K&N Blockage

[Richmond]

Hey I have rejetted my carbs once based off of past bikes i figured my current set up would do it but it seems lackluster in power so i was planning on rejetting again. I dont want to rejet before i get nicer filters (i currently have cheapoes that i cut to allow some air) because i have a suspicion that the filters have something to do with it. I know K&N's are good because they dont have the little inner flange that blocks passages but just to check again, this type wont have anything blocking it either?

http://www.ebay.com/itm/K-N-Air-Fil...Parts_Accessories&hash=item4d10b89a05&vxp=mtr

its part # K&N RC-2340

 

[Richmond]

Has anybody used them or is currently running them?

 

[Scorpio1963]

I haven't used them personaly but they shouldnt give you any troubles.You can always use the stock air boxes for mounting your filters then you have no problems forsure.

 

[xschris]

When buying pods make sure they are the type that need to be oiled are charged. They filter much better than the grey ones or the mikesxs knock offs. Also are easier to set up. often only needing minor adjustments for the carbs. I run K&N's on my 80 with xs360 carbs and run stock jets.

 

[Richmond]

oh really? hmm. good thing i asked, i doubt ill be ordering any bigger jets after all

 

[xschris]

You still may have to jet but should not be a lot. It also depends on you exhaust and how much back pressure it has.

 

[XSLeo]

The K&N and similar knock offs use a pleated paper element. These type of pods cause air turbulence through the carbs that disrupt the vacuum signal for the slides. Most notable in the off idle to mid range. Leaves a flat spot that is almost impossible to tune out.
The shorter or more the taper increases the effect. The longer straight ones are slightly better.
I as others have found a straight round foam filter, such as Uni Filter doesn't cause this type of air turbulence and perform much better.
Leo

 

[xschris]

This is what I use. There where made for the xs360/400 and use cotton gauze not paper or the crappy mesh stuff most pods use. Used with the xs400's stock H-pipe I have no issues with tuning. My xs360 carb is set to stock setting. Putting a pod directly on a cv carb you will have to tune it a lot more.

 

[XSLeo]

Those are the long straight ones I mentioned. CV carb are very sensitive to air flow turbulence. The long straight K&N's smooth out the air better than the shorter oval tapered ones.
Using the rubber connector as you have smoothes out the air flow before it gets to the carbs. Some bikes don't have that.
Leo

 

[jthiessen]

Don't mean to hijack the thread, but the PO installed the conical filters onto the rubber connector (is that called the H-Pipe?) if that is the only mod should I rejet?

 

[xschris]

When ever making changes to the stock setup re-jetting might need to be done. See how it run at all rpm's and check the plugs and see how they look.

 

[Yamaguy55]

I've used K&N filters for years. They flow just about as much air as no filter at all. They also will pass really fine dirt when clean(ish) and actually work better if dirty. You pull them and reoil from the inside periodically. When you can no longer see the pleats, clean them then. Really.

The air flow will be ok if you keep them oiled. If you run any gauze filter dry, it will cause some turbulence in some cases. But not in every case. If you retain the side covers, that helps a great deal. Hanging out in the wind is probably not the best idea.

I'd guess you'll have to reject at least the main. I doubt the air flow change would affect the pilot circuit, but might change the needle setting. My XS650 needed ( been a while, not really sure) at least one size up on the main, maybe two. I think the needle needed the clip moved down one groove as well. I had '77 BS38s on it, they were adjustable. The pilot circuit should be able to be corrected with the mixture screw.