hi guys and girls,

i am making a bobber of my LS650 '86

I already deleted my standard airbox and made some changes so I can't use this anymore.

so I am looking for some opinions in what K&N airfilter I should buy.( i am nog relocating the battery so I don't have a lot of space left to bolt it on the back of the carbu )

Can anybody in the same setup give me a type of K&N filter they used ? ( example RC- xxxx )


Also what other modifications did you do to the carburator and can you send me links of these materials used for these modifications?


Thanks in advance  !!!

 I agree with Dave here.  K&N under testing has very average performance, and nowhere near as good as the mods presented in the tech section on this forum.

https://photos.app.goo.gl/Tw7pmUgEfpXzEkXq9

Sorry about the Budweiser theme in my photos. I'm pretty much broke and my neighbor supplies beer for free, so it's currently pretty prevelent in my projects lately.

I'm with you SCS40, love K&N filters.  Been using them close to 50 years.  Always have worked great for me.  When I flow test them they always kill the competition.  I've never had any sort of failure that could be attributed to the air filter, and I certainly don't wear out rings or valves.

I've been doing a lot of testing over the last month and it centers around K&N filters.  I've found that the K&N Flat Panel filter works best in the stock airbox on the stock carb.  Try that airbox setup with a VM or PWK and it doesn't work so good.  The aftermarket carbs need more air than the 25 square-inch flat panel can provide.  Conversely, the stock carb doesn't much like a larger filter.  Install a K&N RD-0710 (55 square-inches) and the stock carb does not run as good as it does with the flat panel filter.   It's a mystery that I'm still trying to figure out.  I think it's related to the CV feature, pressures above & below the diaphragm, etc. Bottom line, the CV carb likes the smaller filter element.

If you run a hi-flow filter on the stock carb, the needle and needle jet combination just can't deliver enough fuel.  With the stock needle, it runs grossly lean with that big filter (even with a #205 main jet).  If you modify the needle, you can get it to run good, but it still won't match the performance of the stock carb with the flat panel K&N.

Donkey Wonkey, a 2" ABS street elbow works good to adapt a K&N RD-710.  It will practically be a bolt-on installation, but if you run the stock carb you will have to modify your slide needle and increase the main jet a whole bunch.  A lot of that will depend on what exhaust your are running.  This is the setup, simple & cheap.

Since you have removed your airbox, the filter and elbow will slip right into place.  However, I suggest a K&N RD-0700 which is an inch shorter.  That will cut down some of the surface area.  The RD-0710 and RD-0700 both fit perfectly onto the 2" ABS elbow.  You want a "Street Elbow".  That's an elbow with a 2" male connection on one end, and a 2" female connection on the other end.

You can also run a UniFilter on that elbow.  That won't flow as well, but I bet it would be easier to tune.  Lancer sells a UNI # UP-4245AST that fits perfect.  This should give you an idea what the flow-path looks like using the 2" ABS street elbow.  The picture shows the setup on a VM carb, but the setup is the same for the stock carb.  The stock air boot fits fine.