double inlet airbox

[wiseanhyzer]

So I bit the bullet a couple of weeks ago and butchered the airbox. I'd been looking forward to trying the double inlet modification. The results from members here, and on the other forum were all positive. Recipe calls for the K&N or Uni filter to be opened on both ends. Opening the airbox on each side of the filter to the maximum size and pulling the restrictor plate out. Dremel tool and some small hand files made easy work of it. Jetting recommendations are 135 mains. I also switched out the carb needle for Thruxton ones, courtesy of Tribear. Mixture screws are at 2 turns out.

Here is what the airbox looks like after the cutting, and put back together:

And with the filter in place:

On the right side of the airbox, it looks like this:

I thought that looked vulnerable to dirt slinging up from the chain towards the filter opening. So I cut a piece of angle aluminum to exopy onto the outside of the airbox. Hopefully it will keep some grit from being sucked into the filter and hanging out in the bottom. Not that any of that would pass through.

Here is what the aluminum piece looked like after I cut, bent, and painted it black to blend in"

Here is what it looks like in place:

I used an epoxy called Plastic Welder picked up at the hardware store. It seemed to work really well to bond the alum and plastic airbox together.

I am VERY pleased with the results. The bike runs as smooth or smoother than before and is MUCH stronger. Starting, idle, and warm up are no different than before. So far I haven't seen any change in MPG. I was consistently getting 45 - 47 mpg commuting. When I get used to the change and quit twisting the throttle for thrills, it'll probably get better. The difference in the intake noise gives the bike a deeper tone. I'd never go back, no way. There is NOTHING about this modification that I regret. The biggest difference that I notice is that it has given each gear so much "more". I shift less in traffic than before. I stay in 3rd at speeds I used to bounce between 3rd and 4th. Same for 4th and bouncing between 4th / 5th. I don't find myself trying to shift into 6th anymore. I don't really care about the top speed. But the bike performs much stronger all the way through.

This is a great way to squeeze more performance out of the twin. Cheap too. It's got my stamp of approval. Fire away with your insults or questions. :cheers:

 

[JimVonBaden]

Nice, I did a similar, though not so nice, job on mine!

Jim

 

[GuyM]

I particularly like that little aluminum dirt guard... Nicely done.

 

[sportyone]

no insult, but I have to question why really, you would disregard the designers plan for effective and dust illiminating airbox design, now IMHO you have opened the filter to even more additional dirt and road dust etc. a total box chop is fine or even to de snorkle and fit a venturi. but what you have done I am not sure ? :huh:
open your car bonnet and check out the amount of sand and grit that get blown in and sit in the wells and crevices of the engine bay. you will really have to keep an eye on dirt especially on the chain side now, seeing you might be running with no chain guard too. :eeek:

 

[sweatmachine]

hey sportyone, lots of people have been running with chopped (or no) airboxes, and no chainguards, for a long time with no ill effects. Maybe if you'd speak from experience, or keep your mouth shut, rather than nay-saying, you'd learn something.

:attn:

Also, the quote in your signature line is wrong. It's supposed to be "You live more in five minutes on a bike like that, going flat out, than some people live in a lifetime."

 

[sandgrounder]

.....why really, you would disregard the designers plan for effective and dust illiminating airbox design,

I think you'd be a little more accurate if you wrote "designers plan for effective noise and harmful emissions illiminating airbox design"

The airbox in this instance is allowing the filter to be opened up to increased air supply.
Thereby causing less restriction and increased airflow to the carbs.
The filter is still there to protect against ingress of dust, sand and grit so no harm is done.

And with a bit of rejetting, the performance gains will be very noticable.

FAR more than de-snorkling and venturi fitting would ever do!!

 

[JimVonBaden]

Not to mention that, even though you opened the other side, the filter is still filtering 100% of the air. So you wont be getting any more dirt in it now than before.

Jim :brow

 

[wiseanhyzer]

no insult, but I have to question why really, you would disregard the designers plan for effective and dust illiminating airbox design, now IMHO you have opened the filter to even more additional dirt and road dust etc. a total box chop is fine or even to de snorkle and fit a venturi. but what you have done I am not sure ? :huh:
open your car bonnet and check out the amount of sand and grit that get blown in and sit in the wells and crevices of the engine bay. you will really have to keep an eye on dirt especially on the chain side now, seeing you might be running with no chain guard too. :eeek:

No insult taken. If I decide that I f'd up by doing this, I can pick up a complete airbox on ebay relatively cheap and go back. But I doubt I will.

I'll keep an eye on the dirt and dust for sure. I've got a K&N filter, so I can clean it as often as I need to. If I had chopped the airbox, or removed it completely, pod filters would be every bit as susceptible to dust and crap. I'm confident that the filter will do it's job and clean the air before entering the carbs.

 

[sportyone]

hey sportyone, lots of people have been running with chopped (or no) airboxes, and no chainguards, for a long time with no ill effects. Maybe if you'd speak from experience, or keep your mouth shut, rather than nay-saying, you'd learn something.

:attn:

Also, the quote in your signature line is wrong. It's supposed to be "You live more in five minutes on a bike like that, going flat out, than some people live in a lifetime."

WTF, man your touchy, why do you think your the only smart guy here ? your the one that needs to pay attention,
that's real smart coming from someone who is supposed to know so much about everything ( well you tell us that anyway ) who hadn't checked his own chain adjustment until many had to tell you about your chains lack of adjustment, after posting a foto of your bike, smartarse !

my comment was based on the guys hacking out the side of the air box & filter above the chain ! off course many have removed the airbox completely and perhaps foolishly the guard too, but if you have pod filters on the carbs that's fine.

I have learnt alot from this forum and that is, there are alot of rude fools that think they own the site, & if you don't come from the good ol' USA, no one will notice your post, your bike or your comments, mod ideas etc & just bag you ?.

even when I wrote we in OZ have access to a great tuning guy sometime back, all hell broke loose with loads of rubbishing posts. childish & total stupidity really. I enjoy this site but you do need to weed through the crap if you are to really get the facts right.

Now you even want to correct my signature, so is that another controlling thing for you too ?

if I change it for you will that please you ???

 

[sportyone]

No insult taken. If I decide that I f'd up by doing this, I can pick up a complete airbox on ebay relatively cheap and go back. But I doubt I will.

I'll keep an eye on the dirt and dust for sure. I've got a K&N filter, so I can clean it as often as I need to. If I had chopped the airbox, or removed it completely, pod filters would be every bit as susceptible to dust and crap. I'm confident that the filter will do it's job and clean the air before entering the carbs.

great, I mealy was stating an opinion that's all, some feel I am wrong but that's cool, some people are like that on here.

I too have done some mods however I have chosen to keep the bike as close to standard classic looking as possible. and by having it tuned well it performs fantastic.
I ride each day for pleasure and I am not trying to race the bike so I suppose it's different stokes for different folks, after all it's your bike and you did ask for comments

 

[sandgrounder]

........after all it's your bike and you did ask for comments

It could be that your "comments" were more construed as critisism of wiseanhyzer's work on his bike and the direction he'd taken with the airbox.

Certainly looked like it from here!

 

[sportyone]

Not to mention that, even though you opened the other side, the filter is still filtering 100% of the air. So you wont be getting any more dirt in it now than before.

Jim :brow

well mate, it is said, I beleive somewhere on here that K&N by the very nature of their greater air flow, could draw in more dust, dirt & grit.
opening up air box to expose the filter to even more rubbish could be a problem. IMO
If you bothered to read my comments you would have seen I just said, "you will really have to keep an eye on dirt especially on the chain side now, seeing you might be running with no chain guard too."

meaning, you'll have the check and clean the filter more often :c

 

[sportyone]

It could be that your "comments" were more construed as critisism of wiseanhyzer's work on his bike and the direction he'd taken with the airbox.

Certainly looked like it from here!

WOW, is this how world wars start ?

everyone sees what was said differently,
thank goodness wiseanhyzer who posted and request comments and insults,
has said that he took my comments without insult !!

so WTF are you all on about

 

[sweatmachine]

WTF, man your touchy, why do you think your the only smart guy here ? your the one that needs to pay attention,
that's real smart coming from someone who is supposed to know so much about everything ( well you tell us that anyway ) who hadn't checked his own chain adjustment until many had to tell you about your chains lack of adjustment, after posting a foto of your bike, smartarse !

my comment was based on the guys hacking out the side of the air box & filter above the chain ! off course many have removed the airbox completely and perhaps foolishly the guard too, but if you have pod filters on the carbs that's fine.

I have learnt alot from this forum and that is, there are alot of rude fools that think they own the site, & if you don't come from the good ol' USA, no one will notice your post, your bike or your comments, mod ideas etc & just bag you ?.

even when I wrote we in OZ have access to a great tuning guy sometime back, all hell broke loose with loads of rubbishing posts. childish & total stupidity really. I enjoy this site but you do need to weed through the crap if you are to really get the facts right.

Now you even want to correct my signature, so is that another controlling thing for you too ?

if I change it for you will that please you ???

hey dipwad, first of all I adjusted my chain before posting the pictures. That same day I had removed the rear wheel to clean the chain, reinstalled it, took it for a ride, took the pics, and I noticed the chain was loose when I got home so I tightened it before posting the pics.

Of course, I don't care what you think about me, my bike, or anything else.

Your signature line has a quote in it. You mis-quoted. That's dumb.

You're the touchy one!

 

[tribear]

Nice work Wise!
The performance gain is incredible isn't it?! Glad you are happy with the thrux needles. Upon close inspection of air inlets between the airbox and carbs I have found no dust or debris after riding in some pretty dusty dirty conditions. The K&N is doing it's job quite well on my rig.

 

[wiseanhyzer]

Nice work Wise!
The performance gain is incredible isn't it?! Glad you are happy with the thrux needles. Upon close inspection of air inlets between the airbox and carbs I have found no dust or debris after riding in some pretty dusty dirty conditions. The K&N is doing it's job quite well on my rig.

Excellent. Thanks again for passing on the Thrux needles!

 

[koifarm]

What I like about Wise's post was the very neat and workmanlike job he did. Quite meticulous and well thought out and executed, a wonderful example of the proper and neat way to do the job and with the air filter still in place doing it's job.
IMHO when you run, x amount of air enters through the stock setup. You allow more air on board with a mod, you need to look at carb adjustments to compensate, Wise did, the job looks first rate and he took care to set the carbs the right way.
Job well and rightly done. He was nice enough to take the effort to share it with us.
I, for one, would like to see any further posts he makes and hope he still does after the flak settles...
koi