1977 XS650 Air Filter

[Runnriot]

I have read through a lot of the posts on here and am having a hard time find a clear response on Air Filters:

I currently have installed the MikesXS OEM Air Filter: Part # 15-0653. The foam has chunked off.

Do you recommend completely replacing with the same OEM? Or as I have seen everywhere replace the foam itself over the existing cage and use a UNI foam filter sheet.

If i use the UNI filter sheet do i need to do anything with the carbs or will the air flow be similar? (Im seeing the UNI's have to get soaked with oil too)

Thanks for the help ahead of time.

 

[hovel]

I like the DIY approach with the UNI or other green foam filter element. Also look at what is known as a pre-filter for small engines, might be easier to work with, maybe a couple of layers. Yes, the UNI stuff has to be oiled. I don't know how thick the UNI stuff is but the easiest way to cut or slice bulk foam is with an electric carving knife. Years back I had the bright idea to make a pre-filter out of some of my wife's panty hose. Mistake, mistake, mistake. It absolutely would not flow enough air. Watch your plug color and watch for puffs of black smoke out of the muffler, a sure sign of an over-filtered rich condition.

 

[5twins]

Don't soak it with oil either, a light coating is all that's needed.

 

[Runnriot]

I like the DIY approach with the UNI or other green foam filter element. Also look at what is known as a pre-filter for small engines, might be easier to work with, maybe a couple of layers. Yes, the UNI stuff has to be oiled. I don't know how thick the UNI stuff is but the easiest way to cut or slice bulk foam is with an electric carving knife. Years back I had the bright idea to make a pre-filter out of some of my wife's panty hose. Mistake, mistake, mistake. It absolutely would not flow enough air. Watch your plug color and watch for puffs of black smoke out of the muffler, a sure sign of an over-filtered rich condition.

With the UNI foam filter does the carb need to be adjusted at all for the air flow or are those fairly similar to the originals? Or are you saying the spark plug color and smoke would be an indication of needing to adjust the carb? Just want to confirm before i swap out air filters, the bike is running pretty good so i dont want to start tweaking carbs.

 

[5twins]

Just wrapping the stock air filter "cages" with fresh foam shouldn't affect the air flow much, if any. You'll still be using the airbox and all the stock "plumbing". Be aware that the special foam filter oil they sell is very thick and tacky. Applying too much might cut the air flow and cause a rich condition. Personally, on my UNI pods, all I use is a 50-50 mix of gas and straight 30 wt. motor oil. It's cheap and easy, and not too thick. I get the cheap Walmart brand 30 wt.

 

[Runnriot]

Just wrapping the stock air filter "cages" with fresh foam shouldn't affect the air flow much, if any. You'll still be using the airbox and all the stock "plumbing". Be aware that the special foam filter oil they sell is very thick and tacky. Applying too much might cut the air flow and cause a rich condition. Personally, on my UNI pods, all I use is a 50-50 mix of gas and straight 30 wt. motor oil. It's cheap and easy, and not too thick. I get the cheap Walmart brand 30 wt.

Gotcha, thank you very much for your response. I really appreciate it.

 

[hovel]

Everything 5twins said is spot on. If you have to adjust anything because of changes you made to the filters, you might want to back up and re-think how you did the filters. I like PJ1 aerosol filter oil, the red stuff, lightly dust it on.

 

[Runnriot]

Just wrapping the stock air filter "cages" with fresh foam shouldn't affect the air flow much, if any. You'll still be using the airbox and all the stock "plumbing". Be aware that the special foam filter oil they sell is very thick and tacky. Applying too much might cut the air flow and cause a rich condition. Personally, on my UNI pods, all I use is a 50-50 mix of gas and straight 30 wt. motor oil. It's cheap and easy, and not too thick. I get the cheap Walmart brand 30 wt.

Would you also use the Pre-Filter before attaching the Uni Filter? Or just go with the Uni filter alone? Right now the motorcycle has a gray/black foam filter with the yellow foam wrapped over it, it seems like the gray one is thicker (im assuming thats a pre-filter) but both are torn up.

Sorry for all the questions. Is the Green Uni filter the recommended one? its thicker than the red Uni, but both seem thicker than the yellow and gray fitlers on the OEM.

https://www.amazon.com/Uni-Filter-6...lter+foam&qid=1594673472&s=automotive&sr=1-10

 

[5twins]

I run pods so I've never had to deal with the factory filters. If I did and was re-wrapping them, I think I'd just use the regular green UNI foam. I wouldn't bother with a second wrap of pre-filter foam. I think that's mostly for pods that are out in the open, and dirt bikes that operate in extremely dusty, dirty environments.

 

[hovel]

No problem with all the questions. I saw the Uni link and I looked at the Mikes XS link for the filter you have. I think the grey/black foam you mentioned is the oval piece at the screen. I think it is just a sealing ring where the filter mounts up and if yours is falling apart you're gonna have to make one. The green Uni foam is 5/8" thick which is a little on the meaty side but worth a try if you have the room. I didn't see any red stuff in bulk. I mentioned the pre-filter material only because it is thinner and may be easier to work with. It is primarily used a a wrap over paper filters on lawn mowers and such and not meant to be a wrap over other foam. Good luck, this will be a fun project.