airbox!
I'm still struggling to fit an air filter without cutting the bonnet...
I have made a suitable backplate, and realised that I can now make a choice:
1. I can put filter foam across the front to make a sawn-off sausage filter - this is easy, I have the materials, and I could finish it tomorrow. It
will have a very large area of filter. The down-side is that the face will be fairly close to the bonnet line at one end, although there will be a
decent draft from a bonnet air scoop (once I build a diverter). I would also make some air-holes nearby.
2. I can put a solid sheet across the front and make it an airbox. The downside there is that the inlet tube can be no larger than 50mm diameter, and
my radiator is a snug fit in the nose cone, so a remote air filter will have to be in the engine compartment somewhere.
My feeling is that it should be option 1 due to the small size of the airbox inlet hose.
Any other views?
David
|
|
|
|
|
David Jenkins
|
| posted on 12/4/08 at 05:40 PM |
|
|
Coo... quiet round 'ere...
|
|
|
iank
|
| posted on 12/4/08 at 05:58 PM |
|
|
Sounds like 1 would be the way to go. Presume you could mod it to version 2 later if it doesn't work out.
Maybe a photo of some cardboard mockups would help?
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
|
|
|
jacko
|
| posted on 12/4/08 at 06:15 PM |
|
|
I don't know if this will help but if you look in my archives under zx9r carbs you will see how i made my a/ box .
you could put a pipe in the rear end for a filter
Jacko
|
|
|
David Jenkins
|
| posted on 12/4/08 at 06:54 PM |
|
|
quote:
Originally posted by iank
Maybe a photo of some cardboard mockups would help?
Never mind the cardboard mock-up - here's the aluminium version! 
If I do option 1 then the whole of the front face will be filter foam. In this case I'll put a row of air holes along the bonnet just above the
chassis line.
If I do option 2 then the front will be a sheet of ali and there would be a 50mm duct forward somewhere.
|
|
|
indykid
|
| posted on 12/4/08 at 07:32 PM |
|
|
aesthetically, an airbox would look better imho, but idea 1 would probably be easier to execute.
would a 50mm inlet be sufficient?
tom
|
|
|
iank
|
| posted on 12/4/08 at 07:48 PM |
|
|
So long as the foam in option 1 has a sturdy mesh behind it I think it'll be fine. If not it will collapse down onto the trumpets and bork the
airflow.
[Edited on 12/4/08 by iank]
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
|
|
|
02GF74
|
| posted on 12/4/08 at 08:10 PM |
|
|
option 3. cut a hole in the bonnet.
judging by your backplate, the outer surface of the filter would be almost touching the bonnet so that isn't going to help air flow.
also rule of thumb the filter element shold be at least the diameter of the carb bore away from the trumpet mouth - yours look like they will be on
the limit.
you will need to mess about with ducts for cold air too.
Loads of people have bonnets with holes, only small disadvantage is it makes it slight harder to fit the bonnet but hey, hom many times a day you need
to do that?
not the anser you wanted but ..... 
|
|
|
zilspeed
|
| posted on 12/4/08 at 08:30 PM |
|
|
Vote for a proper airbox with a forward facing intake, sounds way better to those fortunate enough to be standing in front of it as it approaches.
I know that's possibly not important, but there you go.
Like this.
[Edited on 12/4/08 by zilspeed]
|
|
|
David Jenkins
|
| posted on 12/4/08 at 09:37 PM |
|
|
Originally posted by 02GF74
> option 3. cut a hole in the bonnet.
I've already got a scoop - too many strange holes would look silly!
>judging by your backplate, the outer surface of the filter would be almost touching the bonnet so that isn't going to help air flow.
Only at the very front edge - the rest will be quite a way from the bonnet.
>also rule of thumb the filter element shold be at least the diameter of the carb bore away from the trumpet mouth - yours look like they will be
on the limit.
The filter will be further away than it looks - about 50mm.
> you will need to mess about with ducts for cold air too.
Not too much - the existing bonnet vent just needs a plate to shift the air in the right direction (it's nearly over where the filter will
go)
> not the anser you wanted but .....
I'll take all opinions on board - then I'll do what I want!
|
|
|
David Jenkins
|
| posted on 12/4/08 at 09:39 PM |
|
|
quote:
Originally posted by zilspeed
Vote for a proper airbox with a forward facing intake, sounds way better to those fortunate enough to be standing in front of it as it approaches.
I know that's possibly not important, but there you go.
Like this.
That won't fit without major surgery! And there's nowhere for the ducting to go, as the rad is too tight a fit in the nose.
|
|
|
907
|
| posted on 12/4/08 at 09:45 PM |
|
|
Hi David.
Could the inlet to an air box be oval?
A 50 x 100mm oval would = 75 dia. (ish)
Paul G
|
|
|
Jon Ison
|
| posted on 12/4/08 at 09:45 PM |
|
|
Dave, you may be surprised how well your "mock up" could work, its not a million miles from mine looking at the pic, if you had the top
covered and the filtration down by the chassis rail then it would be almost identical, will take a pic for you tomorrow.
We tried one or two options on the rolling road and the one that looks like your "mock up" is still on, it works, must be some sort of
impulses generated of the close-ish top (that you don't have on yet) that does the trick.
not explaining my self very well in words i know, I'm calling the top the bit that would be on top if the bellmouths where straight up 90* I
know, clear as mud.
|
|
|
Jon Ison
|
| posted on 12/4/08 at 09:51 PM |
|
|
bit like this, the red area on mine is a solid ally top with air entering through the side in direction of arrows via a paper filter. I know the
trumpets may look close to the lid but it makes genuine bhp on mine set up like this proven back to back on the rolling road, helps with the noise
too.
 
Rescued attachment filter-base-s.jpg
|
|
|
David Jenkins
|
| posted on 13/4/08 at 08:32 PM |
|
|
Paul - I thought about an oval, but I'm trying to avoid welding (and that's not a hint!), plus I really don't have anywhere to take
the conduit to, apart from behind the radiator. I'm not sure how squashable air duct is either - it's reinforced, isn't it?
Jon - covering the top 3/4 and put a filter near the bottom was option 3! I'm not too worried about noise (I like the induction roar ) and I
don't have track marshals to pacify.
I'll make my mind up over the next few evenings, as I work out the final details.
cheers to all,
David
|
|
|
907
|
| posted on 14/4/08 at 09:54 AM |
|
|
quote:
Originally posted by David Jenkins
Paul - I thought about an oval, but I'm trying to avoid welding (and that's not a hint!), plus I really don't have anywhere to take the
conduit to, apart from behind the radiator. I'm not sure how squashable air duct is either - it's reinforced, isn't it?
Jon - covering the top 3/4 and put a filter near the bottom was option 3! I'm not too worried about noise (I like the induction roar ) and I
don't have track marshals to pacify.
I'll make my mind up over the next few evenings, as I work out the final details.
cheers to all,
David
Hi David.
Avoiding welding is my speciality. 
The pic below shows a trim flange I made to go round a hole in a grill where an exhaust passed through.
(no doubt it will be recognized by someone )
I made it by folding a 10mm lip on a flat strip of ally, then pulling it round a piece of pipe by hand.
If the ends were overlapped it could be pop riveted together.
Slipped through a suitable matching hole the 10mm flange could again be pop riveted in place.
Flexi air duct has a spring steel wire in it and can be squashed to any shape.
This sort of trim piece is easy to make and could well be of use to others who may wish to trim bonnet holes etc.
As you can tell I'm sitting at home with nothing to do ( nursing my poor sore paw ) wishing I could do something useful. 
ATB
Paul G
 
Rescued attachment Ally-Flange-s.jpg
|
|
|
David Jenkins
|
| posted on 23/4/08 at 07:50 PM |
|
|
Well, this is what I ended up with...
There will be a slight design compromise - I will be cutting some holes at the bottom of the bonnet side, to let in fresh air.
The foam is proper Pipercross stuff, with proper filter oil on it, and it's backed up with reasonably strong but very open-weave aluminium
mesh.
I thought that this was going to be the last job with fitting these carbs, but since mounting this filter box I've found that I can't
reach the idle screw without burning my hand - I'll have to make a simple bracket for the original bike's remote idle screw. Easy enough,
but yet another job to do. Sigh...
|
|
|
rusty nuts
|
| posted on 23/4/08 at 07:53 PM |
|
|
Wimp , I have to slave over hot engines all day and I've got the scars to prove it.
|
|
|
02GF74
|
 posted on 24/4/08 at 08:12 AM |
|
|
good job !!
one Q. you have mesh on inside, to stop filter being sucked in, but what is there on the outside to stop it being blown outwards?
I notice that both piper cross and K&N have mesh on both sides (not talking abou the foam sock things).
|
|
|
David Jenkins
|
| posted on 24/4/08 at 08:35 AM |
|
|
The foam is reasonably snug on the inner mesh - any backfire that's powerful to tear it off is going to cause plenty of other problems!
The Pipercross PX-500 filter on my old Weber carb had just a band of mesh on the inside and nothing on the outside.
Here's the inside before I tidied it up a bit.
|
|
|
.jpg)
