Bell-mouth intake
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nothing at all
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Tue Feb 04, 2014 12:33 pm quote
HappyOne wrote:
Any plans for one for the ET4?
4 years old....I think you win the chicken dinner.

Try PM'n Oopsclunkthud or check his site.
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Sat Aug 13, 2016 9:30 pm quote
started working on a bell to fit the 24mm carb.

Still playing with ideas but it will not look anything like anything.
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Sat Aug 13, 2016 9:47 pm quote
intriguing... any pre-production or spy photos... mockups... 3D renderings...

signed,
-an interested party
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Sat Aug 13, 2016 10:19 pm quote
Here's the idea I'm playing with. Need to take some measurements and figure out exactly how much room I have to work with between the top of the carb and the top of the air box.

Screen Shot 2016-08-13 at 23.16.40 .png

Sergeant at Arms
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Sat Aug 13, 2016 10:34 pm quote
i like the short side radius... lots of velocity there. digging it.

T5/Stella air box top? or maybe something full custom? hydroforming and stamping is getting cheaper and cheaper. i have a few contacts here, but we'd probably have to hit a minimum...

i know you don't want to go full production, but just throwing around ideas.

and, also, i don't say it enough, but thank you for all that you do for the community. constantly pushing the envelope and designing new and innovative things for our ridiculous shopping trolly shitbox mopeds. much respect and gratitude.

-g
Ossessionato
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Sun Aug 14, 2016 5:54 am quote
No real need for the lip at the top, as the inside of the lid of the carb-box will push the air towards the neck... The lip would disrupt this effect.

I had a look for my 'vortex', but so far it remains elusive
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Sun Aug 14, 2016 9:24 am quote
at this point still just playing with ideas.

The big problem is that any smoothing of the airflow into the top of the carb reduces the space between the bell and the top of the air box.

Here's the latest "could this even work" thought.

Screen Shot 2016-08-14 at 10.17.21 .png

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
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Tue Aug 16, 2016 3:07 am quote
What if you cut a hole through the lid? The early type might be easier... you could even add a lip around the intake for the lid to sit on.

Clipboard01.jpg

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Tue Aug 16, 2016 4:53 am quote
Yup, that's what I'm thinking, but two holes in the lid of the carb box. make the bell out of rubber with lip built in on either end.
Ossessionato
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Tue Aug 16, 2016 5:43 am quote
Are you thinking of air being sucked from the frame or just from inside the panel?
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Tue Aug 16, 2016 6:37 am quote
from the frame, it's cool dry and mostly clean.

air would come from the frame, into the airbox, up into the bell (mounted in the lid of the carb box), and then straight down (passing through the carb box lid again) into the carb.

I think there may even be room to put a filter inside the lid surrounding the bell.
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Fri Aug 26, 2016 3:55 pm quote
Did some more measuring and looking at the 24 carb and noticed a small taper to the first 5mm of the carb.

There is 30mm from the top of the carb to the top of the lid. The bell should be as tall as the carb is round, so 24mm. But the carb is 24mm 5mm below the top surface, so I can lower it at least that much. After playing with it a bit I think I can make it fit and dispense with all that big looping stuff.
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Sun Aug 28, 2016 3:37 pm quote
I was thinking it would be nice to keep the rubber grommet that goes around the idle adjustment.

Came up with this

Screen Shot 2016-08-28 at 16.32.17 .png

Screen Shot 2016-08-28 at 16.38.09 .png

Molto Verboso
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Sun Aug 28, 2016 4:10 pm quote
The rubber grommet should be upside down. The narrow end houses in the air filter cover...
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Sun Aug 28, 2016 4:36 pm quote
SaFiS wrote:
The rubber grommet should be upside down. The narrow end houses in the air filter cover...
Nope, it should not, though 99.9% of the bikes have had them installed that way.
Veni, Vidi, Posti
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Sun Aug 28, 2016 7:05 pm quote
So what do you think the clearance will be from the top of the bellmouth to the lid of the carb?

I've imagined that it might be possible to make a filter that fits in behind the bellows. I'm thinking that it might clip into the body hole so that it actually sits inside, and the bellows goes on over it as per normal. I'd think 3D printing would be best for this as it could be shaped to be a good clip-in fit.
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Sun Aug 28, 2016 7:28 pm quote
Ginch wrote:
So what do you think the clearance will be from the top of the bellmouth to the lid of the carb?
12.8mm from the top of the bell to the carb box top.
Ginch wrote:
I've imagined that it might be possible to make a filter that fits in behind the bellows. I'm thinking that it might clip into the body hole so that it actually sits inside, and the bellows goes on over it as per normal. I'd think 3D printing would be best for this as it could be shaped to be a good clip-in fit.
I was looking into a similar thing today. K&N will make custom filters, not sure at what cost. was thinking of a cone shaped filter that sits inside the bellows. But I was also thinking of placing a filter at the intake under the seat.
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Sun Sep 04, 2016 9:21 am quote
I think I've found a solution for the filter. I've ordered some foam filter material and should have an example next week.

also working on a way to improve the clearance into the bell, and remove as many disruptions in the bell surface as I can. rendering later today, I think.
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Sun Sep 04, 2016 11:22 am quote
Tilted the top of the bell toward the front of the air box and away from the right wall. This reduces the amount of bell that has to be trimmed off and gives more direct access to the main direction of the airflow.

Screen Shot 2016-09-04 at 12.10.57 .png

Hooked
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Sun Sep 04, 2016 4:54 pm quote
Funny, I was just reading a Blair paper on bell optimization... so I ordered one of these for a 20/20. Hopefully it arrives before snow...
Veni, Vidi, Posti
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Sun Sep 04, 2016 7:03 pm quote
That's the one!

I'm sure tipping the bell, as I have for the 24, will make it less than ideal but then engineering is all about compromise. If I can sort out the CFD I'll do a comparison of rev a vs b and see what the better compromise is.
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Mon Sep 12, 2016 5:09 pm quote
Got the bell in the mail today. Over all the fit is good and it fits under the cover. I'll be making some small changes to it in the next rev.

IMG_1491.png

IMG_1494.png

Veni, Vidi, Posti
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Mon Sep 12, 2016 6:42 pm quote
Looks great. What's the little bump opposite the idle screw?
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Mon Sep 12, 2016 7:23 pm quote
Ginch wrote:
What's the little bump opposite the idle screw?
manufacturing requirement. I wanted to avoid having the screw come through the face of the bell on the back wall as I didn't want it in the way of the air and didn't want then chance it could back out and fall into the carb. So the bell is held in place by the spring on the idle adjustment screw and is located by two 6mm posts. Even with all that it was necessary to add a small bump to make sure the wall thickness was at least 1mm.

IMG_1489.png
M5 buttonhead screw with the OD turned down to 6mm.

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Sat Sep 17, 2016 3:10 pm quote
Here's the plan for the airfilter.

Screen Shot 2016-09-17 at 16.08.06 .png



Last edited by oopsclunkthud on Sat Sep 17, 2016 3:17 pm; edited 1 time in total
Veni, Vidi, Posti
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Sat Sep 17, 2016 3:12 pm quote
Ok... you got me. Where is it?
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Sat Sep 17, 2016 3:36 pm quote
Maybe this will help

The red is Unifilter foam. It will be glued to the black rubber carb box gasket.

Screen Shot 2016-09-17 at 16.06.01 .png

Veni, Vidi, Posti
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Sat Sep 17, 2016 4:04 pm quote
Ah! Now that is thinking inside the box!! So the air comes in under neath the foam and up into the bellmouth. Very very neat.
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Sun Sep 18, 2016 11:48 am quote
did a test fit of a paper cut out, found I had the carb position off by 2mm. This is good as it may allow the foam to go all the way around the carb.

Here's a mockup with the carb box.

off to cut out the second try.

Screen Shot 2016-09-18 at 12.43.31 .png

Veni, Vidi, Posti
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Sun Sep 18, 2016 1:24 pm quote
I wonder - now that the airflow is diffused by the filter - if it's as important to tilt the bellmouth? I guess the short circuit is still between the box opening and the carb throat.
Veni, Vidi, Posti
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Sun Sep 18, 2016 2:42 pm quote
There is more filter area hence more air in the direction it's tilted, so makes sense from that point of view if I got that right. I am liking this a LOT! Smart elegant design.
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Sun Sep 18, 2016 3:32 pm quote
Looking for someone that can laser cut the foam. me with an x-acto knife is not doing a great job, but ok for the first one.

I'm still kicking the idea around of turning this into a product, but if you want to make your own here's a PDF of the outline.

IMG_1499.png

24mmFilter.pdf
 Description:

Download
 Filename:  24mmFilter.pdf
 Filesize:  113.97 KB

Ossessionato
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Sun Sep 18, 2016 6:43 pm quote
I wonder if you want a plastic or metal mesh (coarse or just a frame) to glue that foam to so it holds shape.
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Sun Sep 18, 2016 7:32 pm quote
I've ordered some metal mesh that I'm thinking of welding into the lid but not sure it's needed. I've glued the foam to the rubber with pliobond (recommendation of Uni) and it looks like it's bonding really well.
Mr. Clean
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Sun Sep 18, 2016 7:44 pm quote
oopsclunkthud wrote:
Got the bell in the mail today. Over all the fit is good and it fits under the cover. I'll be making some small changes to it in the next rev.
Pat... I wonder if there's a way to make a removable yet non-suckable (for lack of a better term) cover for the screw "hole / well"?

I'm just thinking of the cleansest, smoothest air flow, and the screw would no doubt disturb said smooth flow....

Could you fab another "plastic" piece that basically wrapped the screw and at the same time filled the majority of that gap? (Hard to explain.... but the idea is to keep the wall of the V-stack smooth (I know this is not a new concept to you)... Just thinking outloud..

Nice work as always
Mr. Clean
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Sun Sep 18, 2016 7:49 pm quote
oopsclunkthud wrote:
I've ordered some metal mesh that I'm thinking of welding into the lid but not sure it's needed. I've glued the foam to the rubber with pliobond (recommendation of Uni) and it looks like it's bonding really well.
Oh...

The Velocity stack I had custom made by "SteelDragon" has a very fine copper mesh on the inside (case end) His name is Mike and he may have some materials or insight, as that's what he does.

http://www.steeldragonperformance.com/products_2.html

image.jpeg

Mr. Clean
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Sun Sep 18, 2016 7:52 pm quote
And then Inodized:

image.jpeg

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Sun Sep 18, 2016 8:20 pm quote
I'm STILL hunting down my Gravy-Bowl version of intake!
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Sun Sep 18, 2016 9:07 pm quote
Vader19 wrote:
I wonder if there's a way to make a removable yet non-suckable (for lack of a better term) cover for the screw "hole / well"?
As in the idle adjustment screw?

At the moment I've eliminated all the screws but the idle adjustment screw, and the spring pressure from that holds the bell in place. This also makes it easier to access the jets, remove the idle adjust screw and the bell lifts off.

While it would be nice to remove the idle adjust screw as well doing so would be hard and would mean finding other ways to hold the bell in place as well as methods to set the idle.

But as long as we are thinking in those lines, A short idle adjust screw with a hex head line a set screw and a nylon nonslip insert on the threads could do the job. Then there would just need to be a hole to fit a 2.5 hex key. Another way would be to modify the slide cover to hold an adjuster that stops the slide. The Dellorto SS1 had an idle stop like this.

Here's a cut away to help show how the bell in held in place a the moment.

Screen Shot 2016-09-18 at 22.05.00 .png

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