K&N air filters

[Gpaws1968]

Hi all,

I want to install K&N filters on my 1981 XS650 with standard carbs. Does anyone give me a ballpark for the carburation, Jets, and needles ...........

 

[Raymond]

I'm guessing the ballpark around here for K&Ns would be don't fit them. Depending which carbs you have, the K&N blocks off one or more vents in the carb. Plus they are said to be hard to tune anyway. So my question is, why K&Ns - are you set on them or have you considered other filters?

 

[Its been a long time]

Indeed, it seems the favoured aftermarket air filter are the foam ones rather than the pleated ones.

 

[dave_a]

The K&N's I tried to put in my Tiger 1050 would not sit flat and seal out dirt properly in the OE airbox like the OE filter did. K&N chose to do nothing.
My suggestion is to give someone else your money.
I have "two stage" UNI'S on my 650/ no airbox. They seem to work fine. Not too loud either.

 

[jetmechmarty]

Hi all,

I want to install K&N filters on my 1981 XS650 with standard carbs. Does anyone give me a ballpark for the carburation, Jets, and needles ...........

I’ve been running them for many years. Stock jetting. I just revisited those carburetors recently. Still stock jets.
My Factory Service Manual shows two main jet sizes as stock. The larger is what I run. I think it’s 135.
My exhaust is also factory. I’m not running lean I assure you.

 

[650Skull]

Are the K&N's the ones that go in the factory airbox or replace the factory airbox??

 

[Kevin Werner]

Pics?

 

[5twins]

Yes, the K&N pods are the ones that give issues. The airbox replacements are fine as far as I know (but expensive). If you are going with the airbox replacements, jetting changes will have to "wait and see". But, being that the BS34s were borderline too lean right out of the factory, and any little change seems to throw them off, I'd say some minor re-jetting will be called for. In fact, a totally stock BS34 equipped bike runs better with one size up on the mains, so I'd do that anyway. And you can also richen the idle circuit slightly by decreasing the air jet a size or two. This won't have as big of an effect as changing the pilot jet size, but it will make the circuit slightly richer. This is a nice feature on the BS34s. With it you can fine tune the plug color and the height of the smoke ring on the porcelain, and help alleviate popping on decel.

 

[jetmechmarty]

Are the K&N's the ones that go in the factory airbox or replace the factory airbox??

My response applies to those expensive filters that fit in the airbox.

FWIW, seat of the pants and jetting, the original filter frames covered in Uni foam performance is identical to the K&N filters in my experience.