OEM air box vs. K&M tapered filters

[mfarrington]

I recently purchased my 79 XS1100 SF and it had K&N cones. I lost one on the road, and am wondering if I'm better off with a OEM air box or the after market. Thanks for your thoughts.

Mike Farrington

[81xsproject]

I fixed ya from K&M to K&N. Also, you might just want to do some 'searching' in the forum posts. There have been about 571 different threads/debates on this topic.

The long and the short of it are that the OEM box CAN yield better low end performance due to either the slight flow resistance or longer intake tract. It also leaves no doubt as to how the carburetors should be jetted.

Properly jetted carbs with pods that DO NOT cover the air jets at the mouth of the carbs CAN increase breathing and possibly yield a little more top end.

However, as to date, I don't think that there is any rock solid Dyno-run evidence to support either claim.

Just do the research on the forum and decide who YOU want to believe.

[mro]

I personly like the stock air box,
but if your bike is running good with the pods would stay with em.
They are kinda cool looking. Have stock box on my XSes except the hot rod which has K&N and they look OK. Use a good quality SS clamp and should not fall off agin.


mro

[thewiz]

I have stock air boxes on all of my XS's .... even the ones with headers and aftermarket carbs .... and while a pain to R&R for carb work, probably still the best way to go .... how much more performance than a well tuned stock XS does one really need anyway, I wonder?

[Crazcnuk]

Also, the pods are somewhat noisier as you can hear the intake noise much better.

More noticable behind a fairing, I would imagine.

[81xsproject]

Oh yeah! I LOVE that sound!

[mason79]

if it runs well now, just wait till you get a stock box.

pros: stock

quieter
predictable tunability even with aftermarket exhaust
more chrome
support of the carbs?
no greasy fingers when you touch the pods
someplace to vent and recirculate the crankcase and carbs other than just to the apnosphere (spell?)
wash your bike without worrying about blasting another place on the bike that water will harm like the gauge cluster area
would not fall off due to neglect or inattention

cons:stock

hard as heck to learn the technique to remove and replace
after you learn you still cringe at the tought
some don't like the stock look
less power on top? this could be a myth as the factory tuned the whole system to perform in a broad range
heavier, this alone can ruin your 1/4 times from flat 16 secs to 17 seconds


i run stock i went the other way and it ran well but when i went back to stock it rips a new hole.

[fredintoon]

Hi mf,
If the bike was properly set up to run with K&Ns, the simplest thing is to go buy another one. You may want to look at making a support to hold the carbs steady, the stock airbox did that but any kinda pod won't and perhaps that's why your K&N fell off.
The only way you'll notice a performance difference between the stock airbox and the K&Ns (assuming the bike was properly set up for each system) is when you are way over the speed limit.
For me, no problem with the stock airbox' performance but I hate the knucklebusting nightmare involved in getting the pig off to work on the carbs. Which I had to do A LOT this spring because the crud of ages was making it from the rusted tank, through ALL my gas filters and bunging up my carbs for a pastime. Now I run 4 individual oil on foam air filters that can be removed in 5 minutes. Of course, the carbs have never needed cleaning since. And that's good insurance.

[81xsproject]

Making a carb brace is very easy. I can't remember if I posted pics and stuff of mine but it simply goes from the forward regulator bolt (replaced with a longer bolt) to the one of the screws on the rear carb mounting rack. Took me all of an hour to fab it up.

[81xsproject]

I knew I had a pic somewhere. This pic must be right after I ultrasonic cleaned the carbs, they still look REALLY CLEAN.

[Gyrogearloose]

I've had trouble with the stock airbox on my 80SG. The PO had squeezed the filter down so much that it buckled the sides of it! Anyway, had a little trouble getting to the point where I was assurred the new filter was seated right and properly in place. Also it seems to me the wing nuts need retightening every once in a while (part of the periodic check) before riding. Other'n that I like the chrome sides of the airbox, and it sounds gooood with all four carbs sucking when I open her up. Yah!

[snowdog51]

pods

i love that sound with pods.
as ever bill

[pggg]

Why the stock airbox is so good, 4 big velocity stacks inside, good for low down drive/grunt out of corners etc..

[81xsproject]

Right you are, pggg. Which is why I recommend ditching the airbox and just doing one of THESE mods

[thewiz]

Very cool, 81 ....

Doesn't look like there is much dead weight to the donkey dicks ... so ...... no need for a carb support brace, right?

Originally posted by 81xsproject
Right you are, pggg. Which is why I recommend ditching the airbox and just doing one of THESE mods