Different take on air box modification

Hi all. Well I thought I had an original idea but here's what I did yesterday. The thing I haven't like about other mod's out their is that IMHO rain water can get sucked in because there compromising the protection. My back round is industrial heating/cooling and we do all sorts of air, water and oil filtration. Have been reading about the air box and I have to ride 1 mile on dirt roads between the house and the highway so I thought I'd check my filter. Held the filter up to the sun and saw that most of the dirt was on the back end of the filter with the near side being mostly clean. Naturally the culprit is the intake tube which blocks about 1/3 of the filter, and the air will take the path of least resistance. Also with the throttle tubes stacked on top of one another it seems the far side 2 will gulp most of the air during throttle response over the 2 near side tubes. Here's some pic links. Sorry haven't figured out how to get them into the post yet:

https://i1066.photobu...ti/P1010138.jpg

https://i1066.photobu...ti/P1010143.jpg

https://i1066.photobu...ti/P1010140.jpg

used a 7/8 hole saw and then just the auger bit for the smaller holes. Here's what it looks like installed:

https://i1066.photobu...ti/P1010147.jpg

https://i1066.photobu...ti/P1010146.jpg

I also drilled some smaller holes in the outer cover to allow more air in:

https://i1066.photobu...ti/P1010149.jpg

BTW- while I was in here I used the dremel to notch out the plastic and route that pesky wiring outta the way:

https://i1066.photobu...ti/P1010144.jpg

https://i1066.photobu...ti/P1010145.jpg

After reassembling and starting I notice my idle is now up from 1200rpm to 1600 rpm. Went for a short ride (wind gust up to 50mph) but notice throttle response is better. Use to have a small lag. It's gone. Weather is gonna be lousy and chance to do 100 mile trip to work and back will B Wednesday. I'll post again if I notice any other changes. It took about 15 minutes to do this and re-assemble. Be safe all.

Yer Photobucket album must be set to private, 'cause the linkies die.

And if you use the 4th line of code from the menu that drops down as you hover over a photobucket thumbnail, it'll post the picture and not just a link to the picture. Makes the post much more interesting.

But it can't be a private album.

Thanks for the heads up wfooshee. I've check photobucket and everything appears to be set to public. When I tried the links earlier they work. Can't check again till tonite with home computer. Thanks for the picture posting info also :-D I'll work on the links tonite. Wait a minute. This post was a editied copy of my post in another disussion. Wonder if that has anything to do with it? Will try editing and actually pasting from photobucket. Stand by.

Yep. That was the problem. Couldn't edit the original post but here's the pictures to go along with it. They should be in the correct order pertaining to the post wording. If any body has any ?'s email me.

Nice job, but that's a lot of work on a piece that should just be removed anyway. Removing it will in no way allow water into your air box. There were some concerns about CDog's hole on the right side, but in all the miles since the mod, I haven't seen any signs of water intrusion.

That dremmeled notch for the wiring is a fantastic idea. May do that at my next service since it'll be time to check/change the filter anyway.

After a couple hundred thousand miles on FJRs and when replacing the air filter and always seeing this:



I finally did this:





While that improved things, there were still 'clean' areas on the old air filter when replacing it, so I ended up sawing the whole interior tube off. Thought I took photos of that but can't find them.

The purpose of that thing you cut off there is probably to place the effective air inlet of the air box equidistant from the four intake tubes so that they can all suck in equal amounts of air. Cutting it off may cause some imbalance. Cutting another inlet opening into the air box on the opposite side of the existing inlet would balance it out again, and potentially allow more airflow.

This is known as "Cdog's air box mod": https://www.fjrforum.com/forum//index.php?showtopic=105719

UselessPickles said:

The purpose of that thing you cut off there is probably to place the effective air inlet of the air box equidistant from the four intake tubes so that they can all suck in equal amounts of air. Cutting it off may cause some imbalance. Cutting another inlet opening into the air box on the opposite side of the existing inlet would balance it out again, and potentially allow more airflow.

This is known as "Cdog's air box mod": https://www.fjrforum.com/forum//index.php?showtopic=105719

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Interesting theory, but I have my doubts. The end of the tube is not equidistant to the four intake tubes. At least not to my eye. The left two are further away than the right two. And the uneven filtration of the air filter confirms where the air is going - to the right side.

A trusted life-long Yamaha tech is under the opinion it is there for noise reduction - 'intake honk'.

In the end, who knows? I am sure the Yamaha engineers put it there for some reason. I am hesitant to make changes to modern engine designs as I am not one to presume to know more than the engineers who designed the motorcycle.

But, after 15 or so air filter changes and always seeing the uneven dirt accumulation, I just couldn't get off the, 'that just ain't right' thinking and decided to give some modding a try. One thing I definitely DID accomplish was even dirt accumulation on the air filter.

SkooterG said:

A trusted life-long Yamaha tech is under the opinion it is there for noise reduction - 'intake honk'.

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So my bike should sound like one of these if I cut that off?

The chunk you klowns cut off keeps the intake from inhaling yer pecker..

Dipshits. :dribble:

Yeah I was toying with the idea of just cutting the whole tube off, but since this was the 1st mod I came up with(kudos to the other idea's out there) which gave me the inspiration I thought I'd play it safe and start this way. I'll be able to get a 100 mile ride in Wensday so I'll post any thing else I notice.

SkooterG said:

In the end, who knows? I am sure the Yamaha engineers put it there for some reason. I am hesitant to make changes to modern engine designs as I am not one to presume to know more than the engineers who designed the motorcycle.

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+1

SkooterG said:

But, after 15 or so air filter changes and always seeing the uneven dirt accumulation, I just couldn't get off the, 'that just ain't right' thinking and decided to give some modding a try. One thing I definitely DID accomplish was even dirt accumulation on the air filter.

Click to expand...

Maybe taking it out periodically during the filter's service life and turning it around would yield the same results?

exskibum

Posted 03 April 2012 - 08:15 AM

View PostSkooterG, on 02 April 2012 - 07:43 PM, said:

In the end, who knows? I am sure the Yamaha engineers put it there for some reason. I am hesitant to make changes to modern engine designs as I am not one to presume to know more than the engineers who designed the motorcycle.

+1

View PostSkooterG, on 02 April 2012 - 07:43 PM, said:

But, after 15 or so air filter changes and always seeing the uneven dirt accumulation, I just couldn't get off the, 'that just ain't right' thinking and decided to give some modding a try. One thing I definitely DID accomplish was even dirt accumulation on the air filter.

Maybe taking it out periodically during the filter's service life and turning it around would yield the same results?

The even dirt accumulation is a good sign. What Skooter, others, and I noticed was that before air box modification dirt accumulated on the back end of the filter, while the front(blocked by inlet tube) remained relatively clean. The evening of accumulation shows that the mod is exposing more of the filter to incoming air, which should allow the throttle intakes easier access to the air.

While it's not scientific by any means I've increase my average mpg from 43-44 to 46 @ hway speeds of 75-85 Sometimes alittle faster

I've been thinking of simply cutting off the snorkel as well. Many other bikes have them in places where it absolutely has nothing to do with equalizing airflow to the intake tubes, so I kind of doubt that theory as well.

However, I think if the 'dirty' side of the filter actually got dirty enough to impede airflow, the air would simply start to transition over to the cleaner part of the air filter?

I still might cut the SOB off, maybe it will make wheelies easier.

Screw that airbox BS....that's what THESE are for --

RadioHowie said:

Screw that airbox BS....that's what THESE are for --

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FECK, YES! And while you are at it go ahead and add four Amal Concentric Mark One Carburetors, if they were good enough for the Vincent Black Shadow and the BSA Gold Star they sure as Hell are good enough for the FJR!

RadioHowie said:

Screw that airbox BS....that's what THESE are for --

Click to expand...

So do it!

SkooterG said:

RadioHowie said:

Screw that airbox BS....that's what THESE are for --

Click to expand...

So do it!

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What makes you think I haven't?????