Foam in air box

[mjpchief]

What purpose does the foam before the air filter serve in the airbox besides muffle air intake? Also are the metal covers needed on the carb holders? This is on an XS650B. Thanks in advance.

 

[Downeaster]

Assuming the carbs are stock, they are jetted for the air flow provided by the stock setup.

While you CAN remove the foam, you'll need to check the jetting if you do.

Not sure what you mean by metal covers on the carb holders.

 

[weekendrider]

You have more/extra foam besides what shown as part #8?
The shroud (part #3) adds to the rigidity and keeps the clamp from cutting part #2.

 

[mjpchief]

My bike is a '75 XS650B. The airboxes are different from the ones shown in your post. They have a piece of foam in the intake part of the airbox before the filter. These pieces of foam are rotten and probably need to be replaced. I have new airfilters going in but was wondering if the pieces of foam before the filters were needed. I will put the metal sleeves (#3) on my new carb holders. I had installed the holders before I realized the sleeves were removable from the old holders. Thanks guys.

 

[Downeaster]

Do the elements themselves have a foam "sock" over them? If so, I'd be comfortable with just trashing the nasty foam in the box.

 

[mjpchief]

Yes the main filters have foam on them. I will run it without the foam blocks in the box for a while and see how it does. I have already installed the sleeves on the carb holders. 30 minute job. Makes me feel better whether they are needed or not.

 

[mjpchief]

These foam blocks I am talking about were not used as filters because they had many 3/8" holes through them. I am pretty sure they were just there to help cut down on intake noise. Kinda like taking the air filter off of your carb on your car when you were a kid to make it make more noise when punching it for the crowd.

 

[weekendrider]

Intake silencers is what the schematic calls them. No Longer Available.
I wonder if they could be recreated from a block of foam?

 

[mjpchief]

If needed I'll pick up some foam from local hardware store and use it.

 

[mjpchief]

Took it out for a spin today and it ran pretty good. Needs a little fine tuning in idle mode but I've got a couple of days coming up to do that. It's supposed to snow here tomorrow.

 

[jayel]

they were used to reduce intake noise, easiest replacement is to use a couple of nylon pot scrubbers per side

 

[mjpchief]

Didn't seem to be too noisy. But I don't here as good as I did when I bought it either. Probably won't worry about it.