Airbox mod's Pics added, Update and the future

[treedragon]

Edit: This got a bit long winded, sorry.

Hi all, just thought I would share two internal airbox mods and the results.

I'm running the standard airbox with flapper, the motor is standard other than the freer flowing Cycle Works exhaust, (similar setup to standard units). Actually the bike is overdue for a good tuneup, and I have no idea what jetting I am running.

Mod #1 For some time now I have had been using a free flowing air filter made by modifying the original. I took it apart and removed all the pleated filter material but left the wire mesh. On the top face of the filter I cut out the stepped in section (leaving the lip for the side mesh. and replaced it with some wire mesh. The whole thing was re-glued back together with a hot melt glue gun, (great things those).

Out of filter foam I made a band to go around the perimeter (where the pleats were) and I hot glued a piece on top, oiled it all. Drilled some holes in the two "walls" on the lid that hold the filter in place so the air had a slightly more direct access to the go department. Works well, things certainly seemed "sharper" afterwards but I wouldn't necessarily say there was any great difference.

Mod #2 It has always seemed to me there should be more "punch" available and although I know the carbs when set right, work well........... but I felt an avenue for experimentation was the inlets. I decided to make the inlet tracts longer for better air velocity.

Never being one to put more effort than necessary into things the canary had to fly around the cage a few times before finding the open door and then I had my aha! moment.  I had some extra airboxes floating around the place and as chance would have it the rubber inlets looked suspiciously like they could be made to fit.....

On the pair fitted to the carbs I cut the trumpet lips off at where they just become parallel, the spare set, untouched, fitted neatly over them doubling the trumpet length pretty much. The extended rear one fits partly inside the filter case, I have it tipped forward slightly, still plenty of room for good airflow.

Results:
Giving it a good blip at standstill, gets a wildly accelerating roar with added bass note from changed induction noise but then again my ears are getting old and I was having a good day. I took a short test ride to make sure all was smooth, it was, had grin factor as well,  ;D  ;D  ;D  needed the weekend ride with the Ducati boys juuuust to check........

Just out of town here we have the Whangamoa Hill, several K's of twisties, good road surface, handling is king here, but horsepower helps. I'm not one to race as such, but I DO LIKE working a bike, my ride performance tends predictable. Standard routine is to get in front and then scream over the hill with a couple of bikes up me date, they are never quite able to get by due to the XZ's excellent cornering speed (thanks to improved handling) and by the time they have caught up on horsepower we are at the next corner....... it's a sort of ride barometer I use.

Today was the same except........... nobody could keep up, at best several corners behind  8)  8)  8)
The bike has way better punch out of the corners and improved acceleration. I LIKE IT!

So I recommend trying this modification, it's easy to do, cheap, and may even work well with the standard filter element. The results are nothing wildly spectacular but it does lift the performance several notches. It also seems the fuel economy may have got a little better when pushing things, but the jury is out on this.

As always YMMV have backup bits on hand.

[The Prophet of Doom]

You just KNOW that the guys will be demading pics.

When I bought my 550, it had filter socks (no airbox) and very different main and air jets (I forget what now).  Sounded great and ran like a cut cat at WOT, but crap around town so I put it back to stock.  Still ran like crap off idle and now I know it was YICS issues.  I am very tempted to have another go, but not without an exhaust analyser I think.

[treedragon]

and that reminds me I haven't had a YICS for a very long time. No performance difference on the open road but the bike idles way better without it.

[Rick G]

My first Vision parts bike had the sir box removed and a set  of pod filters on it . It was way beyond running . Many "home tuners " junked the air box and tried all kinds of stuff to get it to run with out it .
By the way your problem is not because of the lack of a YIKS box . I tossed mine, around 2 years ago, when it started leaking,again. The YIKS box was designed for four cylinder engines and does very little on a twin. (ask Jason)

[YellowJacket!]

A picture is worth 1024 words.  8)

David

[fret not]

"YICS designed for 4 cylinder motors" . . . . Thanks for that, Rick. 

Does any manufacturer currently use that  "technology"?  I am not aware of any.

[treedragon]

Okay then some pics I saw were needed.
I've done quite a few hundred k since doing it and I am not going back to standard

[jasonm.]

"YICS designed for 4 cylinder motors" . . . . Thanks for that, Rick. 

Does any manufacturer currently use that  "technology"?  I am not aware of any.

It was done on many Yamahas in the early 80's. Some 4 cylinders as well. Other than that...I know of none.

[Rikugun]

treedragon - There seems to be something missing from that airbox - oil! Did you clean it up for the photo shoot or does my engine just have too much blow-by?

It seems that oil is blown in from the rear cylinder via the crankcase breather then runs back into the engine via the smaller hose at the front of the airbox down into the front valve cover. Is this normal for a V?

[QBS]

Yes.

[treedragon]

No clean up, there is a light film of oil there, and that's it after about 800k. I did clean it a little bit when I put the extensions on, but there wasn't much there anyway from a period of several 10's of thousand k's, and I am pretty liberal with oil on the filter foam.

I always use Valvoline  Racing Formula 50, it seems to hold it's body better than most oils, so that might(?) be something to do with it.

[treedragon]

A bit more info.

Okay a few more k's on the clock now, yesterdays run with the Ducati boys was particularly interesting and confirmed absolutely a few things. The run was corner rich to say the least and the first section saw me working the bike to the max, lot's of revs, lot's of throttle twisting = heavy fuel consumption.

Got to first fuel stop and the pump stopped pumping way too soon.........  It must have made an impact as I heard "C'mon put the pump back and stop looking like a stunned mullet......."  2.5k's per litre better fuel economy than the absolute best I could hope for under those conditions. It was the same all day. I keep accurate records.

So in summary the trumpet modifications have given:

More torque out of the corners
Better high rev performance (as judged by acceleration against known bikes AND gut feel)
Better fuel economy

This bike likes me............... must remember to give it a bowl of warm milk.

This brings to mind the next steps, more airbox modifications.
The current setup of standard filter (modified) does interrupt airflow and it's speed, it doesn't feel ideal yet, (gut feeling again and any excuse to fiddle ). I am going to ditch the air filter and remove the flapper and remake the rear of the airbox top as big as I can within the confines of the tank, basically square it up.

and just in case you are worried by the no flapper comment...........  ::)  ;D
I will mount it in the front of the airbox lid, it is a tight fit but gives access to to the coolest air possible.

For filtration:   inside the airbox base I will cut down the division between the front section and the filtered section and use it as a support for a flat filter element of some description, yet to be made, I can get better filtration than the current setup

[Night Vision]

A bit more info.

This bike likes me............... must remember to give it a bowl of warm milk.

thats a huge part in a Vision relationship....I find myself giving mine a pat on the tank and a "thanks for the ride" quite often.


.....afterwards, please post some helmet cam vids of the ducks behind you...  ;D
it would also be helpful if you post a summary of your final settings

[vadasz1]

I think a detailed sticky will be in order.  As I think many Visionaries will do these mods.

[treedragon]

What I would strongly suggest is that others find some way of temporarily extending their trumpets, basically doubled, and testing for themselves, you don't need the filter just to try it. If it works for you then do the filter mod. My jet setup is 130 mains  180 air pilot (i think that's it name it's the big one inside the carb bowl) and 125 for the ones down the carb throat, all standard stuff.  Since first posting I have done quite a few more k's and the improved fuel economy is still there even at more cruisy speeds

Current developments here are.......

I now have a Weber carb off a Ducati Paso that is catching my attention somewhat......
and as the aim is to get the horsepower out of the motor that Cosworth originally designed into it (I have the cams) I feel the stock carbs are not up to the job, excellent when set up right on a stock bike but.......... well new headers are not too far off, I've got to the point of sorting out the stainless pipe for them......

However I have a number of airboxes to play with so will continue with experimentation on set up as it stands as it stands.

[Raj1988]

I DID IT last week and LOVE it.. Running wit stock paper filter and no Flapper :o

Flapper gives me a hell of a bog intermettently between 4.5 and 6 and off idle.... But now its absolutely brilliant

Even better ... as some of you know, I am on My return trip back across the Continent. On the way up and up until i did the mod, I was getting about 160-180 kilometer per tank (before reserve).. Now i get am averaging 198 over an 800 km test today...

NO stumble and feel like a different bike. Even Vibes are down ... WTF !!!

Tree, Thank you....

Can you explain how and why this mod works ? I did some looking up (old fluids dynamics text book) and seems that this mod reduced turbulence and directs air.. couuld not find anything about speeding up airflow...!! Am i missing the point here?

[treedragon]

Okay the first thing I am going to do is try mine again with no flapper, in about 20 min to be precise, just to check again

My theory was that there would be reduced turbulence, as you say, with the longer air tract and less chance of the air stream breaking down ie better flow in what is basically an intermitant flow situation. As mentioned on this forum the carbs are sort of too big  so increasing the velocity seemed to me  a way of improving performance.

Another thing I was going to try was doing the old car trick with inlet trumpets of putting a flat plate around the trumpets just below the lip to decrease turbulence even more. I you can find a smoker around the place get them to blow a stream of smoke over the assorted edges and you will see the turbulence.

Anyway I'm off to de flapper again. will report back soon.

Edit:  I tried an air box top with no flapper unit at all and got the expected result, serious bog downs up to around 5000rpm tapering off until 6000rpm and then the bike took off........... really rather well. However I'm putting the flapper top back on.

There was useful data to be had though as I hadn't tried wringing it's neck in the higher rev range, with an improvement yet again over my alterations with excellent acceleration (for an XZ). I noticed the other day when checking the carbs that my accelerator pump starts firing fuel at the slightest throttle movement, I think I will have to try setting it to delay a little. Under the test I just did (and other observations) I got the distinct impression the stumble in this instance was way too much fuel in the initial opening, and thus a bog down. As posted elsewhere this is a tuneable aspect...... needs playing with before I get the Weber on.

Raj great to get feedback thank you. Just curious what exactly do you mean by no flapper, no flapper box, flapper disconnected with vacuum line blocked off, flapper box in but no flap.........

[Raj1988]

NA 82's came with out a vacuum acctuated flap mechanism... mine is one of these with just the lose flap(which seems a lil weighted ) with no nickles or dimes or anything glued on to it.

[Night Vision]

...... My jet setup is 130 mains  180 air pilot (i think that's it name it's the big one inside the carb bowl) and 125 for the ones down the carb throat, all standard stuff.  .......

ok, 130 mains, on the left sides of the carbs behind the bass hex nuts correct?

180 air pilots on the top of the carbs?

and where is this 125 jet?

I'm confused  ???

[Rikugun]

I took him to mean the 125's are in the air horns and 130 mains.

180 air pilot

Treedragon, was this mis-typed?