Has anyone tried using a RU-2970 K&N air filter?

oldgeek

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I have been researching air filters since mikesxs is out of the 57mm ones that fit my carbs.

I came across the dimensions for the RU-2970. I believe it might just fit in the small space directly off of the carbs.
It is a dual inlet, single filter. The inlets are 60mm and the center to center is 106mm.
The center to center i measured on my carbs is about 110mm

I originally wanted to use the stock rubber inlet tubes, and put filters on the ends of them, but on closer inspection the tubes are in poor condition.
 
Well, I took the chance and ordered it. The filter came in, and as you can see it seems to fit fine. I found one on Amazon, for $30.09 including shipping, which I think is a great deal for any K&N filter. The filter will definitely flow more air than just about any other setup, not that it matters in my application. I think it looks pretty good overall. I also got the rotor cover in, and made the gasket for it...progress is slow! (the kitchen repairs are finished!)

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Awesome. I may have to go this route myself. Is there room for a crank case breather under this filter?
 
Awesome, I've been wanted to take another route instead of using 2 pods. A single unit is more what I wanted. Great find, thanks a ton.

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I know this is an old thread, and Im new so sorry. but where is your battery then?
After reading this thread, i bought this airfilter too, and i am very pleased with it

I found a alternative battery and gave it a new location :)
After cutting away a bit of plastic.
2w3rdox.jpg


1zdx3m1.jpg


I cut away 6 mm of the airfilter rubber mountings. This way the lip inside the filters will sit flush with the carburetor intake. :thumbsup:
2hn28sz.jpg
 
After reading this thread, i bought this airfilter too, and i am very pleased with it

I found a alternative battery and gave it a new location :)
After cutting away a bit of plastic.
2w3rdox.jpg


1zdx3m1.jpg


I cut away 6 mm of the airfilter rubber mountings. This way the lip inside the filters will sit flush with the carburetor intake. :thumbsup:
2hn28sz.jpg
Lasse, just out of curiousity, what are the specs on that battery - can't quite read it. I've been looking at doing just that with my battery but was not sure if those type batteries could handle the current draw of headlights + ignition + turnsignal + tail light etc...

Gotta see Denmark one of these days - a few years ago I learned my last name (Davidson) was originally Davidsen (obviously Danish) but Elis Island botched it when my ancestors came to the U.S.

Cheers!

- James
 
I'm running a 1.5 aH 12v AGM battery even smaller than that one and have had no problems, but my bike is kick only. I actually removed the starter relay in the process of wiring in the terminals for the battery. If you want to retain e-start it will be difficult to keep a battery like that healthy.
 
The biggest thing with the smaller batteries is the charge cycle of it. These bikes put out 14.5-7 volts at 5k rpm's. A lot of the little batteries can't take that much and get fried after a while. My 80 has a 1.2ah sealed acid battery that I have been using for 3 years in this bike and 2 years in one of my razz's with about 6k miles total and still holds 12.6v after sitting for weeks. It sat all last winter (in a warm dry basement) without any charge and still had 12.5v come spring. Not bad for a $9 battery. :laugh:
 
I was wondering, since there is a ton of air flow from that type of filter, could you fill in every other "notch" (for lack of a better term) with some type of filler like maybe JB weld or RTV or something? I would think that would cut down quite a bit on airflow. Thoughts?
 
Lasse, just out of curiousity, what are the specs on that battery - can't quite read it. I've been looking at doing just that with my battery but was not sure if those type batteries could handle the current draw of headlights + ignition + turnsignal + tail light etc...

Gotta see Denmark one of these days - a few years ago I learned my last name (Davidson) was originally Davidsen (obviously Danish) but Elis Island botched it when my ancestors came to the U.S.

Cheers!

- James

Here´s the specs on the battery
http://ultracell.net/datasheets/UL2.4-12.pdf

It's 2.4AH capacity and i have no problems with powerloss (kick start only)


A last name ending with "-sen" sounds very danish i agree, that's also the case with my own last name :)
 
I am doing the same kind of thing. But I just cut out the front of the air box, so the battery can stay in the same place. Have two EMGO filters to pick up next time I am on the mainland. I will check to see how much water gets sprayed around the filters. If too much I will change to the double foam type filter. They should not mind touching the frame, located just above the filters. I have 4 1/8 inches from the carbs to the filter box. I will use a longer piece of rubber tubing for the crank vent and locate it elsewhere on the air box. Later I may change to a small filter directly to the crank casing. If there is room. I have main jets in 117.2 122.5 125 127.5 130 and 140.
First test will be with the 125 in each carb. Mine is a DOHC motor. 83 Seca.

Unkle Crusty
 
Hello,
My name is Alex, I know this is an old topic but I hope someone will find this post and help me

I've recently bought an 1981 XS400 Special 4G5 and I've mounted K&N RU-2970 air filter on it.
Did you guys rejet the carbs ?
Can you please tell me what modifications should I make to run well ?
Sorry for my bad english...
Thank you !
 
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