The stock Air Box Funnel reduction surgery.....By WW

Ok all,

My conversations with 03HiYoSilver prompted this thread,

THE DISCLAIMER FIRST (from our conversations about HP farkles):

I can't say for sure if the chopped funnel is letting in more air BUT... I was unimpressed with how the interior funnel obstructed half of the the first two cylinder intake tubes. I noticed when I changed my air filter that only the back half(in front of #3 and #4) of it was dirty(only past the funnel). If nothing else, I will be getting longer life out of my air filters(the whole thing should get dirty now). In theory, the air input should be balanced better among all four throttle body tubes. I know, I know, I didn't unleash some hidden beast with the air box mod BUT.. I am adding more fuel than Yamaha could(with the upped CO values..Barbarian mod) because they have to balance performance with emission standards... The stock air box is designed for performance BUT also noise and emission considerations. If I was gonna add a lot of fuel(and didn't care about MPG), I would remove the air box and put 4 independent pod filters. And/Or...... I have considered making a second, equal and exact opposite hole in the right side of the air box. This would be a cheap alternative to the pods, and would add more air. You have to remember that you have to let the extra fuel and air out faster(open up the exhaust) to make all this work correctly. I am not trying to max out HP, just maybe tweak a few more (cheap) ponies to be had by letting in a bit more air and fuel to complement my Exhaust( though I have considered punching out the cat BUT that might be a future farkle).

HERE IS THE MOD:

I bought a new stock Air box cover(has funnel attached to back) from Ronayers.com for less than $15. I trimmed the new one with a dremel and kept the other in case I ever want to put it back stock. The Yamaha part number for my 07 was #5jw-14412-00. I suspect that the the air box is the same on all years But I am not totally sure.

Here is a couple pics of the modified stock door/funnel: Notice that I left enough funnel to still hold the filter in place and I still retained the stock air flow scoop(not pictured) that covers the air box door. So it still retains the stock "suction" created by the 45 degree air flow scoop(not pictured).





Hope this helps anyone considering this simple mod,

WW

I think it would be possible to accomplish the same thing by drilling holes in the scoop. The reason I suggest this is that it would be better holding the filter in place. It might be overkill though I think I'll give it a try.

The very first hot rodding trick I learned was to get more air into the motor!

Thanks for the post.

I'm trying to think of air flow principles as to why they would have put that extention on the filter cover but nothing logical is coming to mind. I can't believe they wasted that extra &.05 worth of plastic for nothing, but neither can I understand what it may do.

Does the engine sound any different with it removed? Louder intake noise? Have you noticed anything different?

I'm sure somebody has experimented with this and can comment on their results or link us to the proper post. I recall reading the length of the intake track affects the pressure inside the box and velocity of the intake air.

FYI: I cut the intake stack on my Royal Star about an inch. I liked the result. So, then I cut it way down. Then the intake noise was too loud. So I put it back to an inch lower than stock. The airbox was directly under the gas tank on that bike.

I have ****** up more good airbox systems then I'd care to admit to. In the final analysis, I have to bow to the engineer that deigns these things. I think two criteria are critical in their design.

1. ample air

2. still air

You go in to an air box with a dremel tool and you almost certainly will compromise the still air thing. Good luck.

Yes,

This has been debated. Chopping the funnel did create a little more intake noise BUT not a lot. I agree that the Yamaha engineers get paid a lot to design these things BUT, they are working within strict noise and emission guidelines(I am not). Anyone knows(that knows how to tune for HP) that the more air and fuel and less exhaust restriction, tuned properly, creates more power. The only debate is whether or not this will allow in more air. At very least, it will even the air distribution to all 4 cylinders. This creates a better tune... I am going to check my TBS today and see if #1 and #2 require an adjustment... I suspect they will if they are getting more air!! I will check back in a couple hours, after I finish a TBS. Last one I did as only 2000 miles ago... And they were spot on after some adjustments.

WW

Wicked Webby said:

Yes,This has been debated. Chopping the funnel did create a little more intake noise BUT not a lot. I agree that the Yamaha engineers get paid a lot to design these things BUT, they are working within strict noise and emission guidelines(I am not). Anyone knows(that knows how to tune for HP) that the more air and fuel and less exhaust restriction, tuned properly, creates more power. The only debate is whether or not this will allow in more air. At very least, it will even the air distribution to all 4 cylinders. This creates a better tune... I am going to check my TBS today and see if #1 and #2 require an adjustment... I suspect they will if they are getting more air!! I will check back in a couple hours, after I finish a TBS. Last one I did as only 2000 miles ago... And they were spot on after some adjustments.

WW

Click to expand...

I look forward to your results.

Wicked Webby said:

Yes,This has been debated. Chopping the funnel did create a little more intake noise BUT not a lot. I agree that the Yamaha engineers get paid a lot to design these things BUT, they are working within strict noise and emission guidelines(I am not). Anyone knows(that knows how to tune for HP) that the more air and fuel and less exhaust restriction, tuned properly, creates more power. The only debate is whether or not this will allow in more air. At very least, it will even the air distribution to all 4 cylinders. This creates a better tune... I am going to check my TBS today and see if #1 and #2 require an adjustment... I suspect they will if they are getting more air!! I will check back in a couple hours, after I finish a TBS. Last one I did as only 2000 miles ago... And they were spot on after some adjustments.

WW

Click to expand...

Don't waste your time... Back when, Joos over at FJROwners.ws experimented at length with the air box and came up nil on all efforts as proved by dyno testing.

Ok, Just finished the TBS... They do get easier the more you do them!!!

It seems that the chopped air box funnel is doing something... As most of you know(AT LEAST THIS IS THE WAY I HAVE DONE MY SYNCS), the #3 cylinder is the base cylinder(don't change it). The #4 cylinder was still right in sync with #3. HOWEVER..........#1 and #2 were way off this time around(way more than they were when I did the last and first Sync.. 2000 miles ago.. with the funnel intact). They dialed in very easily. Thus, I suspect the #1 and #2 cylinders are now getting more air than they were before when the funnel halfway obstructed them both.

Bike seems to be idling very stable(no surges) and no throttle stumble. It should be noted that yesterday I did go +7 on the CO levels(WOW!! What a nice power increase) and I did put the iridium plugs in her about 200 miles ago. BTW, I do have the Remus Hexacones... I might gut the cat at a later date... I will keep you posted.

I know that this air box mod has been debated, some have said it does help and others have said it didn't seem to do anything. I WILL GO ON THE RECORD TO SAY THAT IT DOES ADD AIR... AND THAT EXTRA AIR ALONG WITH THE EXTRA FUEL, I LIKE!! Cheap HP and tweaks are worth it to me.

Thats all I got!

WW

:competitivesmiley:

Nay sayers need not apply here. Just be ready to line up your stock air box to a modified one(that has more fuel tuned with exhaust)and she what you gotta say then!!

I think the real test will be a strong cross wind coming in at 9:00. I chopped an air box once and the thing fell on its *** in a cross wind. Hate it when that happens.

Wicked Webby said:

Nay sayers need not apply here. Just be ready to line up your stock air box to a modified one(that has more fuel tuned with exhaust)and she what you gotta say then!!

Click to expand...

See post #8. While you are wasting your time, kindly blow some coin and provide dyno slips as proof of your new found ponies.

As I've said early, it's been proved a zero sum gain before. Have fun! :bye:

WW,

Thanks for the excellent post(s). We'll see if what TWN said will prove correct or not... in the meantime we're learning something.

03HiYoSilver said:

WW,
Thanks for the excellent post(s). We'll see if what TWN said will prove correct or not... in the meantime we're learning something.

Click to expand...

Just a post-whore doing what he does best...

FJRSTAR said:

Just a post-whore doing what he does best...

Click to expand...

Fine. Don't believe it. Just go over to .ws and do a search of the archives. Of course, you'll prolly wanna stick one of these in there, too. You know, just for that extra fuel savings:



:****:

I beginning to think some of you FJR owners are more anal than BMW owners. :lol:
:tomato2:

Sorry 2wheelNut,

I am not looking to obstruct my air box, but have fun wid dat!! BTW, just because someone else could not find extra power to be had DOESN'T mean it isn't there.

Now NUT,

Lets get to the nucleus of your dissatisfied stand point;

Your over saturation of non-applicable negative post's on this Forum are a tell tale synopsis of your great need of a HUG and KISS!!!

Good God man you have nearly 10,000 posts! :dribble:

HAHAHAHAHAH!!

Thanks for YOUR Input,

WW

XOXOXO

Wicked Webby said:

Thanks for YOUR Input,

Click to expand...

You're most(ly) welcome. Enjoy waisting spending your time is search of airbox horsepower. Just don't forget to post those dyno slips, k?

twowheelnut said:

Wicked Webby said:

Thanks for YOUR Input,

Click to expand...

You're most(ly) welcome. Enjoy waisting spending your time is search of airbox horsepower. Just don't forget to post those dyno slips, k?

Click to expand...

Too late for that comparison...he already chopped two boxes so he doesn't have a baseline to compare to...though he could do a baseline now as 4 chopped boxes should get more power vs two right? eh?

Good luck to WW on his ever driving desire for more power... :clapping:

Thanks Wheat,

Worst case scenario regarding this , no measurable HP gains BUT a longer lasting air filter and a better sync'd motor. At least I know that the first two cylinders are getting more air now.

WW