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Lol. Please check appropriate box.




 

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hold onto your undies cuz I'm about make a very big deal about 3 little pieces of foam that may be the cheapest items on your bike aside from the air in yer tires and remove all doubt:p.
Well, I'll be damned! THAT'S what that ratty old foam is for!

Lizard, you are gem we are lucky to have on the Forum....("he said on the way to the store to get some foam and vacuum T's"):cool:
 

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It's FRIday! On Fridays here they untie my sleeves and give me crayons!

In commemoration of Crayon Day (and because I've nothing better to do, like RIDE):

Our bikes (most bikes, nowadays) have at least a rudimentary form of ram air, or at least a means of collecting and directing a fair amount of air toward the airbox entrance. Here's my third grader's effort to illustrate ours. Ok, more like a first grader. So what?:



Air gets wedged between the seat, the airbox and the side covers, then the little "dam" thingy protruding from the underside of your seat, combined with the two little filler pieces of foam glued to the sides of it forces the dammed air into the snorkel. The snorkel is located on the right side of the bike, so the little block of foam on the right is slightly more crucial to feeding the snorkel, but combined they seal the end of the "tunnel", thus turning it into a "box". Your side covers, seat and airbox all play a role in creating this "box", so even something as simple as running without your side covers could potentially affect your jetting. The box is far from airtight, but in terms of overall effect it's airtight enough for gummint work when it comes to funneling air.

Now here's a simple air siphon. In this case a sandblaster, but paint sprayers, bug sprayers and some other stuff work the same way.

Pressurized air is fed through a tube, creating a partial vacuum at the junction, which pulls the sand out of the hopper, sends it down the airstream and you get waycool, shiny parts because the "box" now has an optional exit, making it a constant velocity "tunnel". Muey bueno for sandblasting or executing cucarachas, no so bueno for an airbox:



Now here's your airbox without those stupid little pieces of foam. It's not unlike our sandblaster now, is it? No foam means there's a hole in the end of your "box" which turns it back into a "tunnel". High speed air now travels OVER the airbox entrance looking for that big hole in the back of the box instead of your snorkel (path of least resistance) and starving your airbox. Much like the air passing over the pickup tube in our sandblaster, but in this case by a certain speed rather than pulling sand out of a hopper it is actually starts trying to suck the AIR out of your airbox, and the faster you goes, the richer you gets. At lower vehicle speeds or at lower RPM the effect is far less dramatic, but in any case it reduces the amount of available air to your airbox and in turn, your carb.



And that is how two identical bikes can get such different results with the same jetting. It's also how something as simple as a gust of wind up the back of yer skirt can bring your bike to a halt,and if you look at where the little pieces of foam are located you can see how they help keep water and stuff from entering from the rear of your "box" and in turn, your airbox..

It also explains why I was payed for all those years for my technical and problem-solving abilities rather my technical illustration abilities:p.
 

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can you post these lessons on the KHAN academy for bike dummies?

the guy's even a master with a white board! thank you!
 

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Veeelllly interestink! I knew the foam prevented water, etc. from getting to the snorkel, but hadn't thought about how it's absence affected jetting. Your sandblaster analogy makes it all clear. Yes, you are definitely a multi-talented man, Lizrdbrth, and an asset to this forum. Thanks for taking the time to enlighten us.

Another reason to be thankful for Fridays!:D
 

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Aight. So in summation regardless of whether or not you have a stock airbox and snorkel, have pulled your snorkel, ventilated your airbox or whatever the case may be I hope that we'll all concede that we'll get ZERO benefit and even considerable detriment without the stoopit foam.

So the next time you hear someone say they have the hot ticket on jetting and airbox mods take it with a grain of salt and concentrate on your own bike.

Maybe they only lacked 10 cents worth of foam to begin with.
 

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v interesting thread this! jut out of interest what year is your bike? mines a 2000 tw125 and my airbox is at the side of the bike not under the seat, well it is but the filter isnt
 

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Lizrdbrth! Yer a stud! I looked at my foam pieces and, even though they must be 20 years old, they are good. This might explain why I have never had carb mixture issues. The air is flowing properly.
 

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v interesting thread this! jut out of interest what year is your bike? mines a 2000 tw125 and my airbox is at the side of the bike not under the seat, well it is but the filter isnt
The airbox intake snorkel should be under the seat, just behind the battery. The filter is on the side but the snorkel is the point from which the airbox draws its air.




 

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The airbox intake snorkel should be under the seat, just behind the battery. The filter is on the side but the snorkel is the point from which the airbox draws its air.
True yes your right
 

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Liz,

if you weren't so smart, I might learn to dislike you. :)

As many times as I have had the seat off messing with the carb, battery and electrical, I never paid any attention to those foam pieces attached to the underside of the seat.

As usual, you are correct, sir.

On my 2005, the foam is still serviceable...still springy and making a seal.



Now I will keep an eye on those foam pieces until you present your improved version.

Thanks for the insight.

jb
 

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Mostly it's the durability of it. But I'm having a heck of a time improving on it. I finally figured out why the factory only glues it to the bottom of the seat pan itself rather than to the sides of the little fender baffle thingy.

I tried additionally gluing it to the sides of the baffle thingy but pulls at the glue when the foam is compressed. Only lasted a week. Guess that's why they let the two foam pieces "float" and tie them together with that little ribbon of foam tape.




 

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Well I'll be damned..never had seat off yet..gonna have to Check that on my 87..sure it's toast! I'm gonna be mudding the hell out of it too...you the man lizrd
 
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I just read this old thread (searching for a tee system to the fuel vent lines) and all I can say is:
"Wow. Lizrdbrth is STILL teaching me things."
Thanks, man, wherever you are.
 

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Lizrdbrth's tubing ,valve amd"tee" can be 1/4" drip irrigation parts if auto store doesn' have on hand. Beg ,buy from Calgary landscaper or irrigation supply like EWING.
My carb vent line terminated in elaborate chrome vanadium "v" shaped fitting that was hopelessly clogged with debris. Could not open up with piano wire, ultrasonics, compressed air nor carb cleaner so I threw it away and replaced with spare mini-fuel filter to act as vent line filter.
Now if I can only find some water to cross in this draught ravaged land I'll let you know if she works.
 
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